Buffering The Content Server Response - Cisco FirePOWER ASA 5500 series Configuration Manual

Chapter 20 Applying Filtering Services
Filtering URLs and FTP Requests with an External Server
where <if_name> is the name of the security appliance interface connected to the filtering server (the
default is inside).
For the vendor {secure-computing | n2h2}, you can use 'secure-computing as a vendor string, however,
'n2h2' is acceptable for backward compatibility. When the configuration entries are generated,
'secure-computing' is saved as the vendor string.
The host <local_ip> is the IP address of the URL filtering server.
The port <number> is the Secure Computing SmartFilter server port number of the filtering server; the
security appliance also listens for UDP replies on this port.
The default port is 4005. This is the default port used by the Secure Computing SmartFilter server to
Note
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.
The timeout <seconds> is the number of seconds the security appliance should keep trying to connect
to the filtering server.
The connections <number> is the number of tries to attempt to make a connection between the host and
server.
For example, to identify a single Websense filtering server, enter the following command:
hostname(config)# url-server (perimeter) host 10.0.1.1 protocol TCP version 4
This identifies a Websense filtering server with the IP address 10.0.1.1 on a perimeter interface of the
security appliance.Version 4, which is enabled in this example, is recommended by Websense because it
supports caching.
To identify redundant Secure Computing SmartFilter 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 with the maximum number of HTTP responses that can be buffered while awaiting
responses from the url-server.
Cisco Security Appliance Command Line Configuration Guide
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