User manual BARRACUDA SPAM VIRUS FIREWALL 4.X ADMINISTRATOR GUIDE

[. . . ] Firmware Version 4. x Barracuda Spam & Virus Firewall Administrator's Guide Barracuda Networks Inc. Winchester Blvd Campbell, CA 95008 http://www. barracuda. com Copyright Notice Copyright 2004-2009, Barracuda Networks www. barracuda. com v4. x-090623-06-1119 All rights reserved. Information in this document is subject to change without notice. Trademarks Barracuda Spam & Virus Firewall is a trademark of Barracuda Networks. All other brand and product names mentioned in this document are registered trademarks or trademarks of their respective holders. 2 Barracuda Spam & Virus Firewall Administrator's Guide Contents Chapter 1 ­ Introduction . [. . . ] Information that you may want to add to an NDR includes the contact information of the Barracuda Spam & Virus Firewall administrator so that internal users know who to contact if they have questions about a blocked message. The ADVANCED > Bounce/NDR Messages page allows for modifying the information in an NDR and for selecting the default language to use in the message. Reducing Backscatter By default, your Barracuda Spam & Virus Firewall is configured to NOT send an NDR to a sender when the Barracuda Spam & Virus Firewall blocks their email. You may want to enable NDRs to alert legitimate senders that their message has not been delivered to the recipient. However, if the email came from an illegitimate source such as a spammer, then sending a bounce notification is not necessary. Additionally, many spammers spoof valid domains, and you don't want to send bounce messages to your domain if it is being spoofed. Sending bounce messages to illegitimate senders is known as "backscatter". Backscatter can increase the load on your Barracuda Spam & Virus Firewall and may generate a lot of email to fake addresses. Additionally your domain could end up on a real-time blacklist as a consequence. If your Barracuda Spam & Virus Firewall rarely blocks a legitimate email, consider turning off bounce notifications to reduce backscatter by setting the Send Bounce feature on the ADVANCED > Bounce/NDR Settings page to No. Advanced Configuration 71 Remote Administration Barracuda Networks provides a set of APIs for remote administration and configuration of the Barracuda Spam & Virus Firewall, firmware version 4. x. The APIs work through manipulation of variables inside of the system configuration database, and anything that can be declared in that database can be set or checked with the APIs. This includes most things that you can set by clicking the Save Changes button in the Barracuda Spam & Virus Firewall Web interface. For example, from the BASIC > Spam Checking page, you can set global Spam Scoring Limit values for the actions Block, Tag or Quarantine, then click the Save Changes button. The framework of the API provides for the programmer to get or set variables inside an XML-RPC request that correspond to field values in the configuration database in the Barracuda Spam & Virus Firewall. Some languages such as Perl, for example, provide wrappers for XML-RPC requests, providing an interface to form the request. To view the variables and current settings of the Barracuda Spam & Firewall configuration database, on the ADVANCED > Backup page, select System Configuration for Backup Type and click the Backup button. To prepare the Barracuda Spam & Virus Firewall for use with the APIs, you must first enter the IP addresses that are allowed to communicate with the APIs in the Allowed SNMP and API IP/Range field on the BASIC > Administration page, and you must create an API Password that will be included with all calls to the APIs. For more information on using the APIs, see the Barracuda Spam & Virus Firewall API Guide 4. x on the Barracuda Web site: http://www. barracuda. com/support. 72 Barracuda Spam & Virus Firewall Administrator's Guide Chapter 7 Managing Quarantine The Barracuda Spam & Virus Firewall provides a fully featured, robust quarantine function to apply at either a global level or at a per-user level, configurable for each domain managed by the appliance. This chapter covers some pros and cons of enabling quarantine and how and why to use global or peruser quarantine. How Quarantine Works. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Quarantine Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Global Quarantine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Per-User Quarantine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Managing Quarantine 73 How Quarantine Works After a message travels through the initial filtering layers of the Barracuda Spam & Virus Firewall, it is assigned a score based on the probability that it is spam. 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