Cisco PIX 525 Spezifikationen PDF herunterladen (Seite 286)

17-6

Cisco Security Appliance Command Line Configuration Guide

OL-6721-01

Chapter 17 Applying Filtering Services

Filtering with an External Server

Replace if_name with the name of the security appliance interface that is connected to the filtering server

(the default is inside). Replace local_ip with the IP address of the filtering server. Replace seconds with

the number of seconds the security appliance should keep trying to connect to the filtering server.

Note The default port is 4005. This is the default port used by the N2H2 server to communicate to the security

appliance via TCP or UDP. For information on changing the default port, please refer to the Filtering by

N2H2 Administrator's Guide.

For example, to identify a single Websense filtering server, enter the following command:

hostname(config)# url-server (perimeter) host 10.0.1.1

This identifies a Websense filtering server with the IP address 10.0.1.1 on a perimeter interface of the

security appliance.

To identify redundant N2H2 Sentian servers, enter the following commands:

hostname(config)# url-server (perimeter) vendor n2h2 host 10.0.1.1

hostname(config)# url-server (perimeter) vendor n2h2 host 10.0.1.2

This identifies two Sentian filtering servers, both on a perimeter interface of the security appliance.

Buffering the Content Server Response

When a user issues a request to connect to a content server, the security appliance sends the request to

the content server and to the filtering server at the same time. If the filtering server does not respond

before the content server, the server response is dropped. This delays the web server response from the

point of view of the web client because the client must reissue the request.

By enabling the HTTP response buffer, replies from web content servers are buffered and the responses

are forwarded to the requesting client if the filtering server allows the connection. This prevents the

delay that might otherwise occur.

To configure buffering for responses to HTTP or FTP requests, perform the following steps:

Step 1 To enable buffering of responses for HTTP or FTP requests that are pending a response from the filtering

server, enter the following command:

hostname(config)# url-block block

block-buffer-limit

Replace block-buffer-limit with the maximum number of blocks that will be buffered.

Note Buffering URLs longer than 1159 bytes is only supported for the Websense filtering server.

Step 2 To configure the maximum memory available for buffering pending URLs (and for buffering long URLs

with Websense), enter the following command:

hostname(config)# url-block url-mempool

memory-pool-size

Replace memory-pool-size with a value from 2 to 10240 for a maximum memory allocation of 2 KB to

10 MB.

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Cisco PIX 525 Spezifikationen Seite 286