Symantec Scan Engine Software Developer s Guide

Transcription

1 Symantec Scan Engine Software Developer s Guide

2 2 Symantec Scan Engine Software Developer s Guide The software described in this book is furnished under a license agreement and may be used only in accordance with the terms of the agreement. Documentation version 5.0 Copyright Notice Copyright 2005 Symantec Corporation. All Rights Reserved. Any technical documentation that is made available by Symantec Corporation is the copyrighted work of Symantec Corporation and is owned by Symantec Corporation. NO WARRANTY. The technical documentation is being delivered to you AS-IS, and Symantec Corporation makes no warranty as to its accuracy or use. Any use of the technical documentation or the information contained therein is at the risk of the user. Documentation may include technical or other inaccuracies or typographical errors. Symantec reserves the right to make changes without prior notice. No part of this publication may be copied without the express written permission of Symantec Corporation, Stevens Creek Blvd., Cupertino, CA Trademarks Symantec and the Symantec logo are U.S. registered trademarks of Symantec Corporation. CarrierScan Server, Bloodhound, LiveUpdate, NAVEX, Symantec AntiVirus, and Symantec Security Response are trademarks of Symantec Corporation. Sun, Sun Microsystems, the Sun logo, Sun Enterprise, Java, Ultra, and Solaris are trademarks or registered trademarks of Sun Microsystems, Inc., in the United States and other countries. SPARC is a registered trademark of SPARC International, Inc. Products bearing SPARC trademarks are based on an architecture developed by Sun Microsystems, Inc. Microsoft, ActiveX, Windows, Windows NT, and the Windows Logo are registered trademarks of Microsoft Corporation in the United States and other countries. Pentium is a registered trademarks of Intel Corporation. Red Hat is a registered trademark of Red Hat Software, Inc., in the United States and other countries. Linux is a registered trademark of Linus Torvalds. NetApp, Data ONTAP, NetCache, Network Appliance, and Web Filer are registered trademarks or trademarks of Network Appliance, Inc., in the United States and other countries. Adobe, Acrobat, and Acrobat Reader are trademarks of Adobe Systems Incorporated. THIS PRODUCT IS NOT ENDORSED OR SPONSORED BY ADOBE SYSTEMS INCORPORATED, PUBLISHERS OF ADOBE ACROBAT. Other brands and product names mentioned in this manual may be trademarks or registered trademarks of their respective companies and are hereby acknowledged. A modified version of a freeware SNMP library is used in this software. This software is Copyright 1988, 1989 by Carnegie Mellon University All Rights Reserved. Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of CMU not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. CMU software disclaimer: CMU DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL CMU BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. A set of Unicode handling libraries is used in this software. This software is Copyright (c) International Business Machines Corporation and others. All rights reserved.

3 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the Software ), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, provided that the above copyright notice(s) and this permission notice appear in all copies of the Software and that both the above copyright notice(s) and this permission notice appear in supporting documentation. Except as contained in this notice, the name of a copyright holder shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization of the copyright holder. IBM software disclaimer: THE SOFTWARE IS PROVIDED AS IS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. Printed in the United States of America

4 4 Technical support Licensing and registration Contacting Technical Support As part of Symantec Security Response, the Symantec global Technical Support group maintains support centers throughout the world. The Technical Support group s primary role is to respond to specific questions on product feature/ function, installation, and configuration, as well as to author content for our Web-accessible Knowledge Base. The Technical Support group works collaboratively with the other functional areas within Symantec to answer your questions in a timely fashion. For example, the Technical Support group works with Product Engineering as well as Symantec Security Response to provide Alerting Services and Virus Definition Updates for virus outbreaks and security alerts. Symantec technical support offerings include: A range of support options that give you the flexibility to select the right amount of service for any size organization Telephone and Web support components that provide rapid response and up-to-the-minute information Upgrade insurance that delivers automatic software upgrade protection Content Updates for virus definitions and security signatures that ensure the highest level of protection Global support from Symantec Security Response experts, which is available 24 hours a day, 7 days a week worldwide in a variety of languages for those customers enrolled in the Platinum Support Program Advanced features, such as the Symantec Alerting Service and Technical Account Manager role, offer enhanced response and proactive security support Please visit our Web site for current information on Support Programs. The specific features available may vary based on the level of support purchased and the specific product that you are using. If the product that you are implementing requires registration and/or a license key, the fastest and easiest way to register your service is to access the Symantec licensing and registration site at Alternatively, you may go to select the product that you wish to register, and from the Product Home Page, select the Licensing and Registration link. Customers with a current support agreement may contact the Technical Support group via phone or online at Customers with Platinum support agreements may contact Platinum Technical Support via the Platinum Web site at www-secure.symantec.com/platinum/.

5 5 When contacting the Technical Support group, please have the following: Product release level Hardware information Available memory, disk space, NIC information Operating system Version and patch level Network topology Router, gateway, and IP address information Problem description Error messages/log files Troubleshooting performed prior to contacting Symantec Recent software configuration changes and/or network changes Customer Service To contact Enterprise Customer Service online, go to select the appropriate Global Site for your country, then choose Service and Support. Customer Service is available to assist with the following types of issues: Questions regarding product licensing or serialization Product registration updates such as address or name changes General product information (features, language availability, local dealers) Latest information on product updates and upgrades Information on upgrade insurance and maintenance contracts Information on Symantec Value License Program Advice on Symantec's technical support options Nontechnical presales questions Missing or defective CD-ROMs or manuals

6 Symantec Software License Agreement Symantec Scan Engine Software Developer s Guide SYMANTEC CORPORATION AND/OR ITS SUBSIDIARIES ("SYMANTEC") IS WILLING TO LICENSE THE SOFTWARE TO YOU AS AN INDIVIDUAL, THE COMPANY, OR THE LEGAL ENTITY THAT WILL BE UTILIZING THE SOFTWARE (REFERENCED BELOW AS "YOU" OR "YOUR") ONLY ON THE CONDITION THAT YOU ACCEPT ALL OF THE TERMS OF THIS LICENSE AGREEMENT. READ THE TERMS AND CONDITIONS OF THIS LICENSE AGREEMENT CAREFULLY BEFORE USING THE SOFTWARE. THIS IS A LEGAL AND ENFORCEABLE CONTRACT BETWEEN YOU AND THE LICENSOR. BY OPENING THIS PACKAGE, BREAKING THE SEAL, CLICKING THE "AGREE" OR "YES" BUTTON OR OTHERWISE INDICATING ASSENT ELECTRONICALLY, OR LOADING THE SOFTWARE, YOU AGREE TO THE TERMS AND CONDITIONS OF THIS AGREEMENT. IF YOU DO NOT AGREE TO THESE TERMS AND CONDITIONS, CLICK THE "I DO NOT AGREE" OR "NO" BUTTON OR OTHERWISE INDICATE REFUSAL AND MAKE NO FURTHER USE OF THE SOFTWARE. 1. License: The software and documentation that accompanies this license (collectively the "Software") is the proprietary property of Symantec or its licensors and is protected by copyright law. While Symantec continues to own the Software, You will have certain rights to use the Software after Your acceptance of this license. This license governs any releases, revisions, or enhancements to the Software that the Licensor may furnish to You. Except as may be modified by an applicable Symantec license certificate, license coupon, or license key (each a "License Module") that accompanies, precedes, or follows this license, and as may be further defined in the user documentation accompanying the Software, Your rights and obligations with respect to the use of this Software are as follows. You may: A. use the number of copies of the Software as have been licensed to You by Symantec under a License Module. 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If no License Module accompanies, precedes, or follows this license, You may make one copy of the Software You are authorized to use on a single computer; B. make one copy of the Software for archival purposes, or copy the Software onto the hard disk of Your computer and retain the original for archival purposes; C. use the Software on a network, provided that You have a licensed copy of the Software for each computer that can access the Software over that network; D. use the Software in accordance with any written agreement between You and Symantec; and E. after written consent from Symantec, transfer the Software on a permanent basis to another person or entity, provided that You retain no copies of the Software and the transferee agrees in writing to the terms of this license. You may not: A. copy the printed documentation that accompanies the Software; B. sublicense, rent, or lease any portion of the Software; reverse engineer, decompile, disassemble, modify, translate, make any attempt to discover the source code of the Software, or create derivative works from the Software; C. use the Software as part of a facility management, timesharing, service provider, or service bureau arrangement; D. use a previous version or copy of the Software after You have received and installed a disk replacement set or an upgraded version. Upon upgrading the Software, all copies of the prior version must be destroyed; E. use a later version of the Software than is provided herewith unless You have purchased corresponding maintenance and/or upgrade insurance or have otherwise separately acquired the right to use such later version; F. use, if You received the software distributed on media containing multiple Symantec products, any Symantec software on the media for which You have not received permission in a License Module; nor G. use the Software in any manner not authorized by this license. 2. Content Updates: Certain Software utilize content that is updated from time to time (including but not limited to the following Software: antispam software utilize updated antispam rules; antivirus software utilize updated virus definitions; content filtering software utilize updated URL lists; some firewall software utilize updated firewall rules; policy compliance software utilize updated policy compliance updates; and vulnerability assessment products utilize updated vulnerability signatures; these updates are collectively referred to as "Content Updates"). You shall have the right to obtain Content Updates for any period for which You have purchased maintenance, except for those Content Updates that Symantec elects to make available by separate paid subscription, or for any period for which You have otherwise separately acquired the right to obtain Content Updates. Symantec reserves the right to designate specified Content Updates as requiring

7 purchase of a separate subscription at any time and without notice to You; provided, however, that if You purchase maintenance hereunder that includes particular Content Updates on the date of purchase, You will not have to pay an additional fee to continue receiving such Content Updates through the term of such maintenance even if Symantec designates such Content Updates as requiring separate purchase. This License does not otherwise permit the licensee to obtain and use Content Updates. 3. Limited Warranty: Symantec warrants that the media on which the Software is distributed will be free from defects for a period of thirty (30) days from the date of delivery of the Software to You. Your sole remedy in the event of a breach of this warranty will be that Symantec will, at its option, replace any defective media returned to Symantec within the warranty period or refund the money You paid for the Software. Symantec does not warrant that the Software will meet Your requirements or that operation of the Software will be uninterrupted or that the Software will be error-free. TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, THE ABOVE WARRANTY IS EXCLUSIVE AND IN LIEU OF ALL OTHER WARRANTIES, WHETHER EXPRESS OR IMPLIED, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NONINFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS. THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS. YOU MAY HAVE OTHER RIGHTS, WHICH VARY FROM STATE TO STATE AND COUNTRY TO COUNTRY. 4. Disclaimer of Damages: SOME STATES AND COUNTRIES, INCLUDING MEMBER COUNTRIES OF THE EUROPEAN ECONOMIC AREA, DO NOT ALLOW THE LIMITATION OR EXCLUSION OF LIABILITY FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THE BELOW LIMITATION OR EXCLUSION MAY NOT APPLY TO YOU. TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW AND REGARDLESS OF WHETHER ANY REMEDY SET FORTH HEREIN FAILS OF ITS ESSENTIAL PURPOSE, IN NO EVENT WILL SYMANTEC BE LIABLE TO YOU FOR ANY SPECIAL, CONSEQUENTIAL, INDIRECT, OR SIMILAR DAMAGES, INCLUDING ANY LOST PROFITS OR LOST DATA ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE EVEN IF SYMANTEC HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. IN NO CASE SHALL SYMANTEC'S LIABILITY EXCEED THE PURCHASE PRICE FOR THE SOFTWARE. The disclaimers and limitations set forth above will apply regardless of whether or not You accept the Software. 5. U.S. Government Restricted Rights: RESTRICTED RIGHTS LEGEND. All Symantec products and documentation are commercial in nature. The software and software documentation are "Commercial Items," as that term is defined in 48 C.F.R. section 2.101, consisting of "Commercial Computer Software" and "Commercial Computer Software Documentation," as such terms are defined in 48 C.F.R. section (a)(5) and 48 C.F.R. section (a)(1), and used in 48 C.F.R. section and 48 C.F.R. section , as applicable. Consistent with 48 C.F.R. section , 48 C.F.R. section , 48 C.F.R. section through , 48 C.F.R. section , and other relevant sections of the Code of Federal Regulations, as applicable, Symantec's computer software and computer software documentation are licensed to United States Government end users with only those rights as granted to all other end users, according to the terms and conditions contained in this license agreement. Manufacturer is Symantec Corporation, Stevens Creek Blvd., Cupertino, CA 95014, United States of America. 6. Export Regulation: Certain Symantec products are subject to export controls by the U.S. Department of Commerce (DOC), under the Export Administration Regulations (EAR) (see Violation of U.S. law is strictly prohibited. Licensee agrees to comply with the requirements of the EAR and all applicable international, national, state, regional and local laws, and regulations, including any applicable import and use restrictions. Symantec products are currently prohibited for export or re-export to Cuba, North Korea, Iran, Iraq, Libya, Syria and Sudan or to any country subject to applicable trade sanctions. Licensee agrees not to export, or re-export, directly or indirectly, any product to any country outlined in the EAR, nor to any person or entity on the DOC Denied Persons, Entities and Unverified Lists, the U.S. Department of State's Debarred List, or on the U.S. Department of Treasury's lists of Specially Designated Nationals, Specially Designated Narcotics Traffickers, or Specially Designated Terrorists. Furthermore, Licensee agrees not to export, or re-export, Symantec products to any military entity not approved under the EAR, or to any other entity for any military purpose, nor will it sell any Symantec product for use in connection with chemical, biological, or nuclear weapons or missiles capable of delivering such weapons.

8 7. General: If You are located in North America or Latin America, this Agreement will be governed by the laws of the State of California, United States of America. Otherwise, this Agreement will be governed by the laws of England and Wales. This Agreement and any related License Module is the entire agreement between You and Symantec relating to the Software and: (i) supersedes all prior or contemporaneous oral or written communications, proposals, and representations with respect to its subject matter; and (ii) prevails over any conflicting or additional terms of any quote, order, acknowledgment, or similar communications between the parties. This Agreement shall terminate upon Your breach of any term contained herein and You shall cease use of and destroy all copies of the Software. The disclaimers of warranties and damages and limitations on liability shall survive termination. Software and documentation is delivered Ex Works California, U.S.A. or Dublin, Ireland respectively (ICC INCOTERMS 2000). This Agreement may only be modified by a License Module that accompanies this license or by a written document that has been signed by both You and Symantec. Should You have any questions concerning this Agreement, or if You desire to contact Symantec for any reason, please write to: (i) Symantec Customer Service, 555 International Way, Springfield, OR 97477, U.S.A., (ii) Symantec Customer Service Center, PO BOX 5689, Dublin 15, Ireland, or (iii) Symantec Customer Service, 1 Julius Ave, North Ryde, NSW 2113, Australia. C. If the Software You have licensed is Symantec Client Security, this Software utilizes the Standard Template Library, a C++ library of container classes, algorithms, and iterators. Copyright (c) Silicon Graphics Computer Systems, Inc. Copyright (c) Hewlett-Packard Company. 8. Additional Uses and Restrictions: A. If the Software You have licensed is a specified Symantec AntiVirus for a corresponding third party product or platform, You may only use that specified Software with the corresponding product or platform. You may not allow any computer to access the Software other than a computer using the specified product or platform. In the event that You wish to use the Software with a certain product or platform for which there is no specified Software, You may use Symantec Scan Engine. B. If the Software you have licensed is Symantec AntiVirus or Symantec Scan Engine utilizing Web Server optional licensing as set forth in the License Module, the following additional use(s) and restriction(s) apply: i)you may use the Software only with files that are received from third parties through a web server; ii)you may use the Software only with files received from less than 10,000 unique third parties per month; and iii)you may not charge or assess a fee for use of the Software for Your internal business.

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11 Contents Chapter 1 Chapter 2 Getting started About Symantec Scan Engine About the software developer s guide What s new Integrating with Symantec Scan Engine About ICAP About the API About other protocols About licensing Considerations for implementation Deciding how to implement scanning Maximizing performance About automatic load balancing Where to start Configuring Symantec Scan Engine for custom integrations Considerations for custom integration Configuring the scan engine Changing the ICAP response Chapter 3 Constructing clients using ICAP 1.0 How ICAP works About ICAP messages About ICAP requests About ICAP methods About ICAP services About ICAP responses About encapsulated messages Finding more information on ICAP About the scanning process About scanning URLs About sending files for scanning... 36

12 12 Contents Determining which services are supported (OPTIONS) Querying antivirus-only services Querying content-filtering services Querying antivirus and content-filtering services OPTIONS examples Scanning HTTP requests (REQMOD) REQMOD examples Scanning HTTP responses (RESPMOD) RESPMOD examples Scanning non-http data (RESPMOD and FILEMOD) About network scanning (RESPMOD) Local file scanning (FILEMOD) Chapter 4 Appendix A Constructing clients using the antivirus client-side API library General procedure for scanning Compiling and linking Compiling on Windows 2000 Server/Advanced Server Solaris Red Hat Linux Exceptions and error handling API functions File-based scanning Stream-based scanning ScanClientStartUp ScanClientScanFile ScanResultGetNumProblems ScanResultGetProblem SC_DECODE_DISPOSITION ScanResultsFree ScanClientShutDown ScanClientStreamStart ScanClientStreamSendBytes ScanClientStreamFinish ScanClientStreamAbort Using the antivirus API About the sample code Sample code Index

13 Chapter 1 Getting started This chapter includes the following topics: About Symantec Scan Engine About the software developer s guide What s new Integrating with Symantec Scan Engine About licensing Considerations for implementation Where to start About Symantec Scan Engine Symantec Scan Engine, formerly marketed as Symantec AntiVirus Scan Engine, is a carrier-class, network-accessible, content-scanning engine. The scan engine provides content scanning capabilities to any application on an IP network, regardless of platform. The scan engine features all of the key content-scanning technologies that are available in the complete line of Symantec products. The scan engine is one of the most effective solutions available for protecting your network against a variety of undesirable content. For more information, see the Symantec Scan Engine Implementation Guide.

14 14 Getting started About the software developer s guide About the software developer s guide Software developers can use the information that is provided in the Symantec Scan Engine Software Developer s Guide to create client applications that let third-party applications integrate with Symantec Scan Engine for a variety of content scanning services. Client applications can communicate with the scan engine using one of several supported protocols. However, the only protocol that is supported in the software developer s guide is the Internet Content Adaptation Protocol (ICAP) version 1.0, as presented in RFC 3507 (April 2003). What s new If you have constructed your own ICAP 1.0 client for Symantec Scan Engine, you can take advantage of the following new features: New ICAP methods The scan engine provides the following new commands: REQMOD Lets you scan outgoing HTTP requests and POST transactions for viruses and content filtering violations FILEMOD Lets you perform local file scanning URL and subject-matter content-filtering scanning The scan engine provides additional services that let you filter Web content based on subject matter. The scan engine applies Uniform Resource Locator (URL) and Dynamic Document Review (DDR) filtering to restrict access to Web sites that contain objectionable content and to block objectionable content. Local file scanning You can configure the client to send a full path name rather than the actual file to the scan engine. For example, files to be scanned might be located on a drive that can be mounted over the network, such as a shared drive in Windows or a network file system (NFS) drive. If the client application and the scan engine have access to a shared directory, the client application can place the file in the shared directory and pass the full path to the scan engine. This lets the scan engine access the file directly. See Constructing clients using ICAP 1.0 on page 23.

15 Getting started Integrating with Symantec Scan Engine 15 Integrating with Symantec Scan Engine Software developers can create client applications (connectors) that let thirdparty applications integrate with Symantec Scan Engine for content scanning services using ICAP as the communication protocol. You can create a custom integration using any of the following methods: Use the basic client-side antivirus application program interface (API) C library. If you plan to integrate antivirus scanning only, you can use the basic antivirus API. URL filtering is not available using the antivirus API. The antivirus API includes 12 libraries which includes static and dynamic libraries for each supported platform. The API library consists of 10 functions that provide scanning and repair services to client applications. See Using the antivirus API on page 85. Construct your own ICAP 1.0 client for the scan engine. If you construct your own ICAP client, you can specify whether to perform antivirus scanning and URL filtering for outgoing and incoming requests. See Constructing clients using ICAP 1.0 on page 23. About ICAP About the API ICAP is a lightweight protocol that was originally created to execute a remote procedure call on HTTP messages. ICAP is part of an evolving architecture that lets corporations, data communication companies, and Internet service providers (ISPs) dynamically scan, change, and augment data as it flows through ICAP servers. The protocol lets ICAP clients pass data to ICAP servers for adaptation (some type of transformation or other processing, such as virus or URL filtering). The server executes its transformation service on the data and responds to the client, possibly with modified content. In a typical integration for processing HTTP traffic, a caching proxy server retrieves the requested information from the Web. At the same time, it caches the information (stores a copy on disk) and, where possible, serves multiple requests for the same Web content from the cache. A caching proxy server can use ICAP to communicate with Symantec Scan Engine and request that content that is retrieved from the Web be scanned and repaired, if necessary. You can use the client-side API C library to configure an application to pass files to Symantec Scan Engine for scanning. The API includes 12 libraries, which includes static and dynamic libraries for each supported platform. The API

16 16 Getting started About licensing library consists of 10 functions that provide scanning and repair services to client applications. The scan engine API C library is available for the following platforms: Red Hat Linux 7.2 and later (using either gcc 2.95 or 3.2) Solaris 7 and later (using either gcc 2.95 or 3.2) Windows 2000 Server/Advanced Server (using either Microsoft Visual Studio 6 or 7) A C header file is included. See Configuring Symantec Scan Engine for custom integrations on page 19. About other protocols About licensing Symantec Scan Engine includes its own native protocol. However, this protocol is no longer supported in the software developer s kit. Symantec Scan Engine also supports Remote Procedure Call (RPC) 1.0 and 1.1 for Network Appliance (NetApp) Filer. This protocol is a proprietary implementation and is not documented by Symantec. Key features for Symantec Scan Engine are activated by license. After you install the scan engine, you install licenses through the scan engine administrative interface. The content-scanning features, including antivirus and URL filtering, are activated by product licenses. Subscription licenses let you obtain updates to virus definitions or URL filtering content updates. When a license expires, a new license must be installed. When no product license is installed, the scan engine is not operational. After you install a product license, you can access the relevant portions of the administrative interface, and the scan engine is operational. For example, if you activate a product license for antivirus scanning only (with no URL filtering), you are not able to access those portions of the administrative interface that relate to URL filtering. When no subscription license is installed or a subscription license expires, the scan engine is operational, but updates are not permitted. New virus definitions updates are not downloaded to keep protection current, and URL-filtering updates to the URL lists and DDR dictionaries are not permitted. For more information about licensing, see the Symantec Scan Engine Implementation Guide.

17 Getting started Considerations for implementation 17 Considerations for implementation Symantec Scan Engine can be easily implemented in an existing infrastructure. The scan engine runs on Sun Solaris, Red Hat Linux, SuSE Linux, and Windows 2000 Server/Advanced Server platforms. You can run the scan engine on the same computer or a different computer than the client application. Deciding how to implement scanning You can create a custom integration in one of the following ways using ICAP: Use the basic client-side antivirus application program interface (API) C library. If you plan to integrate antivirus scanning only, you can use the basic antivirus API. URL filtering is not available using the antivirus API. The antivirus API includes 12 libraries, which includes static and dynamic libraries for each supported platform. The API library consists of 10 functions that provide scanning and repair services to client applications. See Using the antivirus API on page 85. Construct your own ICAP 1.0 client for the scan engine. If you construct your own ICAP client, you can specify whether to perform antivirus scanning and URL filtering for outgoing and incoming requests. See Constructing clients using ICAP 1.0 on page 23. Maximizing performance The scan engine API supports both file-based and stream-based scanning. See File-based scanning on page 67. See Stream-based scanning on page 67. In a typical configuration, files are passed to Symantec Scan Engine through a socket over the network because the scan engine is running on a separate computer. Depending on the network setup, client applications (applications that are configured to pass files to the scan engine for scanning) can pass a full path rather than the actual file to the scan engine for improved performance. For example, files to be scanned may be located on a drive that can be mounted over the network, such as a shared drive in Windows or a network file system (NFS) drive. If the client application and the scan engine have access to a shared directory, the client application can place the file in the shared directory and pass the full path to the scan engine, which can access the file directly.

18 18 Getting started Where to start For cases in which the client application is running on the same computer as the scan engine, the client application can pass the file name to the scan engine, and the scan engine can open the file and scan it in place on the computer. See Local file scanning (FILEMOD) on page 59. About automatic load balancing Where to start The Symantec Scan Engine API provides scheduling across any number of computers that are running the scan engine. Client applications that pass files to the scan engine benefit from load-balanced virus scanning without any additional effort. When multiple scan engines are used, the API determines the appropriate scan engine to receive the next file to be scanned, based on the scheduling algorithm. If a scan engine is unreachable or stops responding during a scan, another scan engine is called and the faulty scan engine is taken out of rotation for a period of time (30 seconds is the default). If all of the scan engines are out of rotation, the faulty scan engines are called again. The API does not stop trying to contact the scan engines unless five engines do not respond or it appears that a file that is being scanned might have caused more than one engine to stop responding. Configuring client applications to use ICAP 1.0 to pass files to the scan engine for scanning involves the following process: Become familiar with the design and features of the software. In addition to this guide, see the Symantec Scan Engine Implementation Guide. Decide how to deploy the scan engine to meet your specific requirements. See Considerations for custom integration on page 19. Install and configure the scan engine to use ICAP as the communication protocol. For more information, see the Symantec Scan Engine Implementation Guide. Install the API libraries. See About the API on page 15. Configure the client applications that will send files to the scan engine for scanning. See Constructing clients using ICAP 1.0 on page 23. See Constructing clients using the antivirus client-side API library on page 63.

19 Chapter 2 Configuring Symantec Scan Engine for custom integrations This chapter includes the following topics: Considerations for custom integration Configuring the scan engine Changing the ICAP response Considerations for custom integration Symantec Scan Engine is designed to be easily integrated into any environment to provide content scanning for any application. Client applications are configured to pass files to the scan engine, which performs the required functions and returns the request with the necessary changes. The scan engine supports custom integrations in which the software developer creates a client application (connector) to provide content scanning services for a third-party application. The client application communicates with the scan engine using ICAP 1.0. You must configure the scan engine to support the custom integration. This includes the following tasks: Selecting ICAP as the communication protocol Configuring ICAP-specific options Configuring the scanning parameters

20 20 Configuring Symantec Scan Engine for custom integrations Configuring the scan engine You must decide how to configure the client application and the scan engine to ensure that scanning is handled appropriately. This decision can depend on the capabilities of the third-party application. For example, for antivirus scanning, the client application can decide which file types to scan and pass only the appropriate files to the scan engine. In other cases, you can configure the client application to pass all files to the scan engine, and then configure the scan engine to scan those file types that are likely to contain viruses. You must configure the client application to communicate with the scan engine and to handle the results that are returned from the scan engine. How the application is configured to handle the results that are returned from the scan engine can also depend on the capabilities of the third-party application, which includes, but is not limited to, the following: Blocking access to infected files or files that violate other configured policies Quarantining unrepairable files For example, for content scanning, the scan engine returns only the lookup results when you use audit mode. The client application applies the blocking policy based on the results. You can obtain information about configuring the client application to work with the scan engine in audit mode by contacting Symantec Service and Support. Configuring the scan engine Table 2-1 describes the minimum settings that you must configure for Symantec Scan Engine to perform scanning services. For more information about how to configure these options, see the Symantec Scan Engine Implementation Guide. Table 2-1 Setting Select the ICAP protocol and configure protocol options Symantec Scan Engine configuration options Description You must configure Symantec Scan Engine to use ICAP to communicate with clients that are running the proprietary version 1.0 of ICAP (RFC 3507, April 2003). Any appropriate client can use ICAP to communicate with the scan engine to request scanning and repairing of files. You can configure multiple client applications that use different versions of ICAP to pass files to a single scan engine. If you select ICAP as the protocol to be used by the scan engine, you must configure several ICAP-specific options. You must also configure the ICAP client to work with the scan engine.

21 Configuring Symantec Scan Engine for custom integrations Changing the ICAP response 21 Table 2-1 Setting Symantec Scan Engine configuration options Description Configure antivirus settings Specify processing limits Configure content filtering settings You can configure certain aspects of antivirus scanning, including the following options: Adjusting Bloodhound sensitivity Specifying file types to scan Establishing a mail filter policy You can impose restrictions on the amount of resources that are used to handle individual files. These processing limits let you manage resources and protect your network against denial-ofservice attacks. You can configure content-filtering settings, which includes the following options: Specifying content categories to deny Specifying URLs to allow Auditing URL sites rather than block access Changing the ICAP response In its default configuration, when ICAP is the communication protocol, Symantec Scan Engine sends a 201 Created response in the following scenarios: A virus was detected, but the file could not be repaired. A virus was detected and the scan engine is configured for scan-only mode. If a virus is detected and the file cannot be repaired or the scan engine is configured for scan-only mode, the scan engine includes a replacement file in the body of the response message. The replacement file is configurable through the scan engine administrative interface. The message informs users that access to a file is being denied because it contains a virus or content violation. The scan engine default behavior deviates from the ICAP 1.0 standard, which does not support automatically sending a replacement file. In the ICAP 1.0 standard, this type of context-sensitive behavior is performed by the client rather than by the scan engine. If your client application closely follows the ICAP 1.0 standard, you might need to change the scan engine default ICAP response setting to receive an ICAP 403 response instead of a replacement file. The scan engine sends a 403 response if the file is denied based on the scan engine policy setting. If the file is acceptable, the scan engine returns a 200 OK response. You should change the default ICAP

22 22 Configuring Symantec Scan Engine for custom integrations Changing the ICAP response response setting only if you are sure that the client application supports this behavior. To make this change, you must edit the configuration.xml file using the XML modifier tool. The XML modifier tool is provided on the Symantec Scan Engine product CD. This tool is automatically installed when you install the product. For more information, see the Symantec Scan Engine Implementation Guide. To change the ICAP response 1 In the XML modifier tool, at the command line, type the following command: java -jar xmlmodifier.jar 2 Type the following XPath: /configuration/protocol/icap/icapresponse/@value is one of the following: 0 Send an ICAP 403 response 1 Send a replacement file. This is the default setting. 3 Stop and restart the scan engine.

23 Chapter 3 Constructing clients using ICAP 1.0 This chapter includes the following topics: How ICAP works About the scanning process Determining which services are supported (OPTIONS) Scanning HTTP requests (REQMOD) Scanning HTTP responses (RESPMOD) Scanning non-http data (RESPMOD and FILEMOD) How ICAP works The Internet Content Adaptation Protocol (ICAP) is a request/response-based protocol that lets ICAP clients pass messages to ICAP servers for processing or adaptation. The client initiates the session by sending request messages over a TCP/IP connection to a passively waiting ICAP server on a designated port. (Port 1344 is the default ICAP port.) The server then does the following: Runs the service that was requested, such as antivirus scanning Performs any transformations that are necessary, such as repairing an infected file Sends a response back to the client with any modified data A single transport can be used for multiple request/response pairs. Requests are matched with responses by allowing only one outstanding request on a connection at a time. Multiple connections can be used.

24 24 Constructing clients using ICAP 1.0 How ICAP works About ICAP messages ICAP clients and servers communicate through messages, which are similar in format to HTTP. ICAP messages consist of client requests and server responses. All ICAP messages consist of a start line, which includes a client request or server response (depending on the type of message), header fields, and the message body. A blank line precedes the message body to distinguish the headers from the message body. Multiple HTTP message sections can be encapsulated in a single ICAP message for vectoring of requests, responses, and request/response pairs on an ICAP server. Encapsulated messages must include an encapsulated header, which offsets the start of each encapsulated section from the start of the message body. See About encapsulated messages on page 33. Although request and response messages have unique headers, some headers are common to both requests and responses. Table 3-1 lists the general request/response headers that Symantec Scan Engine uses. Table 3-1 Header Connection Date General request/response headers Description Specifies options that the message sender wants to use only for that connection and not for proxies over other connections. For example: Connection: close Provides the date and time that the message was created, using standard HTTP date and time format. For example: Date: Tue, 5 July :29:31 GMT

25 Constructing clients using ICAP 1.0 How ICAP works 25 About ICAP requests All ICAP client requests must start with a request line that includes the following components: Method Uniform Resource Identifier (URI) ICAP version ICAP command or operation to perform (for example, REQMOD) Complete host name of the ICAP server and the path of the resource that is being requested Version string for the current version of ICAP using the format ICAP/version number (for example ICAP/1.0) The URI consists of the following components: ICAP_URI = Scheme ":" Net_Path [ "?" Query ] Scheme = "icap" Net_Path = "//" Authority [ Abs_Path ] Authority = [ userinfo "@" ] host [ ":" port ] The request line specifies the ICAP resource that is being requested. Header fields follow with information, such as cache control and preview size. The header fields end with a blank line followed by the message body. The message body contains the encapsulated HTTP message sections that are being sent for scanning and modification. Table 3-2 lists the specific request headers that are allowed in ICAP requests. Table 3-2 Header Allow From Host Request headers Description Lists the methods that the resource supports. For example, a client request can include an Allow: 204 header, which indicates that it will allow the server to reply to the message with a 204 No Content response if the file does not need modification. The client must buffer the message. Provides the Internet address for the user who is sending the client request. The address should use the standard HTTP mailbox format. For example: From: username@symantecdomain.com Specifies the host name and port number of the resource being requested.

26 26 Constructing clients using ICAP 1.0 How ICAP works Table 3-2 Header Referer User-Agent Preview Encapsulated Request headers Description Specifies the path that the client followed to obtain the URI. This optional header lets the server generate lists of backwards navigation links to resources and trace invalid links. Identifies the software program that is used by the client that originated the request. This information is used for statistical purposes, to trace protocol violations, and to tailor responses to the software capabilities. (ICAP-specific header) Lets the client send a portion of a file to the scan engine for scanning. The client uses this header to specify the amount of data, in bytes, that will be sent for preview. Lists offsets of the start of each encapsulated section from the start of the message body. Opt-body=0 indicates filtering categories will be returned. See About encapsulated messages on page 33. X-Filepath Specifies the full file path to a local file. About ICAP methods Symantec Scan Engine supports the following ICAP methods: OPTIONS (options mode) Lets the client obtain information from an ICAP server about available services. See Determining which services are supported (OPTIONS) on page 38. REQMOD (request modification mode) Lets the client send URLs to the scan engine for scanning services. In request modification mode, the ICAP client receives a request from a user, usually a Webbrowser. The client passes the data to the scan engine for evaluation and processing. See Scanning HTTP requests (REQMOD) on page 50.

27 Constructing clients using ICAP 1.0 How ICAP works 27 RESPMOD (response modification mode) Lets the client send files to the scan engine for scanning services. In response modification mode, the ICAP client receives a data response from an origin server. The client passes the data to the scan engine for evaluation and post-processing. See Scanning HTTP responses (RESPMOD) on page 54. FILEMOD (file modification mode) Lets the client pass a file name and path to the scan engine so that the scan engine can scan the file in place (rather than streaming the file to the scan engine for scanning). Note: File modification mode deviates from the ICAP 1.0 specification that is presented in RFC 3507 (April 2003). See Scanning non-http data (RESPMOD and FILEMOD) on page 58. About ICAP services Symantec Scan Engine supports antivirus and URL content-filtering scanning. You must include an ICAP service name in the ICAP URI to specify the type of scanning that you want the scan engine to perform. Previous versions of Symantec AntiVirus Scan Engine used a different ICAP service naming convention. These services are supported for backward compatibility. New clients should use the new services, which include enhancements over the previous services. Table 3-3 describes the ICAP services, descriptions, and the supported methods. Table 3-3 ICAP services ICAP service name Description Method options Legacy or New service AVSCANREQ Lets you apply antivirus scanning to client request data (compatible with Symantec AntiVirus Scan Engine) REQMOD Legacy AVSCANRESP Lets you apply antivirus scanning to client response data (compatible with Symantec AntiVirus Scan Engine) RESPMOD, FILEMOD Legacy AVSCAN Lets you apply antivirus scanning to client response data RESPMOD, FILEMOD Legacy

28 28 Constructing clients using ICAP 1.0 How ICAP works Table 3-3 ICAP services ICAP service name Description Method options Legacy or New service SYMCScanReq-AV HTTP request is provided to the scan engine for antivirus scanning REQMOD New SYMCScanReq-AV-URL HTTP request is provided to the scan engine for antivirus and URL-filtering scanning REQMOD New SYMCScanReq-URL HTTP request is provided to the scan engine for URL-filtering scanning REQMOD New SYMCScanResp-AV HTTP response is provided to the scan engine for antivirus scanning RESPMOD, FILEMOD New SYMCScanResp-AV-DDR HTTP response is provided to the scan engine for antivirus and URL-filtering scanning RESPMOD, FILEMOD New SYMCScanResp-DDR HTTP response is provided to the scan engine for DDR scanning RESPMOD, FILEMOD New The ICAP service argument is used to specify the antivirus scanning policy. The action=repairpolicy argument can override the antivirus scanning repair policy for the scan engine. For services that do not perform antivirus scanning, SYMCScanReq-URL and SYMCScanResp-DDR, the argument is ignored. The ICAP service argument is as follows: action=repairpolicy where repair policy consists of one of the following: scanrepairdelete scanrepair scandelete scan You can append the argument to the service name by adding a question mark and then the argument. For example: SYMCSCANRESP-AV?action=scanrepairdelete