Cisco PIX 525 Dokumentacja Pobierz pdf (Strona 151)

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Cisco PIX Firewall and VPN Configuration Guide

78-15033-01

Chapter 3 Controlling Network Access and Use

Filtering Outbound Connections

Step 3 (Optional) Enable buffering of HTTP replies for URLs that are pending a response from the filtering

server by entering the following command:

url-block block block-buffer-limit

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

Step 4 (Optional) Configure the maximum memory available for buffering pending URLs (and for buffering

long URLs with Websense) with the following command:

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.

Step 5 (Optional for Websense only) Configure the maximum size of a single URL with the following

command:

url-block url-size long-url-size

Replace long-url-size with a value from 2 to 4 for a maximum URL size of 2 KB to 4 KB. The default

value is 2.

Step 6 (Optional) To handle URLs that are longer than the maximum available buffer size, enter the filter

command in the following form:

filter url [longurl-truncate | longurl-deny | cgi-truncate]

Use the longurl-truncate command to send only the host name or IP address portion of the URL for

evaluation to the filtering server when the URL is longer than the maximum length permitted.

Use the longurl-deny option to deny outbound traffic if the URL is longer than the maximum permitted

(1159 for N2H2 or configurable up to 4 KB for Websense).

Use the cgi-truncate option to send a CGI script as the URL.

Step 7 (Optional) To display memory usage, enter the following commands:

show chunk

show memory

Step 8 (Optional) Use the url-cache command if needed to improve throughput, as follows:

url-cache dst | src_dst size

Note This command does not update Websense logs, which may affect Websense accounting reports.

Accumulate Websense run logs before using the url-cache command.

Replace size with a value for the cache size within the range 1 to 128 (KB).

Use the dst keyword to cache entries based on the URL destination address. Select this mode if all users

share the same URL filtering policy on the Websense server.

Use the src_dst keyword to cache entries based on both the source address initiating the URL request as

well as the URL destination address. Select this mode if users do not share the same URL filtering policy

on the Websense server.

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Cisco PIX 525 Dokumentacja Strona 151