Best Practices for Securing SNMP for Symantec Web Gateway (SWG)

Products

• Web Gateway

Issue/Introduction

You seek information on how to implement Simple Network Management Protocol (SNMP) as provided by Symantec Web Gateway (SWG).

Cause

Simple Network Management Protocol includes the snmpbulkget command. SWG must respond to this command to comply with RFC specifications. However, responding as the RFC's require takes CPU time at the SWG appliance and network bandwidth at the intervening devices. For these reasons, and to restrict the information available to only your designated administration staff, Symantec recommends restricting SNMP protocol access for SWG Appliance.

Resolution

1. Restrict SNMP management access using the management list.
2. Use a non-default community string.
3. If the SNMP facility you use supports SNMPv3, specify SNMPv3 users.

To restrict SNMP management access using the management list

1. Within the web interface of SWG Appliance, click Administration> Configuration
2. Click SNMP
3. Click Add a SNMP Manager
4. In the field that appears, type either an IP address or a CIDR address.
5. Click Save

To use a non-default community string

1. Within the web interface of SWG Appliance, click Administration> Configuration
2. Click SNMP
3. In the text field labelled "SNMP Community String", delete the word "public", and type a community string that is unique to your organization.
4. Click Save

To specify a user for SNMPv3

1. Within the web interface of SWG Appliance, click Administration> Configuration
2. Click SNMP
3. In the text field labelled "Username", specify a username
4. In the text field labelled "Password (8 characters minimal)", specify a password with a minimum of 8 characters.
5. In the "Authentication" dropdown box, select either "MD5" or "SHA".
6. In the text field labelled "Secret Key (8 characters minimal)", specify a secret key at least 8 characters in length.
7. In the "Encryption" dropdown box, select either "DES" or "AES".
8. Click Save.

References

The Administrative Guide and other Web Gateway documentation can be found here:
http://www.symantec.com/business/support/documentation.jsp?language=english&view=manuals&pid=58161


The following RFC references may be helpful in understanding SNMP design and implementation:
Title: Version 2 of the Protocol Operations for the Simple Network Management Protocol (SNMP)
URL: http://www.rfc-editor.org/rfc/rfc3416.txt

Title: User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)
URL: http://www.rfc-editor.org/rfc/rfc3414.txt