Cisco PIX 525 Especificaciones descargar pdf (Pagina 378)

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Cisco Security Appliance Command Line Configuration Guide

OL-6721-01

Chapter 21 Applying Application Layer Protocol Inspection

Managing SMTP and Extended SMTP Inspection

• For unknown commands, the security appliance changes all the characters in the packet to X. In this

case, the server generates an error code to the client. Because of the change in the packed, the TCP

checksum has to be recalculated or adjusted.

• TCP stream editing.

• Command pipelining.

Enabling and Configuring SMTP and Extended SMTP Application Inspection

To enable SMTP and extended SMTP inspection or change the default port used for receiving SMTP

traffic, perform the following steps:

Step 1 Name the traffic class by entering the following command in global configuration mode:

hostname(config)# class-map

class_map_name

Replace class_map_name with the name of the traffic class, for example:

hostname(config)# class-map smtp_port

When you enter the class-map command, the CLI enters the class map configuration mode, and the

prompt changes, as in the following example:

hostname(config-cmap)#

Step 2 In the class map configuration mode, define the match command, as in the following example:

hostname(config-cmap)# match port tcp eq 25

hostname(config-cmap)# exit

hostname(config)#

To assign a range of continuous ports, enter the range keyword, as in the following example:

hostname(config-cmap)# match port tcp range 2025-2030

To assign more than one non-contiguous port for SMTP inspection, enter the access-list command and

define an access control entry to match each port. Then enter the match command to associate the access

lists with the SMTP traffic class.

Step 3 Name the policy map by entering the following command:

hostname(config)# policy-map

policy_map_name

Replace policy_map_name with the name of the policy map, as in the following example:

hostname(config)# policy-map inbound_policy

The CLI enters the policy map configuration mode and the prompt changes accordingly, as follows:

hostname(config-pmap)#

Step 4 Specify the traffic class defined in Step 2 to be included in the policy map by entering the following

command:

hostname(config-pmap)# class

class_map_name

For example, the following command assigns the smtp_port traffic class to the current policy map.

hostname(config-pmap)# class smtp_port

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