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United States Patent Application20030061506
Kind CodeA1
Cooper, Geoffrey ; et al.March 27, 2003
System and method for security policy
Abstract
A network security policy monitoring system and method for performing network and security assessments based on system-wide policy. Real network traffic is analyzed to identify abnormal traffic patterns, system vulnerabilities, and incorrect configuration of computer systems on a network, by listening on a network, logging events, and taking action.
Inventors:Cooper; Geoffrey (Palo Alto, CA), Shaw; Bob  (Los Altos, CA), Valente; Luis  (Palo Alto, CA), Sherlock; Kieran G.  (Palo Alto, CA)
Correspondence Name and Address:3475 EDISON WAY SUITE L
GLENN PATENT GROUP
MENLO PARK
CA
94025
US
Series Code:881147
Filed:June 14, 2001
U.S. Current Class:713/201
U.S. Class at Publication:713/201
Intern'l Class:G06F 011/30
Claims

1. A system for analyzing network traffic to use in performing network and security assessments by listening on a subject network, interpreting events, and taking action, comprising: a policy specification file; a network monitor processor for processing network packet data collected from said subject network; and a policy monitoring component for receiving and processing said policy specification file, and receiving and processing said processed network packet data to assign dispositions to network events contained in said network packet data.

2. The system of claim 1, said policy monitoring component further comprising: a parser for parsing said policy specification file; a policy engine for synthesizing said parsed policy specification file and said processed network packet data, and for performing said assign dispositions and level of severity to said network events contained in said network packet data; and a logger for logging and storing into an events database said synthesized information by said policy engine according to a logging policy file.

3. The system of claim 2, further comprising: a query mechanism for mining said stored data in said events database.

4. The system of claim 2, further comprising: an alarm script component for generating alarms based on said level of severity of said network events.

5. The system of claim 2, further comprising means for said policy engine: interpreting each protocol event; and consulting said policy specification file as each protocol event is interpreted to ensure that an earliest determination of said disposition is reached.

6. The system of claim 1, wherein said collected network packet data is captured in a file or is streams-based.

7. The system of claim 1, further comprising: a secure Web server comprising a Web server component and a report database for displaying reports online, said reports generated by said events database using a report script.

8. The system of claim 1, further comprising: a parser for generating an English description policy representation from said policy specification file.

9. The system of claim 1, wherein said network monitor processor is used in standalone mode.

10. The system of claim 1, wherein said network monitor processor and said policy monitoring component run on a same machine.

11. The system of claim 1, further comprising: a policy generator for generating said policy specification file.

12. The system of claim 1, wherein said received network packet data is encoded.

13. A method for analyzing network traffic to use in performing network and security assessments by listening on a subject network, interpreting events, and taking action, said method comprising: providing a policy specification file; providing a network monitor processor for processing network packet data collected from said subject network; and providing a policy monitoring component for receiving and processing said policy specification file, and receiving and processing said processed network packet data to assign dispositions to network events contained in said network packet data.

14. The method of claim 13, said provided policy monitoring component further comprising: providing a parser for parsing said policy specification file; providing a policy engine for synthesizing said parsed policy specification file and said processed network packet data, and for performing said assign dispositions and level of severity to said network events contained in said network packet data; and providing a logger for logging and storing into an events database said synthesized information by said policy engine according to a logging policy file.

15. The method of claim 14, further comprising: providing a query mechanism for mining said stored data in said events database.

16. The method of claim 14, further comprising: providing an alarm script component for generating alarms based on said level of severity of said network events.

17. The method of claim 14, further comprising said policy engine: interpreting each protocol event; and consulting said policy specification file as each protocol event is interpreted to ensure that an earliest determination of said disposition is reached.

18. The method of claim 13, wherein said collected network packet data is captured in a file or is streams-based.

19. The method of claim 13, further comprising: providing a secure Web server comprising a Web server component and a report database for displaying reports online, said reports generated by said events database using a report script.

20. The method of claim 13, further comprising: providing a parser for generating an English description policy representation from said policy specification file.

21. The method of claim 13, wherein said network monitor processor is used in standalone mode.

22. The method of claim 13, wherein said network monitor processor and said policy monitoring component run on a same machine.

23. The method of claim 13, further comprising: providing a policy generator for generating said policy specification file.

24. The method of claim 13, wherein said received network packet data is encoded.

25. A method for interatively developing network security policy for a network, comprising: creating an initial network security policy file; ensuring said initial network security policy file is uploaded to a machine on said network; running a network monitor on said network machine to collect said network traffic; said network monitor outputting said collected network traffic in an output file, and passing said output file to a policy monitor; said policy monitor analyzing said collected network traffic; storing said analyzed network traffic in a database; examining said analyzed network traffic in said database by querying said database using a query tool; and modifying said initial network security policy file as needed until a comprehensive and desired policy file is attained.

26. The method of claim 25, wherein said network machine is remote, and further comprising uploading said modified network security policy file to said remote network machine as needed.

27. The method of claim 25, further comprising: monitoring network traffic by using said attained comprehensive and desired policy file.

28. The method of claim 27, wherein monitoring network traffic is on a continuous basis.

29. The method of claim 25, further comprising: generating reports from said database, and using said generated reports as input for further policy refinement and/or using said generated reports for continuously monitoring network traffic.

30. The method of claim 29, further comprising: encrypting said reports, and sending said encrypted reports to a remote secure Web server.

31. The method of claim 30, further comprising: accessing said reports on said remote server in a user-friendly manner.

32. The method of claim 25, wherein creating an initial network security policy file, and modifying said network security policy file as needed use a policy generator tool.

33. A system for interatively developing network security policy for a network, said system comprising: means for creating an initial network security policy file; means for ensuring said initial network security policy file is uploaded to a machine on said network; means for running a network monitor on said machine to collect said network traffic; means for said network monitor outputting said collected network traffic in an output file, and passing said output file to a policy monitor; means for said policy monitor analyzing said collected network traffic; means for storing said analyzed network traffic in a database; means for examining said analyzed network traffic in said database by querying said database using a query tool; and means for modifying said initial network security policy file as needed until a comprehensive and desired policy file is attained.

34. The system of claim 33, wherein said network machine is remote, and further comprising means for uploading said modified network security policy file to said remote network machine as needed.

35. The system of claim 33, further comprising: means for monitoring network traffic by using said attained comprehensive and desired policy file.

36. The system of claim 35, wherein monitoring network traffic is on a continuous basis.

37. The system of claim 33, further comprising: means for generating reports from said database, and using said generated reports as input for further policy refinement and/or using said generated reports for continuously monitoring network traffic.

38. The system of claim 37, further comprising: means for encrypting said reports, and sending said encrypted reports to a remote secure Web server.

39. The system of claim 38, further comprising: means for accessing said reports on said remote server in a user-friendly manner.

40. The system of claim 33, wherein means for creating an initial network security policy file, and modifying said network security policy file as needed uses a policy generator tool.
Description


CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation in Part to U.S. Ser. No. 09/826,602 filed Apr. 5, 2001 (Attorney Docket No. SECU0001).

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The invention relates to security and network services. More particularly, the invention relates to a system and methods for implementing a system-wide security policy for an entire computer network, and for providing monitoring and enforcing of computer network security.

[0004] 2. Description of the Prior Art

[0005] Networked information systems are an essential part of many organizations. Critical systems, services, and information resources all require protection that depends on effective orchestration of a variety of factors: network architecture, security products, site security, administrative procedures, end user responsibility, and more. A network security policy is an explicit plan of how to accomplish this multi-faceted protection, what objectives the plans should meet, and what assets are being protected.

[0006] To manage a network, an end user needs to know and understand what is happening on the network. Most security holes come from unexpected, misconfigured, or unauthorized services, for example, from a high-port telnet, a new service added in, a rogue server, and/or a misconfigured workstation. The end user doesn't know what is the unauthorized network traffic.

[0007] Security administrators need tools to help them formulate site security policy and to translate the policy into monitoring and enforcement mechanisms. They need to be sure that the computer enforced policy--often cobbled together from a plethora of disjoint access control mechanisms--matches their enterprise policy, all too often specified in a loose natural language or a set of unwritten principles. This leads to confusion as to why access is being granted or denied to particular resources and may lead to unintentional breaches of security.

[0008] In addition to monitoring network system traffic, it is important for network analysts to assess their network's configuration. A discussion on current techniques for network assessment follows below.

[0009] A conventional network assessment visit determines the customer network using the following information:

[0010] 1) Network security scanning technology, e.g. port or vulnerability scans;

[0011] 2) Customer interviews;

[0012] 3) Inspection of customer log files, perhaps using machine aggregation and filtering; and

[0013] 4) Occasionally, inspection of customer log files and network traffic.

[0014] As a matter of practicality, the information is typically derived from the first three of these items. Customer log files and network traffic is of a volume so great that it is impractical to examine it in a short assessment visit.

[0015] The weaknesses such conventional methods are as follows:

[0016] Vulnerability Scans

[0017] Network vulnerability scanners only detect certain types of known vulnerabilities. Such vulnerabilities are generally not detected directly, but are inferred based on host responses to a series of network packets sent to hosts by the scanner. This process does not directly ensure that data traffic on the subject network matches expectations, either explicit or implicit.

[0018] Network vulnerability scanners cannot see a host if it does not respond to packets. A host that is only a source of network packets, such as, for example, a rogue router, is not visible to a scanner. Hosts which are turned off or otherwise temporarily disconnected, such as, for example, workstations and laptops, are often missed by vulnerability scanners. This problem is compounded by the fact that scans are often scheduled for non-work hours in order to alleviate customer fears that the scans will somehow impact production systems and organizational mission.

[0019] Network scanners typically return a large volume of vulnerability information, based on all possible configured elements in a network. The scanner tools cannot currently interpret those vulnerabilities in light of business requirements which the subject systems are intended to support, or even for the specific network architecture of which those systems are a part. The scan results must be reviewed manually by a security analyst, who applies his or her knowledge of the business requirements and network architecture to an interpretation of those results. Such manual process is error-prone because the volume is so great that problems may be overlooked.

[0020] Another problem is that the scan derives only vulnerabilities, not network usage patterns. Therefore, the scan cannot detect security problems that are attributable to human behavior, but only those scans that result from misconfigured systems and/or systems which have documented design problems.

[0021] Network scanners cannot diagnose incorrect client usage of software. For example, network scanners cannot detect whether web servers are being used with invalid ciphersuites, whether 40-bit browsers are in use, and whether a given telnet port is accessed only by a management station.

[0022] Network scanners must be targeted to particular subnets. If a customer has forgotten to mention a subnet, the scanner will not notice it.

[0023] Customer Interviews Customers may not provide the network analyst complete or accurate information, either because the customer forgot details, because the information is not known to the customer, or because the customer does not understand the importance of giving the information to the analyst.

[0024] Customer interviews at best can provide descriptions of overt usage of subject systems, and generally not covert usage. Often, formal policies of the organization are not even documented, much less promulgated, audited and enforced.

[0025] Hidden agendas, office politics, and other factors also can affect the success of the interview process.

[0026] Host Inspection

[0027] Inspecting host configuration files is a time consuming, manual process that is subject to human error. In the assessment of any large network, it is impractical to include an inspection of the configurations for more than a few critical systems.

[0028] Once again, inspection of host configurations does not reveal completely intended usage of the subject systems. The configurations must be analyzed within the context of the business requirements and overall security environment of the organization. This manual process is very human dependent and prone to error.

[0029] Log File Inspection

[0030] Log file inspection can provide great insight into the workings of network components. Machine-based aggregation and filtering systems can speed this process. However, logs provide only a components' own view of its status. If a component is misconfigured, the log data from the component cannot be trusted. Log data may also be subject to modification by an attacker who has penetrated the machine and is seeking to mask his presence.

[0031] In addition, since log aggregation systems work in cooperation with the components that generate the information, they require configuration changes to every component that they examine. Also, they are unable to detect when a component is added to the system.

[0032] Such techniques of performing network assessments generally are limited in their ability to determine actual security threats to information systems. Generally, they represent the state of the art and are indicative of best practices within the security community today.

[0033] A way to reduce or eliminate the confusion described above is by providing a user-friendly and, yet, rigorous way of specifying security policy, as well as providing tools for monitoring and enforcing the security policy.

[0034] It would be advantageous for a network policy to provide the definition of normal traffic on the network.

[0035] It would be advantageous to provide a monitoring mechanism that lets an end user determine and understand traffic and/or activity on a network.

[0036] It would be advantageous to provide methods and system that, when given known network characteristics, thereby spots intruder access, and track changes to a network.

[0037] It would be advantageous to provide a policy generator tool that assists an end user in generating security policy for a network.

[0038] It would be advantageous to provide a tool that automatically converts a network security policy into English language representation.

[0039] It would be advantageous to provide a tool that allows an end user to query network traffic data.

[0040] It would be advantageous to provide a technique for transmitting an event description of network traffic from a source file or data stream to a target destination, such as a network policy engine.

SUMMARY OF THE INVENTION

[0041] The invention is a network security policy monitoring system and method that comprises supportive features, algorithms, and tools. It is ideally suited for network and security assessments or long-term monitoring where real network traffic is analyzed to identify abnormal traffic patterns, system vulnerabilities, and incorrect configuration of computer systems on the network. The invention listens on a network, logs events, and takes action, all in accordance with a rule based system-wide policy. The invention is able to incorporate external sources of event information, such as are generated in log files of other network components. The invention gets protocol information, which can make it more meaningful to a network administrator.

[0042] The invention sends data upstream to an event log and interprets the data. It listens to secure protocols and can identify encryption quality of service parameters. It extracts basic security parameters, such as, for example, network events, and passes them to a policy manager component.

[0043] The policy manager component implements system-wide policies, based on monitored system or enterprise traffic. The policy manager component provides a trust manager that takes as its input a security policy defined as a set of policy rules and a set of credentials, and that is capable of processing requests for trust decisions, i.e. evaluating compliance with the policy. Unlike other trust management systems, the invention is designed to be a passive monitor of network traffic. As such, it need not be installed on target hosts or integrated into existing applications.

[0044] Two key aspects of the policy manager component are provided. One aspect is a unified view of the interaction between two principals across a stack of protocol areas, each area covered by discrete policy rules. The final trust decision applied is based on policy rules that better fit the entire interaction. The second aspect comprises the policy manager's policy definition language that supports the monitoring and auditing of a network's activity in addition to traditional access/denial authorization decisions.

[0045] The policy definition language is the subject of U.S. patent application Ser. No. 09/479,781, filed Jan. 07, 2000, entitled, "A Declarative Language for Specifying A Security". The policy definition language is discussed herein to the extent necessary to explain such language to those skilled in the art in connection with the invention disclosed herein. The declarative language system comprises a language as a tool for expressing network security policy in a formalized way. It allows the specification of security policy across a wide variety of networking layers and protocols. Using the language, a security administrator assigns a disposition to each and every network event that can occur in a data communications network. The event's disposition determines whether the event is allowed, i.e. conforms to the specified policy or disallowed and what action, if any, should be taken by a system monitor in response to that event. Possible actions include, for example, logging the information into a database, notifying a human operator, and disrupting the offending network traffic. Further details of the policy definition language can be found in the patent application cited herein above.

[0046] Unlike Intrusion Detection Systems (IDS) systems, which look for the signatures of known attacks, the invention herein is focused on defining allowed traffic patterns and how to handle events that deviate from those patterns.

[0047] The invention comprises, but is not limited to, six major features and tools. The first feature discussed is auto-conversion of policy language, whereby policy language is converted to an English language representation. Next, an algorithm for efficient rule evaluation is provided. Then, a credential/assertion optimization technique is provided. A policy generator tool is provided. An embodiment in which the invention is used as an assessment tool is provided. Finally, a technique for secure sensitive event extraction from protocol monitoring is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG. 1a is a schematic diagram of components of the system according to the invention;

[0049] FIG. 1b is a schematic diagram of components of the system according to the invention;

[0050] FIG. 2 is a high level workflow flow diagram according to the invention;

[0051] FIG. 3 is an example of a policy wizard dialog box according to the invention;

[0052] FIG. 4a is an example of a policy wizard dialog box according to the invention;

[0053] FIG. 4b is an example of a policy wizard dialog box according to the invention;

[0054] FIG. 5 is an example of a policy monitor dialog box according to the invention;

[0055] FIG. 6 is an example of a query tool dialog box according to the invention;

[0056] FIG. 7 is an example of a query tool dialog box according to the invention;

[0057] FIG. 8 is an example of a query tool dialog box according to the invention;

[0058] FIG. 9 is an example of a query tool dialog box according to the invention;

[0059] FIG. 10a is an example of a policy wizard dialog box according to the invention;

[0060] FIG. 10b is an example of a policy wizard dialog box according to the invention;

[0061] FIG. 10c is an example of a policy wizard dialog box according to the invention;

[0062] FIG. 11 shows a high-level view of an example network according to the invention;

[0063] FIG. 12 shows an algorithm according to the invention;

[0064] FIG. 13 shows a flow diagram according to the invention;

[0065] FIG. 14 shows an algorithm according to the invention;

[0066] FIG. 15 shows a high level schematic diagram according to the invention;

[0067] FIG. 16 shows a schematic diagram of process flow according to the invention;

[0068] FIG. 17 is a block schematic diagram according to the invention;

[0069] FIG. 18 is a high level flow diagram of the preferred output section according to the invention;

[0070] FIG. 19 shows a schematic diagram according to the invention;

[0071] FIG. 20 is an example of a dashboard according to the invention;

[0072] FIG. 21 shows an example of a tear off console according to the invention;

[0073] FIG. 22 shows an example of an events summary view according to the invention;

[0074] FIG. 23 shows an example of a conformance event details page according to the invention;

[0075] FIG. 24 shows an example of a protocol event details page according to the invention;

[0076] FIG. 25 shows an example of an events summary page containing a pop up description according to the invention;

[0077] FIG. 26 shows an example of an events summary page containing a pop up description according to the invention;

[0078] FIG. 27 shows an example of a conformance event details page containing a pop up description according to the invention;

[0079] FIG. 28 shows an example of an alert details page according to the invention;

[0080] FIG. 29 shows an example of a violators chart and table page according to the invention;

[0081] FIG. 30 shows an example of a targets chart and table page according to the invention;

[0082] FIG. 31 shows an example of an advanced search dialog box according to the invention; and

[0083] FIG. 32 shows an example of a link to the advanced search dialog box according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0084] The invention is a security policy monitoring system and its supportive features, algorithms, and tools. It is ideally suited for network and security assessments where real network traffic is analyzed in order to identify abnormal traffic patterns, system vulnerabilities and incorrect configuration of computer systems on the network. The system listens on a network, logs events, and takes action, all in accordance with a rule based system-wide policy. The system is able to incorporate external sources of event information, such as are generated in log files of other network components. The system gets protocol information, which can make it more meaningful to a network administrator. The invention sends data upstream to an event log and interprets the data. The system listens to secure protocols and can decrypt a session if a key escrow facility is available. The system extracts basic security parameters, such as, for example, network events, and passes them to a policy manager component.

[0085] An important part of understanding the invention is understanding network security terminology for policy monitoring. See Table A below.

1TABLE A Terminology Network Event: One complete transaction on the network, such as a FTP connection or a HTTPS transaction. Each network event has several component protocol events. Protocol Event: A transaction at one protocol level. For example, a net- work event that represents an FTP connection has protocol events repre- senting an IP association, a TCP connection, an FTP control connection, and several FTP control commands. Initiator, Target: The endpoints of a network event or protocol event. Credential: An identification of the initiator or target of a protocol event at a particular protocol level. For lower-level protocols, credentials are, for example, IP addresses or UDP port numbers. For higher level protocols, credentials are, for example, user names, file names, or public key certificates. Association: A placeholder for a transaction run over a datagram-based protocol such as IP, ICMP or UDP. The invention herein constructs an association to collect a conversation between two hosts, or processes in the case of UDP. It is noted that when the invention misses any data packets between the two communicating computers, it might not be able to determine the initiator and the target of the association. Associative array: A list of value pairs where each associative array entry is indexed by the first element of its value pair, which is called the key. Keys are stored in a hash table to make lookups efficient irrespective of the size of the associative array. Rule: A policy rule governs a specific interaction, or set of interactions, between two communicating entities. The invention evaluates policy rules against protocol events to determine if the latter conform to the active security policy. Disposition: The policy definition of what action or state change needs to take place in response to a network event. Policy Domain: A top level segmentation of a network, roughly akin to a cloud-like object in a network diagram, which hides internal detail. Within the policy domain communities of hosts provide or access services. One community of hosts defines the limits of the domain. Monitoring Point: A point within a policy domain where it will be possible to plug a machine into the network in order to collect packet data. Communities of Hosts: A mechanism for grouping hosts that have a similar function, e.g. all web servers or all NT workstations. Perimeter Element: A hardware device that allows access to and from communities of hosts outside a policy domain. Examples of perimeter elements are firewalls and routers. Policy Language: A policy language is used to create a formal specifica- tion of a network security policy. The preferred embodiment of the invention incorporates the policy definition language of U.S. patent application Ser. No. 09/479,781, filed 01/07/00, entitled, "A Declarative Language for Specifying A Security Policy." It defines first class objects such as rules, credentials and dispositions. It is based on s-expressions, which are LISP-like parenthesized expressions. Rogue server: A machine introduced to a network that is not authorized to be on that network. Rogue router: An unauthorized router that is added to a network, providing an alternate path into the network. Typically occurs through misconfigur- ation of switches or dialup connections. Real-time monitoring: Reading packet data off a network and processing it to events in a stream, so that an event appearing in the network causes a corresponding event in the stream a short time later. DLL: Any kind of a dynamically linked library

I. System Overview

[0086] The preferred embodiment of the invention functions by translating traffic on the network into protocol events that are themselves combined into network events. As protocol events are detected, they are compared against a policy. The policy specifies a disposition of the network event, as defined by the observed series of protocol events. Information about the protocol events, the network event and its disposition is stored in a database. This database of network traffic information can be mined for policy violations.

[0087] This preferred embodiment of the invention is described with reference to FIG. 1a. FIG. 1a is a schematic diagram of components of the system according to the invention. The system comprises a policy monitoring component 100 that takes as input a policy file 105 that has been generated using a policy generator wizard 110 or other means, and a file containing network packet dump data 115 that has been collected off of an observed network 125 by a packet capture 126, or that has been processed by a protocol monitor processor 127. The system can also process packet event data from the observed network 125 in a continuous real-time mode, without first storing packet data to a file.

[0088] The policy monitoring component 100 comprises a policy manager component 106 that itself comprises a parser 101 for parsing the policy file 105, a policy engine for 102 for assigning policy dispositions to network events, and a logger 103 for determining how to log the information processed by the policy engine 102, according to an input logging policy 130. It also comprises a database 104 for storing synthesized information of the packet dump's 115 conformance to the specified policy 105 performed by the policy engine 102, where it can be mined with a query tool 135. It also comprises a report script component 160 for querying the database 104 and creating reports 161, and an alarm script component 155, for generating alarms based on the severity of the disposition assigned to network events.

[0089] An equally preferred embodiment of the invention also comprises a parser tool 150 that takes the policy specification file 105 as input and automatically generates an English description of the policy 151 for the end user. The parser tool 150 is optional.

[0090] An equally preferred embodiment of the invention also provides a secure Web server feature 162 for the end user to review reports from the end user's host computer 163. The secure Web server feature 162 comprises the Web server 164 and a report database 165 that hosts the reports 161
generated using the report script 160. The Web server feature 162 is optional. A

[0091] n equally preferred embodiment of the invention provides secure management connections (141, 142) and a secure management host 140 for managing the policy monitoring component 100 and the combination of the network monitoring components 128, respectively.

[0092] FIG. 1b shows a simpler embodiment of the invention, wherein the parser tool 150 and the secure Web server feature 162 are omitted.

[0093] The default action of the policy engine 102 is that it denies all traffic. The policy 105 opens holes in this denial to allow permitted traffic to flow. Although the policy engine 102 assigns a single disposition to an entire network event, the protocol events are significant. As network data 115 arrives, the policy engine 102
interprets protocols and generates updates of protocol event information. The policy 105 is consulted as each new piece of information arrives, so that the earliest determination of disposition is reached. For example, if the policy 105 states that a given IP address may not communicate with another IP address, the policy 105 can generate a disposition immediately upon receiving the first packet 115 of the network event.

[0094] To aid policies in early determination of disposition, the policy language divides dispositions into immediate and final. An immediate disposition fires immediately, i.e. its value becomes associated with the network event right away. A final disposition sets a bookmark to itself as the latest and best disposition. When all protocol events are processed without an immediate disposition, the last bookmark set is the disposition that is applied to that network event. Immediate dispositions are designed to generate early results and to allow policy writers to issue a definitive disposition for the network event based on the information received up to that point. Final dispositions allow for the possibility that a better disposition might be determined later on, in other words, allow the policy engine 102 to make a more informed decision based on additional protocol events that might be received as the network event progresses.

[0095] Overview of the Components

[0096] An overview of main components of the preferred embodiment of the invention is discussed below with references to FIG. 1.

[0097] Policy Generator

[0098] The preferred embodiment of the policy generator component 110, also referred to as policy wizard, is a program that makes an end user readily able to generate a first-pass policy for a new site. Policy information is input into a set of dialog boxes and a policy is generated. The wizard enables the end user to generate policy based on what can be considered gross characteristics of a network at the IP level, such as, for example, policy domains, communities of hosts, servers, subnets and firewalls, as well as at the UDP/TCP service level (for example, communities of hosts that can access certain services on server hosts).

[0099] Once a policy has been generated with the wizard, it is output in the policy specification language 105 so that it may be directly processed by the policy monitor component 100. The policy wizard 110 is also able to save files at the wizard level, i.e. such that the policy may be refined in the wizard and re-generated.

[0100] Policy Monitor

[0101] The policy monitoring component 100 comprises a suitable user interface such as an MFC-based front end or a command line interface, and the policy manager 106. The policy manager 106 performs the actual examination of a sequence of event updates stored in a file or transmitted in a continuous stream 115 in the context of a policy specification 105 and signals the adherence to the policy via records written to the database 104.

[0102] Network Monitor

[0103] The network monitor component 127 provides the following capabilities:

[0104] Streams-based interpretation of packet dump data 126 in, for example, DMP format; and

[0105] Packet- and connection-based textual logging of protocol information. Logging is selectable by protocol and may be enabled only for one or more connections. In another embodiment of the invention, the network monitor 127 can perform serialization of event data. That is, the network monitor 106 can process a packet capture file 126 into a series of event updates that contain only the salient security details for processing by the policy monitor 100. The resulting file is significantly smaller than the original, for example, approximately {fraction (1/20)}.sup.th to {fraction (1/100)}.sup.th the size of the original. It is also possible for sensitive data, such as passwords and documents, to be removed from the file. However, it should be appreciated that the original packet capture file is needed to perform full analysis.

[0106] In another embodiment of the invention, the network monitor 127 can read packet data directly from observed network 125, generating a continuous stream of event updates for the policy monitor 100. This stream operates in real-time so that the policy monitor 100 processes events shortly after they happen on observed network 125.

[0107] It should be noted that the network monitor 127 can be used as a standalone tool, but typically is invoked from within the policy monitor component 100 and the query tool 135 in normal operation of the invention.

[0108] It should also be noted that the network monitor and the policy monitor may run on the same machine.

[0109] For a more detailed discussion on the internals of the network monitor, refer to section, VI. Network Monitor Internals Descriptions, herein below.

[0110] Query Tool

[0111] The query tool 135 allows the end user to view the data that has been stored in the database 104 by the policy manager 106.

[0112] Policy Compiler

[0113] The policy compiler performs syntactic and semantic checking of a policy specification. Upon successful compilation the compiler as controlled by runtime arguments, may:

[0114] generate a DLL containing a compilation of credential and condition verification code; and

[0115] generate a pseudo-english report that summarizes the policy.

[0116] It should be appreciated that it is not necessary to run the compiler because the policy monitor component will automatically compile and install a policy from the policy specification file.

[0117] Platform

[0118] The policy generator 110 runs on a Windows NT or Unix machine while the policy monitor 100 and the network monitor 127 run on Linux machine(s). It should be appreciated that these components can run equally well on other suitable operating systems. In addition to policy and network monitoring software, the following software components are also installed on the appropriate machines:

[0119] Microsoft Visual C++ 6.0;

[0120] Sybase ASE 11.9.2; and

[0121] NT NDIS packet drivers and Windump 2.0.

[0122] It should be appreciated that these components can run equally well on other compilers, databases, and packet monitoring systems.

[0123] Policy Files

[0124] There are two file types that are used within the invention's environment, and are described below in Table B.

2TABLE B File Type Suffix Description Policy wizard File .spw Intermediate file used by the policy wizard to store policy information between invocations. Policy monitor File .spm Output file generated by the policy wizard and used as the policy input into the policy monitor. Contains a description of the policy in the policy language.

[0125] The preferred embodiment of the invention incorporates a high level workflow method for developing policy, as follows:

[0126] 1) Creating an initial policy using the policy generator tool;

[0127] 2) Uploading the policy file to a remote machine;

[0128] 3) During the initial policy development phase, running the network monitor to collect traffic, and the policy monitor to analyze traffic separately, as follows:

[0129] a) Running the network monitor and specifying an output file of the collected traffic, and possibly specifying via parameter a limit to the number of packets captured, e.g. 50,000;

[0130] b) Running the policy monitor to analyze traffic collected by specifying the file containing the collected traffic;

[0131] 4) Examining the output of the policy monitor run by querying the database using the query tool;

[0132] 5) Modifying the policy as needed using the policy generator tool; and

[0133] 6) Repeating steps 2 through 5 until a comprehensive desired policy is defined. At this point the end user may start monitoring network traffic on a continuous basis, and using generated reports as input for further policy refinement.

[0134] High Level Workflow Example

[0135] The high level workflow described above can be illustrated further by understanding an example, as follows. System components of the invention are referenced using FIG. 1. Screen interactions are described with reference to the preferred embodiment of the invention. Other screen displays with similar function might equally well embody the invention.

[0136] Referring to FIG. 2, an initial policy is generated (201). Often the initial policy is created from corporate network policy, in whatever form that may take, and a network topology diagram. For the sake of this example, it is assumed that the policy wizard 110 was used to generate an initial, simple policy 105.

[0137] Next, compliance of current network traffic to this initial policy is monitored (202). Such monitoring is achieved by collecting packet information off the network and running such data 115 against the initial policy 105 using the policy monitor 100.

[0138] Then the query tool 135 is used to data-mine output network event data from the database 104, using the mined data to check for traffic that is not consistent with the policy 105, and reporting the results (203).

[0139] Once anomalies have been found, the next step is to work out where the problem lies. The problem could be network equipment is misconfigured and needs to be corrected (203); otherwise acceptable behavior is not covered currently by the policy specification file the file needs to be corrected (204); or, otherwise acceptable behavior is not covered currently by the corporate policy and the corporate policy needs to be corrected (205). In the case of this example, it is assumed that the policy specification 105 is incomplete and an end user needs to add a new rule to permit the observed traffic pattern.

[0140] Generate a Policy Specification File From a Wizard Policy

[0141] The end user starts the policy generator tool, or wizard 110, by double clicking on a policy wizard shortcut on the end user's desktop. In the preferred embodiment, a window such as depicted in FIG. 3 opens.

[0142] In this example, the end user has opened a file, c:.backslash.spm.backslash.quickstart.backslash.null.spw, through the File->Open menu item 301. This file contains a very simple policy that defines a single policy domain defined by a 10.0.0.0/8 subnet mask. Rules within this policy deny essentially all traffic.

[0143] The end user chooses to compile the policy, whereby the dialog box in FIG. 4 opens. The end user presses the "Process Policy" button 401 and a file named null.spm in the output file exntry field 402 is generated and saved.

[0144] FIG. 4b shows the dialog box in FIG. 4a with printed results from the compile process in a text window 403.

[0145] File Running Policy Monitor Over Canned Data

[0146] The end user starts the policy monitor 100 by double clicking on a policy monitor shortcut on the desktop. In the preferred embodiment, a window such as depicted in FIG. 5 opens.

[0147] The end user ensures that the "Input Dump File" entry field 501
points to a data dump file, here qs.dmp, and that the "Policy" entry field 502 points to the null.spm (monitor) file that the end user generated above. The "Monitoring Point" entry field 503 is derived from a policy domain name "Intranet" that is present in the null.spw (wizard) file.

[0148] The end user ensures database connectivity information is set correctly. The ODBC entry field 504 with entry "sybase" points to a Sybase database running on a local machine. The username "policy" 505
with some password, shown as "******" 506 have been preinstalled.

[0149] The end user presses the Run button 507 and the .dmp file is processed through the policy specification file 105 placing the output data into the database 104.

[0150] Look at the Results Using Query Tool

[0151] The end user starts the query tool 135 by double clicking on a query tool shortcut on the desktop. In the preferred embodiment, a window such as depicted in FIG. 6 opens.

[0152] The end user presses a "Network Events" button 601 and the dialog box depicted in FIG. 7 appears. FIG. 7 is a dialog box that allows the end user to enter login information for the database 104.

[0153] Here the end user enters the same username and password as was used in policy monitor 100 and connects to a database 104 named Policy on localhost.

[0154] When connected, the screen shown in FIG. 8 appears. FIG. 8 is a dialog box that allows the user to select which processed network data to view from database 104. The topmost entry in the "Execution Run" pull-down contains most recent data was added to the database 104. In this case it is current processing of the qs.dmp file. The end user presses the "Query" button and network event information for this run is retrieved from the database 104 and shown in as in FIG. 9.

[0155] FIG. 9 shows a queried rule view dialog box according to the preferred embodiment of the invention. FIG. 9 shows that the null.spw policy has denied all traffic. The network events having disposition Udp_Access_Denied represent DNS lookups from an internal host (10.5.63.143) to another internal host (10.5.63.6). It is assumed for this example that this is traffic conforming to policy, and therefore the end user adds a rule to the policy to permit this event.

[0156] Add a New Rule Using The Wizard

[0157] The end user returns to the policy wizard main window and presses the "Edit Rules" button which opens a dialog box as shown in FIG. 10a. FIG. 10a shows a dialog box for generating a new rule according to the invention. The end user selects the "Intranet" domain from the "Policy Domain" pull-down to add a rule for our Intranet domain. The end user types a rule name, such as Internal_Dns into the "Rule Name" field and presses the "New" button. The end user selects the communities and services to which this rule applies. For simplicity in this example, the end user wants to allow DNS from any internal nodes to any other internal nodes and therefore selects an Initiator community of hosts Inside_Nodes, a service of DNS, and a Target community of hosts Inside_Nodes. The end user then presses the "Add Selected" button for each in turn to create a rule as shown in FIG. 10b, where FIG. 10b shows a dialog box for generating a new rule according to the preferred embodiment of the invention.

[0158] Next the end user generates a new policy specification file and runs policy monitor. The end user returns to the query tool and presses the "Network Events" button again to get a new rule view dialog box. The topmost "Execution Run" is now the output from the processing just completed. The end user presses the "Query" button and can now see that DNS traffic from 10.5.63.143 to 10.5.63.6 is now conformant to the policy as shown in FIG. 10c, where FIG. 10c shows the communities of the policy specification.

[0159] Detailed Description of Components

[0160] The preferred embodiment of the invention incorporates the following components, detailed description of which follows below.

A. The Policy Generator Tool

[0161] The preferred embodiment of the invention provides a policy generator tool, or simply policy generator, equally referred to as policy wizard, that provides a level of abstraction on top of the policy language, and which simplifies the process of creating an initial policy based on gross characteristics of a network at the IP level, such as policy domains, communities of hosts, servers, subnets, firewalls.

[0162] The policy generator provides a novel mechanism for translating desired network security policy, such as corporate network security policy, into a policy specification file that can be interpreted and implemented by a policy monitor mechanism.

[0163] Building a policy with the policy wizard involves: deciding on logical divisions within the network, i.e. policy domains, grouping network nodes into logical communities, and expressing rules about which communities of hosts can provide what services to which communities of hosts.

[0164] High Level View of Policy Generation

[0165] The first step in building a basic policy is to define a high-level topology for the network. Not much detail is necessary. In the preferred embodiment of the invention, the network needs to be divided into bounded units called policy domains. In practice, the choice of a policy domain boundary is fairly obvious. Usually natural logical and physical boundaries in a network help define policy domain boundaries. For example, firewalls and routers with packet filters commonly denote the important boundaries. When defining a simple policy, it is reasonable to ignore switches, bridges, hubs, and routers that connect interior subnets.

[0166] It is suggested that policy domains be as small as required by traffic monitoring limitations and as large as specification of rules allow. Rules are written about traffic visible in a policy domain. Traffic in a policy domain is logically considered to be visible anywhere within the policy domain even though networking elements, such as, for example, switches prevent such visibility in most networks. By writing rules about traffic as though it is visible anywhere within the policy domain, the same set of rules can be applied to network traffic anywhere within the policy domain.

[0167] It has been found that if a policy domain is too small, rules need to be duplicated for each extraneous policy domain. If a policy domain is too large, then the choice of a network traffic monitoring point can become overly constrained, or the ability to detect IP spoofing and rogue routers is lost.

[0168] Identify the Policy Domains

[0169] FIG. 11 shows a high-level view of an example network. An Intranet 1101 is connected to a DMZ 1102 through a firewall 1103. The DMZ 1102, in turn, connects through a router 1104 to the Internet 1105 and through a second router 1106 to an external corporate network 1107. In this example, an end user is only expected to be able to monitor traffic in the Intranet and DMZ, so these two entities are declared to be policy domains. Rules in the policy will only apply to allowed traffic in the DMZ and Intranet. The corporate network and Internet are viewed only as communities of hosts visible from within the policy domains.

[0170] It should be appreciated that the end user could choose to declare the Internet and Corporate network to be policy domains, but, by doing so, would only create unnecessary work because the end user does not intend to monitor traffic there. Any rules generated would thus never be used.

[0171] Add Perimeter Elements

[0172] In the preferred embodiment of the invention, the point of connection of a policy domain to the outside world is known as a perimeter element. For each perimeter element the set of nodes visible through it needs to be known and, for generating rules to detect IP spoofing and rogue routers, the MAC address of the perimeter element itself needs to be known.

[0173] As an example, if an end user could sit inside a policy domain and look out through boundaries, it is probable that the end user would see a filtered version of what is on the other side. Network address translation (NAT) can change the IP addresses seen though the boundary. For example, a proxying firewall may not let the end user see anything directly beyond a single IP address at the boundary. Filters may limit the view to only a few hosts when thousands are actually present.

[0174] Define Communities

[0175] In the preferred embodiment of the invention, communities consist of sets of IP addresses. They can be expressed as, for example, individual IP addresses, ranges of addresses, or subnet masks. Additionally, communities can be composed of other communities. It is often the case that a community of nodes involves all nodes in some existing set except for a node or two. Communities are defined in terms of included elements and excluded elements.

[0176] Define Rules For Each Policy Domain

[0177] In the preferred embodiment of the invention, rules defined for a policy domain describe allowed transactions. For example, if no rules are written, the policy specifies that everything at the IP level or above is denied, although this specification is not strictly true because typically auto-generated rules that apply to IP broadcast traffic and ICMP traffic within the policy domain exist. Rules create holes in this base layer that declares all traffic illegal.

[0178] Rules are defined in terms of initiator communities, target communities, and the services allowed. Services consist of a set of port numbers and indicators of whether TCP or UDP protocols are used.

[0179] Using the Policy Generator

[0180] The preferred embodiment of the invention provides a front end for the policy generator. It provides a user interface for entering and editing a simple policy. The front end reads and writes the current state of a policy from or to an intermediate file. The currently preferred extension for the intermediate file is .spw. When a policy has been specified to the satisfaction of the end user, it is written to an intermediate policy file for processing by the policy generator backend that generates a formal policy specification file compatible with the policy monitoring system.

[0181] The front end allows the end user to edit policy domains, communities, services, and rules, to read and write the current policy from or to an intermediate file, and to process the intermediate policy file into the formal policy specification file.

[0182] The preferred embodiment of the invention allows several instances of each editing process to be open simultaneously. The interaction is intended to feel very live. Data changed in one editing process should be reflected in the contents shown in other editing processes. For example, if a community is added in one community editing process, then it is immediately available for use in all editing processes. When building a policy, entities are first created, then filled in. From the time of creation they can be used throughout the policy. Consequently, a community or policy domain does not need to be fully specified in order to be used. However, to prevent errors in backend processing, all entities should be complete before the intermediate policy file is submitted to the backend for policy specification file generation.

[0183] In the preferred embodiment, only one policy is under development at any time. The front end starts up containing a default policy that is empty except for some predefined default services. This policy can be used as a starting point or an existing policy can be read from a saved intermediate policy file.

[0184] It has been found that it is best to use simple names in developing a policy and to use a name that makes sense from a predetermined point of reference, not a fully qualified name that makes sense from any point of reference. For example, it is better to give a rule a short, descriptive name such as, "Allow_Outgoing Mail" than to give the rule a long name such as, "Allow_Mail_From_Intranet_To_Outside_Intranet".

[0185] For an in-depth understanding of the formal policy specification generated by the policy generator, or policy wizard, please refer to the section, Understanding the Wizard Generated Policy, below.

B. Collecting Packet Data

[0186] The preferred embodiment of the packet gathering component 128 is a program referred to as the harvester. It reads packets off the observed network 125 and writes them to either a packet capture file 126 or to a TCP socket that is connected to the policy monitor 100.

[0187] As an example, the harvester reads packets off the network when invoked as follows:

[0188] harvester -i eth0 -c 1000 -dump qs.dmp

[0189] In this example, 1000 packets are read from a network interface labeled `eth0` and stored in file `qs.dmp.`

[0190] The harvester can also be configured to read packet data and convert it to event data suitable for policy monitor 100. As an example, the harvester may be invoked as follows:

[0191] harvester -i eth0 -c 1000 -enc qs.dme

[0192] In this example, 1000 packets are read off the network interface labeled `eth0`, converted to event data suitable for policy monitor 100, and stored in the file `qs.dme`.

[0193] The harvester can also be configured to read packet data, convert it to event data suitable for policy monitor 100, and stream such data directly to the policy monitor in real time. As an example, the harvester may be invoked as follows:

[0194] harvester -i eth0 -c 1000 -enc 10.5.63.6:333

[0195] In this example, 1000 packets are read off the network interface labeled `eth0`, converted to event data suitable for policy monitor 100, and transmitted in a TCP network stream to port 333 on the machine with IP address 10.5.63.6. This machine and TCP port may be configured so that the policy monitor 100 reads the data and processes it.

[0196] It should be appreciated that the events are transmitted as they are processed, so that the policy monitor 100 is able to see events shortly after they occur on the observed network 125.

[0197] In this mode of operation, the policy monitor 100 is also able to pass information about policy dispositions back to the harvester. The harvester can use this information to make processing of packets more efficient. For example, if the policy monitor 100 has determined that a given network event is acceptable according to the policy, the monitor can sometimes expedite its protocol processing by skipping packets until the network event terminates.

C. Policy Monitor

[0198] The preferred embodiment of the invention provides a policy monitor component that provides a user interface, either graphical or command line, that allows the configuration of various options of the monitor, policy engine and logger.

[0199] Monitor Configuration

[0200] Monitor configuration allows the end user to configure the location of the input packet dump, policy to be used, and the specification of the monitoring point.

[0201] The Input dump file specifies the input file, in tcpdump format that is to be used.

[0202] The Policy input specifies the .spm file that contains the policy specification to be used.

[0203] The Monitoring Point is a specification of where the Input dump file was collected. This name is derived from policy domain names that are specified in the policy wizard. For example, if a packet dump was collected in a policy domain named "Intranet" then the Monitoring Point name INTRANET_MONITOR should be used.

[0204] Monitor Logging Options

[0205] The monitor logging options allow the end user control of the location and the amount of data that gets written to the backend database.

[0206] The Execution Run Comment field allows the entry of freeform text that is added to the logs in the database to help identify this particular run of policy monitor.

[0207] ODBC Name provides the name of the ODBC source to which output data will be written. The DB Username and DB password are the end user's database login information. The Save Password allows the program to save the password in the clear so that it will not need to be entered the next time the program is run.

[0208] Output Options

[0209] Output options allow the end user to specify whether the trace output from the monitor should be displayed in a console window (Output to console) or sent to a file (Output to file:).

[0210] Advanced Options

[0211] Advanced options allow more options to be set. In day to day operation, it is rare that such options need to be changed.

[0212] Advanced Monitor Configuration

[0213] An Assert DLL parameter allows specification of the name of the DLL to be used to verify condition and credential assertions. Note that if this DLL does not match the version of the policy specified then this DLL will be regenerated, overwriting the provided DLL.

[0214] A Trace Options parameter allows the end user to provide configuration of runtime trace options. This option affects the amount of output generated by the monitor. For a more efficient operation, this field should be left blank.

[0215] A Certificate Dir argument points to a directory that contains trusted CA root certificates in DER encoded form.

[0216] Advanced Packet Logging Options

[0217] The packet logging options section allows the configuration of the trace options to be provided by the low level packet monitor. The various logging options may be specified at a global level (by setting them for layer "-AII-") or individually on a per-layer basis. Again it is to be noted that specifying logging options will adversely affect the performance of the monitor.

[0218] The Site Handle parameter specifies a name that is associated with the particular company or site that is being monitored. It is used to segment a table that is used for ip-address name resolution within the output database.

[0219] Advanced Monitor Logging Options

[0220] The Disable Logging checkbox disables the writing of all logging data to the database. If logging is enabled then the remaining checkboxes provide for the enabling or disabling of the logging of network events with the given final disposition code. For example, if Disable Logging is not selected and only Policy Error selected then the only network events that are logged to the database are those that resulted in a final disposition code of POLICY.sub.--ERROR.

[0221] During normal operation information about all protocol events within a network event is logged, even those that occurred after a final disposition was reached. An Enable All Layer Logging parameter can control this feature. When set on, all protocol events are logged to the database. When not set only those protocol events that are processed before a disposition is reached are logged.

D. QueryTool

[0222] The preferred embodiment of the invention provides a query tool to examine the data that was placed in the database. The preferred query tool allows the following functions to be performed:

[0223] Examining network events, such as protocol events, that are contained within the execution runs in the database;

[0224] Examining IP Connectivity for execution runs in the database;

[0225] Editing and making user defined SQL queries to the database;

[0226] Performing forward and reverse DNS lookups (using the current DNS configuration);

[0227] Viewing policy monitoring run information from the database, and selecting a default run for further viewing;

[0228] Explicitly connecting to a specific database; and

[0229] Turning on/off IP address to hostname resolution.

E. Other Tools

[0230] The preferred embodiment of the invention provides other tools discussed below.

Compiler

[0231] In its simplest form the compiler needs just a single argument that is the input policy specification file. This form is often all that is needed while doing initial development of a policy. It should be appreciated that the compiler is rarely used in standalone form since its function, with the exception of the -r flag, is subsumed into the policy monitor component.

Example Usage

[0232] During initial development a command such as the following could be used while getting rid of syntactic and semantic errors from the policy under development:

[0233] pmsCompiler.exe security.pms

[0234] Once compiler errors are gone, the end user is ready to generate pieces that are used to run the policy monitor. For example, the end user can use the command line:

[0235] pmsCompiler.exe -d verify security.pms

[0236] that compiles the security policy, and generates a verification DLL named "verify.dll".

[0237] Compiler Options

[0238] The following arguments in Table D may be provided to the example pmsCompiler.exe.

Table D

[0239] pmsCompiler -?-r

[0240] -c <cxx-file>-d <dll-file>

[0241] <policy-file>*

[0242] -c <cxx-file>

[0243] Generate Credential and Condition assertion verification code to the named file. The suffix ".cxx" will be appended to the name that is provided. This option will rarely be used to allows the end user to look at the actual code that will be used to verify assertions.

[0244] -d <dll-file>

[0245] Generate a DLL containing the assertion verification code to the named file. The suffix ".dll" will be appended to the name that is provided. If the -d flag is used without the -c flag then the source code will be written to a temporary file. This option is often used to generate the assertion verification DLL. The alternative is to allow the runtime Policy Monitor to generate the DLL for itself.

[0246] -r

[0247] Generate a pseudo-english description of the policy to stdout. The output of this command would be a useful starting point for a policy report to a customer.

[0248] -?

[0249] Display a usage string.

[0250] <policy-file>

[0251] The required policy specification (".pms") file.

[0252] -b <db-name>

[0253] Store information about the compiled policy in the named database. db-name is the name of a user data source that has been configured within Control Panels->ODBC. This argument is rarely used. The alternative is to allow the runtime Policy Monitor to write the policy to the database if needed.

[0254] -o <output-file>

[0255] Redirect compiler messages to stdout to the named output file. Rarely used.

[0256] -t <trace-opts>

[0257] Enable debug tracing. For more specific details try providing the argument "-t ?". This option will be rarely used since it only provides information to allow debugging of the compiler itself.

[0258] -v

[0259] Use VisualC++ to preprocess macros rather than the internal preprocessor. This overrides the -n option. This option will be rarely used.

[0260] -g

[0261] Add debug trace code (i.e. printf statements) to the generated Credential and Condition verification code. The generated code will also be compiled with symbol information (the C compiler -g flag). This option will be rarely used.

[0262] -n

[0263] Do not run a preprocessor. C preprocessor macros such as #define and #include may be included within a policy file. This option specifies that the pre-compiler should not be run prior to actually compiling. This option will be rarely used.

[0264] -z

[0265] Output the dump output of the parsed policy. This output looks remarkably similar to the input file with the comments stripped and some component definitions reordered.

[0266] Network Monitor

[0267] The preferred embodiment provides a streams-based network monitor that can be run in a standalone mode independent of the policy monitor. In this way it can be used to provide a detailed, streams-based view of the network traffic, or a subset thereof. For example, run in standalone mode is desirable when a particular protocol is not supported natively by the policy monitor and an end user desires to see raw data to gain an understanding of what is going on.

[0268] It should be appreciated that a convenient way of accessing such functionality is through the query tool.

[0269] Example Usage

[0270] The following invocation of the network monitor:

[0271] mon -ev 2 -l ALL=all C:.backslash.spm.backslash.quickstart.backslas- h.qs.dmp

[0272] examines the qs.dmp file, producing extremely verbose output for event 2 only.

[0273] Table E provides a list of network monitor options according to the invention.

3TABLE E Monitor Options mon [-log LAYER[=[-]option1,[-]option2...]]* [-n npkt] [-skip pkt] [-until endpkt] [-ev eventID] [-untilev eventid] [-justev eventid] [-noclients] dump_file -log -n npkt Only process the first npkt packets from the input data. -skip pkt Skip pkt packets before beginning to process the input data. -until endpkt Only process data through the packet number provided is reached -ev eventID Only process the data starting at the given eventID. -untilev eventid Only process the data through eventid. Note that in order to find the end of eventid, events with ids greater than eventid may be processed. -justev eventid Only process the data for eventid. Note that in order to find the end of eventid, events with ids greater than eventid may be processed. This option is the equivalent of -ev eventId -untilev eventId. -noclients Do not generate any output for higher level protocols such as HTTP, FTP, etc. dump_file The dump file, in tcpdump/windump format, that contains the input data.

[0274] Understanding the Wizard Generated Policy

[0275] Using the Policy Generation Wizard, a user specifies a network security policy in terms of the network services provided by certain hosts to other hosts in the network. When such policy is processed, the wizard generates a formal and more detailed description of the network security policy using the policy language. The policy language specification may then be used to analyze network traffic using the policy monitor tool. The results of this analysis can be studied using the query tool. An exemplary policy language is taught in A Declarative Language for Specifying a Security Policy, patent application Ser. No. 09/479,781 filed on Jan. 7, 2000.

[0276] Understanding the output of the preferred query tool requires understanding how the preferred wizard translates the high-level view of security policy it presents to its users into a set of policy language objects such as rules, credentials and dispositions. Understanding the policy generation process involves the following:

[0277] Understanding the predefined rules, credentials and dispositions;

[0278] Understanding the implicit rules and credentials; and

[0279] Understanding the explicit rules and credentials.

[0280] Predefined Rules, Credentials and Dispositions

[0281] Every policy generated by the wizard includes a set of predefined default rules for handling protocol events that do not conform to the user-defined policy i.e. rules that deny access, as well as rules for handling common network events not covered by the user policy. These rules and their dispositions are shown in Table F

[0282] and Table G, and further discussed below.

4 TABLE F Rule Protocol-Action Disposition Ip_Deny IP-all Ip_Access_Denied Icmp_Deny ICMP-all Icmp_Access_Denied Udp_Deny UDP-all Udp_Access_Denied Tcp_Deny TCP-all Tcp_Access_Denied Http_Deny HTTP-all Http_Access_Denied Ftp_Deny FTP-all Ftp_Access_Denied Ssl_Deny SSL-all Ssl_Access_Denied Ssh_Deny SSH-all Ssh_Access_Denied

[0283] Table G shows the default rules for all the protocols supported by the policy monitor. The policy engine selects these rules when no other rule can be found that is satisfied by the protocol event.

5TABLE G Disposi- Rule Protocol-Action tion Ip_Deny_Pure_Ip IP-PROTOCOL_UNKNOWN Deny.sub.-- Pure_Ip Tcp_Missed_Connections TCP-MISSED_CONNECT Warn.sub.-- Missed.sub.-- Tcp.sub.-- Connect Ftp_Ignore_Data_ FTP-DATA_OPEN ok Connections

[0284] Table H below shows rules that cover protocol events not addressed by the wizard's user interface. These are well understood events that can be separated from those handled by the default rules. Ip_Deny_Pure_Ip is assigned to IP associations whose payload is not one of the three well-known IP-based protocols (ICMP, UDP and TCP). Tcp_Missed_Connections is assigned to network events where the establishment of the TCP connection was not witnessed by the policy monitor. Ftp_Ignore_Data_Connections is assigned to all FTP data connections which, from a security policy monitoring perspective, can be safely ignored. It is noted that the preferred policy wizard generates other rules to deal with common protocol events as discussed below.

[0285] Table H shows the predefined dispositions used by all the rules in the generated policy. Associated with each disposition are its disposition code and severity, which may be used in the query tool to filter network events.

6TABLE H Disposition Disposition Code Disposition Severity ok OK None policy-error POLICY_ERROR CRITICAL Ip_Access_Denied ACCESS_DENIED HIGH Deny_Pure_Ip ACCESS_DENIED HIGH Monitor_Broadcasts OK MONITOR Icmp_Access_Denied ACCESS_DENIED HIGH Monitor_Icmp OK MONITOR Udp_Access_Denied ACCESS_DENIED HIGH Tcp_Access_Denied ACCESS_DENIED HIGH Warn_Missed_Tcp_Connect OK WARNING Ftp_Access_Denied ACCESS_DENIED HIGH Http_Access_Denied ACCESS_DENIED HIGH Ssl_Access_Denied ACCESS_DENIED HIGH Ssh_Access_Denied ACCESS_DENIED HIGH

[0286] It should be noted that ok and policy-error are actually built-in dispositions in the policy language. If policy-error is encountered it indicates an error in the processing of either the policy or the network traffic data by the policy monitor.

[0287] The meaning of the other dispositions is explained later in this document in the context of the rules in which they are used.

[0288] Finally, the wizard includes a set of predefined credentials that are combined with dynamically generated credentials and used in implicitly generated rules:

[0289] _Multicast_Addresses--a set of commonly used IP multicast addresses;

[0290] _Local_Broadcast_Address--the IP address used for non-directed local broadcasts (255.255.255.255); and

[0291] _Zero_lp_Address--a zero-valued IP address (0.0.0.0), commonly used by BOOTP clients;

[0292] It is noted that the double underscore prefix in these credential names is used to ensure that there aren't any name conflicts with credentials generated to represent user-defined communities and services.

[0293] Explicit Rules and Credentials

[0294] Every community defined by the user results in a credential of the same name. Because the scope of a community name is that of the entire policy specification, the resulting credential names need not be massaged to ensure uniqueness.

[0295] Service names are also global in scope. Because services and communities share the same name space, every service defined in the policy results in a credential whose name is constructed by prefixing the user-supplied service name with the underscore character. Thus, for example, the Smb service is represented by a credential named_Smb.

[0296] Rule names, on the other hand, are only unique within the scope of a policy domain. Furthermore, if a user-defined rule addresses a service that is both a UDP and a TCP service, the wizard generates two rules, one for the UDP protocol and another for the TCP protocol. Thus, a rule name is constructed by prefixing the user-supplied name with the protocol name (Udp_ or Tcp_) and the policy domain name.

[0297] For example, if the user defines a rule titled Smb_Services within a policy domain named Intranet, the wizard will generate two rules, Udp_Intranet_Smb_Services and Tcp_Intranet_Smb_Services, for the UDP and TCP protocols respectively.

[0298] User-defined rules may also result in the generation of additional credentials. When defining a rule, the user provides the following information:

[0299] Zero, one or more initiator communities;

[0300] Zero, one or more services; and

[0301] Zero, one or more target communities.

[0302] If more than one initiator community are specified, the wizard generates a credential that combines these communities into a union. The credential name is constructed by appending the word _Initiator to the user-supplied rule name, prefixed by the policy domain name. Using the example above, the wizard would create a credential named Intranet_Smb Services_Initiator.

[0303] Likewise, if more than one target communities are specified, the wizard creates a credential representing their union and names it by appending the word _Target to the policy domain and rule names e.g. Intranet_Smb_Services_Target).

[0304] However, if one or more services are specified they are combined with the target credentials according to the service type. For example, the Smb service (for the SMB protocol suite) and its like-named credential include ports that are used for both TCP and UDP. Thus, for the Smb_Services rule used above, the wizard would generate the following additional credentials: Udp_Intranet_Smb_Services_Target a n d Tcp_Intranet_Smb_Services_Target. These credentials combine Intranet_Smb_Services_Target (or a single target community) with the _Smb credential and constitute the actual target credentials used in Udp_Intranet Smb_Services and Tcp_Intranet_Smb_Services respectively. It should be noted that, in many cases, the set of UDP and TCP services referenced in a rule will have little, if any overlap. Of course, if the end user does not specify any services the wizard uses the Intranet_Smb_Services_Target credential (or a single target community credential) to identify the target principal.

[0305] Implicit Rules and Credentials

[0306] For each policy domain within the policy specification, the wizard automatically generates a set of rules and credentials that define the valid IP-level traffic seen at the monitoring point within the domain. In addition, an ICMP rule is generated that handles all intradomain ICMP traffic, as well as a credential for the monitoring point in that domain.

[0307] The monitoring point credential is based on an agent descriptor string manufactured by the wizard. The agent descriptor is constructed by converting the policy domain name to uppercase and appending to it the word _MONITOR. Thus, for example, a policy domain named Intranet is assigned the agent descriptor:

[0308] INTRANET_MONITOR.

[0309] Note that this is the agent descriptor to be used in the policy monitor when analyzing data collected at this monitoring point.

[0310] The monitoring point credential itself is named by appending the word _Monitors to the policy domain's name. In the example above, the credential would be named Intranet_Monitors.

[0311] The wizard segregates all intradomain ICMP traffic (common on an enterprise network) by means of a rule that assigns it the disposition Monitor_Icmp. The rule is named by combining the protocol name with the domain name using the word _Within. For example, in the Intranet policy domain the rule would be named Icmp_Within_Intranet.

[0312] IP traffic is described by a set of rules that systematically enumerate all valid IP-level traffic within the policy domain, between hosts in the policy domain and external hosts, and between external hosts through the policy domain (when more than one perimeter element is present). Most of these rules provisionally allow IP traffic, letting the subsequent protocol layers (ICMP, UDP, TCP, etc.) determine if the traffic is indeed allowed either by a user-defined (explicit) rule or by a predefined rule.

[0313] The first IP rule provisionally allows all intradomain IP traffic. It is named by combining the protocol name with the domain name using the word _Within (e.g., Ip_Within_Intranet). In the absence of a higher-level protocol within an intradomain IP association, the rule assigns the network event a disposition of Deny_Pure_Ip (i.e., its final outcome).

[0314] The intradomain IP rule uses the policy domain's defining community as its target principal. However, it generates another credential to be used as the initiator. This credential combines the defining community with the predefined credential for zero-valued IP addresses (_Zero_Ip_Address). The generated credential is named by appending the word _Initiator to the generated rule name (e.g., Ip Within_Intranet_Initiator.

[0315] Another intradomain IP rule is used to segregate typical broadcast and multicast traffic within an enterprise network. It is named by combining the protocol name with the domain name using the words _Broadcasts_Within (e.g., Ip_Broadcasts_Within_Intranet). Its initiator principal is the same as that used for the general intradomain traffic e.g. Ip_Within_Intranet_Initiator). Its target is a new credential constructed by combining the predefined credentials_Multicast_Addresses and _Local_Broadcast_Address with the directed broadcast addresses for all the subnets within the policy domain's defining community. The new credential is named by appending the word _Target to the rule name e.g. Ip_Broadcasts_Within_Intranet_Target).

[0316] The intradomain broadcast and multicast traffic is assigned the disposition Monitor_Broadcasts.

[0317] Traffic between hosts in the policy domain and external hosts is described by a set of rules whose complexity depends on how much information the user supplied about the topology of the network. Specifically, it depends on how many perimeter elements were specified and on whether or not the interface addresses, i.e. MAC addresses, of the perimeter elements are included in the policy specification.

[0318] If there are external communities associated with at least one perimeter element for which the interface address is not known, the wizard generates a credential combining all such communities in a single union unless there is only one such community, in which case its credential already exists. This credential is named by combining the policy domain name with the string _External Communities (e.g., Intranet_External_Communities).

[0319] The wizard then generates two rules defining the traffic between hosts internal to the policy domain and these external communities. The wizard names these rules by combining the protocol name with the domain name and the string _To_External_Communities or _External_Communities_To, depending on the direction of the IP traffic (e.g., Ip_Intranet_To_External_Communities for outbound traffic and Ip_External_Communities_To_Intranet for inbound traffic).

[0320] The credentials used alternately as the initiator and target principals for these rules are the policy domain's defining community and the aforementioned credential for the external communities. The rules provisionally allow the IP traffic to flow, subject to other rules for higher level protocols. In the absence of a higher-level protocol within the network event, the rule assigns it a disposition of Deny_Pure_Ip, i.e. its final outcome.

[0321] External communities visible through one or more perimeter elements whose interface addresses are known, are handled by a separate set of rules, two per perimeter element. For each perimeter element, the wizard starts by creating a credential that combines the credential(s) for the external community(ies) visible through it with the perimeter element's interface address. Such credential is named by combining the domain name with the perimeter element name and the string Communities. For example, external communities visible through a perimeter element named Firewall would be described by a credential named Intranet_Firewall_Communities.

[0322] The wizard then generates two rules defining the traffic between hosts internal to the policy domain and the external communities visible through this perimeter element. The wizard names these rules by combining the protocol name, the domain name, the perimeter element name and the word _To (e.g., Ip_Intranet_To_Intranet_Firewall for outbound traffic and Ip_Intranet_Firewall_To_Intranet for inbound traffic).

[0323] The credentials used alternately as the initiator and target principals for these rules are the policy domain's defining community and the aforementioned credential for the external communities. The rules provisionally allow the IP traffic to flow, subject to other rules for higher level protocols. In the absence of a higher-level protocol within the network event, the rule assigns it a disposition of Deny_Pure_Ip, i.e., its final outcome.

[0324] Finally, if there is more than one perimeter element associated with the policy domain, the wizard generates rule-pairs that describe the traffic between external communities visible through specific perimeter elements as well as external communities visible through any perimeter element, i.e. those without associated interface addresses. The rules are named by combining the names of each pair of perimeter elements with the protocol name, the policy domain name and with the word _To, in the case of addressable perimeter elements, or with the string _External_Communities, for all other external communities. An additional rule is generated to cover traffic between external communities not associated with an addressable perimeter element and is named by combining the protocol name with the domain name and the string _Between_External_Communities.

[0325] Thus, if the Intranet domain used as an example in this section were to have a second (addressable) perimeter element named Router and a third non-addressable perimeter element (whose name is unimportant), the wizard would generate the following rules to cover all traffic amongst their respective external communities:

[0326] Ip_Intranet_Firewall_To_Intranet_Router

[0327] Ip_Intranet_Router_To_Intranet_Firewall

[0328] Ip_Intranet_Firewall_To_External_Communities

[0329] Ip_External_Communities_To_Intranet_Firewall

[0330] Ip_Intranet_Router_To_External_Communities

[0331] Ip_External_Communities_To_Intranet Router

[0332] Ip_Intranet_Between_External_Communities

[0333] Table I and Table J summarize all the implicit rules and credentials generated for the example policy domain Intranet. The policy domain includes two perimeter elements with a specified interface address (Firewall and Router) and a third non-addressable perimeter element.

7TABLE I Credential Comment Intranet_ Uses agent descriptor INTRANET_MONITOR Monitors Ip_Within.sub.-- Defining community plus zero-valued IP address Intranet_Initiator Ip_Broadcasts.sub.-- Combines standard multicast addresses with local Within_Intra- broadcast and directed broadcast addresses net.sub.--Target Intranet.sub.-- Combines all external communities not associated with External.sub.-- addressable perimeter elements Communities Intranet.sub.-- Combines all external communities visible through the Firewall.sub.-- Firewall perimeter element Communities Intranet.sub.-- Combines all external communities visible through the Router.sub.-- Router perimeter element Communities

[0334]

8TABLE J Credentials Disposition (I-Initiator (I-Immediate Rule T-Target) F-Final) Ip_Within_Intranet I: Ip_Within_Intranet_Initiator I: continue T: Intranet F: Deny_Pure_Ip Ip_Broadcasts_Within_Intranet I: Ip_Within_Intranet_Initiator I: T: Monitor_Broadcast Ip_Broadcasts_Within_Intranet.sub.-- s Target Icmp_Within_Intranet I: none (ignore) I: Monitor_Icmp T: none (ignore) Note: uses Ip_Within_Intranet as prerequisite Ip_Intranet_To_External.sub.-- I: Intranet I: continue Communities T: Intranet_External.sub.-- F: Deny_Pure_Ip Communities Ip_External_Communities_To.sub.-- I: Intranet_External_Communities I: continue Intranet T: Intranet F: Deny_Pure_Ip Ip_Intranet_To_Intranet_Firewall I: Intranet I: continue T: Intranet_Firewall.sub.-- F: Deny_Pure_Ip Communities Ip_Intranet_Firewall_To_Intranet I: Intranet_Firewall_Communities I: continue T: Intranet F: Deny_Pure_Ip Ip_Intranet_To_Intranet_Router I: Intranet I: continue T: Intranet_Router.sub.-- F: Deny_Pure_Ip Communities Ip_Intranet_Router_To_Intranet I: Intranet_Router_Communities I: Continue T: Intranet F: Deny_Pure_Ip Ip_Intranet_Firewall_To_Intranet.sub.-- I: Intranet_Firewall_Communities I: continue Router T: Intranet_Router.sub.-- F: Deny_Pure_Ip Communities Ip_Intranet_Router_To_Intranet.sub.-- I: Intranet_Router_Communities I: continue Firewall T: Intranet_Firewall.sub.-- F: Deny_Pure_Ip Communities Ip_Intranet_Firewall_To_External.sub.-- I: Intranet_Firewall_Communities I: Continue Communities T: Intranet_External.sub.-- F: Deny_Pure_Ip Communities Ip_External_Communities_To.sub.-- I: Intranet_External_Communities I: continue Intranet_Firewall T: Intranet_Firewall.sub.-- F: Deny_Pure_Ip Communities Ip_Intranet_Router_To_External.su- b.-- I: Intranet_Router_Communities I: Continue Communities T: Intranet_External.sub.-- F: Deny_Pure_Ip Communities Ip_External_Communities_To.sub.-- I: Intranet_External_Communities I: continue Intranet_Router T: Intranet_Router_Communities F: Deny_Pure_Ip Ip_Intranet_Between_External.sub.-- I: Intranet_External_Communities I: continue Communities T: Intranet_External.sub.-- F: Deny_Pure_Ip Communities

[0335] Logging and Reporting Modules

[0336] The preferred embodiment of the invention provides logging and reporting modules, as described herein with reference to FIG. 1a. As the policy engine module 102 reaches dispositions on network events, it passes the network event object to the logging module 103.

[0337] The preferred embodiment of the invention also provides an alarm script 155. As the policy engine module 102 reaches dispositions on network events of a certain disposition severity, for example, CRITICAL or HIGH, the alarm script is invoked to provide expedited alerting of the disposition.

[0338] The following algorithm is used to enter the data into the database 104.

[0339] During initialization of the logging module 103, the database 104
is tested to see if it contains a policy that matches the MD5 hash of the policy 105 currently being used by the policy engine 102. If no such policy is found then the policy details are added to the database 104;

[0340] with each network event passed to the logging module 103, if logging of network events is enabled, then:

[0341] if the final disposition of the network event matches one of the list of dispositions that is to be logged, then:

[0342] add the network event to the buffer of network events, flushing the buffer to the database 104 if it is full;

[0343] loop through each of the protocol events contained in the network event;

[0344] if the initiator and responder principals have not been already added to the database 104 then do so, caching the database keys for later use; and

[0345] add the protocol event to the buffer of network events, flushing the buffer to the database 104 if it is full.

[0346] On a periodic basis report statistics 161 are sent across a secure channel to a secure, customer accessible server 162. The preferred embodiment of the invention uses the following algorithm.

[0347] A report script 160 described is used to generate a report 161 for the configured or predetermined time period. An example of a list of preferred acquired or calculated statistics or intermediate steps is contained in Table K below;

[0348] The report 161 is then packaged using the tar command and PGP to encrypt the resulting file using the public key of a recipient email account; and

[0349] This encrypted file is then emailed to the recipient email account.

[0350] It should be appreciated that an equally preferred embodiment performs name resolution on packet data after the packet data has been collected, rather than concurrent with collecting the packet data. An advantage to such name resolution technique is that name resolution after collection is removed from real-time processing, thereby rendering name resolution more efficient.

[0351] On the receiving secure server 162 the following algorithm is invoked on the received email message.

[0352] PGP is used to decrypt the received encrypted tar file;

[0353] Tar is used to extract the report data;

[0354] The report data is then processed to link the report into the reporting website 164 for the client; and

[0355] Any supplied protocol event data is then stored in a reporting database 165.

[0356] Upon accessing the reporting website 164 the client is able to peruse the reports that have been generated, access the protocol event data stored in the database 165 via a cgi script.

9TABLE K Generate network events in subsidiary web files, based on execution run; Generate network events table, Generate table for URL's and status codes; Find events of interest; Check for all execution runs being in sequence; Give best optimization for queries; Compute number of events and number of exceptions; Apply definitions of log severity and disposition code in order of criticality; Apply query to several execution runs at a time, collect results; Select key disposition and key policy rule first, to be able to find distinct disposition and policy rule; Determine sort order for disposition and policy rule table; and Generate a list of dispositions in the selected events, counting how many events were generated by each.

II. Automated Generation of an English Language Representation of a Formal Network Security Policy Specification

[0357] The preferred embodiment of the invention uses a formal specification of network security policy that is to be enforced on a network. This specification provides a precise, compact description of network security policy. However, it is difficult for a layperson to understand. In order to allow comprehension of the policy by non-technical staff within a user's organization the parser module (FIG. 1 150) is used to generate an English language description of the policy. This description is simple enough to be understood, yet captures the salient details of the policy.

[0358] The preferred embodiment of the invention provides the following algorithm for generating the English language representation. The algorithm comprises the following:

[0359] Loading the policy into the parser from its text representation; and

[0360] Looping through all supported protocols, from the highest level protocols to the lowest;

[0361] Sorting the rules for this protocol into ranked order; and

[0362] Looping through these rules from the highest ranking to the lowest;

[0363] Generating a text description of the rule using the algorithm below. If an HTML flag has been set then format the text into a HTML table; and

[0364] Append this description to a collection of descriptions already generated.

[0365] The preferred embodiment of the invention provides the following rule algorithm to generate an English language representation of a single policy language rule. The algorithm is described with reference to FIG. 12. The algorithm outputs the name of the rule at hand (2001). It then proceeds to output the agent's name (2002), where the agent is the subject network monitor(s) to which the policy applies. The algorithm then loops through all protocol and action combinations (2003). If the action is to be ignored (2004), then the rule applies to the whole protocol (2005). Otherwise, the rule applies to certain actions only (2014). The algorithm then looks at the immediate outcome for the rule (2006). The algorithm then outputs the corresponding directive for the outcome (2007). If any conditions exist on the disposition, then the algorithm outputs the conditions (2008). The algorithm looks at the final outcome (2011), then outputs the corresponding final outcome of the rule (2012). If any conditions exist on the disposition, then the algorithm outputs the conditions (2013). If the rule applies to a particular initiator or target, then the algorithm outputs the initiator or target name (2009). Otherwise, the algorithm outputs a general inclusive name, such as, for example, "anyone." The algorithm then checks for prerequisites (2010). If any are discovered, the algorithm then outputs such prerequisites.

[0366] For an example of the rule algorithm discussed above, Table L below shows code to the example implementation.

10 TABLE L if (isBuiltin( )) return; Bool processedImmediate = false; Bool immediateDefaultContinu- e = false; Bool capitalize = true; string str; string protocol; // output the table row start if (html) str = ".backslash.n<tr><p>"; else str = ".backslash.n.backslash.n"; // output the rule name if (html) str += "<TD WIDTH=.backslash."10%.backslash." VALIGN=.backslash."TOP.backslash."><B>" + getName( ) + "<a name = /"" + getName( ) + ".backslash."></a></B>&l- t;/TD>"; else str += "Rule " + getName( ) + ";"; // output the agent name string agentName; if (getAgent( ) == 0) agentName = "All Monitors"; else agentName = getAgent( )->getName( ); if (html) str += "<TD WIDTH=.backslash."5%.backslash." VALIGN=.backslash."TOP.backslash- .">" + agentName + "</TD>", // start the cell for the description if (html) str += "<TD WIDTH=.backslash."85%.backslash." VALIGN=/"TOP/">"; // loop through the protocol and action combinations Bool first = true, for (PrsUnion::const_iterator t0 = _protocol->begin( ), t0 != _protocol->end( ); t0++) { for (PrsUnion::const_iterator t2 = _action->begin( ); t2 != _action->end( ); t2++) { if (first) first = false, else protocol += ","; // if the action is ignore then it applies to the whole protocol if ((t2)->getStringRepresentation( ) !=PrsConst::META_IGNORE) protocol += (*t0)->getStringRepresentation( ) + "-" + (*t2)->getStringRepresentation( ) + " "; else protocol += (*t0)->getStringRepresentation( ) + " "; } } // look at the outcome to figure what we do with this traffic // is there an immediate clause if (_immediate != 0) { // output text based on the code string code = _immediate->getDefault( )->getCode( ); if (code == PrsConst::DISPCODE_OK) { capitalize ? str += "Allow" : str += "allow"; capitalize = false; } else if (code == PrsConst::DISPCODE_CONTINUE) { if (_final->getDefault( )->getCode( ) == PrsConst::DISPCODE_OK) capitalize ? str += "Provisionally allow" : str += "provisionally allow"; else if (_final->getDefault( )->getCode( ) == "POLICY_ERROR") ;// say nothing... this is the default else capitalize ? str += "Provisionally deny" str += "provisionally deny"; immediateDefaultContinue = true, } else { capitalize ? str += "Deny" str += "deny"; capitalize = false; } str += protocol, if ((_immediate->getGuards( )) != 0 && (_immediate->getGuards( )->size( ) != 0)) /* KGS && !immediateDefaultContinue */ { if (_immediate->getGuards( )->size( ) == 1) str += "with condition ("; else str += "with conditions ("; first = true; for (std::vector<PrsGuardedDisposition*>- ;::const_iterator cond = _immediate->getGuards( )->begin( ); cond != _immediate->getGuards( )->end( ); cond++) { if (first) first = false; else str += ",", if (html) str += "<.vertline.>"; str += (*cond)->getGuard( )->getName( ); if (html) str += "<.vertline.>"; } str += "),"; } processedImmediate = true; } // is there a final clause if (final != 0) { if (!processedImmediate) { // output text based on the code string code = _final->getDefault( )->getCode( ); if (code == PrsConst::DISPCODE_OK) { capitalize ? str += "Provisionally allow" : str += "provisionally allow"; capitalize = false; } else if (code == "POLICY_ERROR") ;// say nothing... this is the default else } capitalize ? str += "Provisionally deny" : str += "provisionally deny"; capitalize = false; { str += protocol; if ((_final->getGuards( )) != 0 && (_final->getGuards( )->size( ) != 0)) { if (_final->getGuards( )->size( ) == 1) str += "with condition ("; else str += "with conditions ("; Bool first = true; for (std::vector<PrsGuardedDisposition*>::const_iterator cond = _immediate->getGuards( )->begin( ); cond != _immediate->getGuards( )->end( ), cond++) { if (first) first = false; else str += ","; if (html) str += "<.vertline.>"; str += (*cond)->getGuard( )->getName( ); if (html) str += "</.vertline.>"; } str += "),"; } } else { // output text based on the code string code = _final->getDefault( )->getCode( ); if (!immediateDefaultContinue) { if (code == PrsConst::DISPCODE_OK) str += "but provisionally allow"; else if (code == "POLICY_ERROR") ;// say nothing... this is the default else str += "but provisionally deny", } if (_final->getGuards( )) != 0 && (_final->getGuards( )->size( ) != 0)) { str += "with conditions ("; Bool first = true; for (std::vector<PrsGuardedDisposition*>- ;::const_iterator cond = _immediate->getGuards( )->begin( ); cond != _immediate->getGuards( )->end( ); cond++) { if (first) first = false; else str += ","; if (html) str +="<.vertline.>"; str += (*cond)->getGuard( )->getName( ); if (html) str+= "</.vertline.>"; } str += "),", } } } if (html) str += "from <.vertline.>" + (_initiator->getCredential( ) ? initiator->getCredential( )->getName( ) : "anyone") + </.vertline.> to <.vertline.>" + (_target->getCredential( ) ? _target->getCredential( )->getName( ) : "anyone") + "</.vertline.>"; else str += "from" + (_initiator->getCredential( ) ? _initiator->getCredential( )->getName( ) : "anyone") + " to " + ( target->getCredential( ) ? _target->getCredential( )->getName( ) : "anyone"); if (getPrerequisite( ) != 0) { str += ", provided that "; Bool first = true; for (vector<const PrsRule*>::const_iterator t3 = _prerequisite->begin( ); t3 != _prerequisite->end( ); t3++) { if (first) first = false; else str += " or "; if (html) str += "<.vertline.><a href=.backslash."#" + (*t3)->getName( ) + ".backslash.">" + (*t3)->getName( ) + "</a></.vertline.>- ;"; else str += (*t3)->getName( ); } str += " is true. "; } // start the cell for the description if (html) str += "</TD></TR>"; else str += " (Agent " + agentName + ")."; ostm << str.c_str( );

[0367] For an example of an output file generated by the main algorithm discussed above, Table M shows the example of the output in table format. (For an example of a policy specification file that can be used as input into the main algorithm discussed above, refer to Table R below.)

11TABLE M Rules for protocol HTTP Http Blocked_Service_Violation All Deny HTTP from anyone to anyone, Monitors provided that Tcp Blocked Services is true Http_Deny All Deny HTTP from anyone to anyone Monitors Rules for protocol FTP Ftp_Blocked_Service_Violation All Deny FTP from anyone to anyone, Monitors provided that Tcp Blocked Services is true. Ftp_Deny All Deny FTP from anyone to anyone Monitors Ftp_Anonymous_Authentication All Allow FTP-CONTROL_AUTHENTICATE Monitors with condition (Authentication_Rejected), from Anon_User to anyone Ftp_Validate_Password All Allow FTP-CONTROL_AUTHENTICATE Monitors with conditions (Authentication_Rejected Strong_Password), from anyone to anyone Ftp_Ignore_Data_Connections All Allow FTP-DATA_OPEN from anyone to Monitors anyone Rules for protocol SSH Ssh_Validate_Handshake All Monitors Allow SSH-HANDSHAKE, SSH- SESSION _ABORTED with conditions (Ssh_Authentication_Failed Ssh_Authentication_Aborted Ssh_Secure_Authentication_Modes), from anyone to anyone Ssh_Blocked_Service_Violation All Monitors Deny SSH from anyone to anyone, provided that Tcp Blocked Services is true. Ssh_Deny All Monitors Deny SSH from anyone to anyone Rules for protocol SSL Ssl_Validate_Handshake All Monitors Allow SSL-HANDSHAKE with conditions