Filtering Urls And Ftp Requests With An External Server; Url Filtering Overview; Identifying The Filtering Server - Cisco 7604 Configuration Manual

Filtering URLs and FTP Requests with an External Server

Filtering URLs and FTP Requests with an External Server
This section describes how to filter URLs and FTP requests with an external server. This section includes
the following topics:
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URL Filtering Overview

You can apply filtering to connection requests originating from a more secure network to a less secure
network. Although you can use access lists to prevent outbound access to specific content servers,
managing usage this way is difficult because of the size and dynamic nature of the Internet. You can
simplify configuration and improve FWSM performance by using a separate server running one of the
following Internet filtering products:
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Although FWSM performance is less affected when using an external server, users may notice longer
access times to websites or FTP servers when the filtering server is remote from the FWSM.
When filtering is enabled and a request for content is directed through the FWSM, the request is sent to
the content server and to the filtering server at the same time. If the filtering server allows the connection,
the FWSM forwards the response from the content server to the originating client. If the filtering server
denies the connection, the FWSM drops the response and sends a message or return code indicating that
the connection was not successful.
If user authentication is enabled on the FWSM, then the FWSM also sends the username to the filtering
server. The filtering server can use username filtering settings or provide enhanced reporting regarding
usage.

Identifying the Filtering Server

You can identify up to four filtering servers per context. The FWSM uses the servers in order until a
server responds. You can only configure a single type of server (Websense or N2H2) in your
configuration.
You must add the filtering server before you can configure filtering for HTTP or HTTPS with the filter
Note
command. You must also remove all filtering command before you remove the filtering servers from the
configuration.
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
18-4
URL Filtering Overview, page 18-4
Identifying the Filtering Server, page 18-4
Buffering the Content Server Response, page 18-6
Caching Server Addresses, page 18-6
Filtering HTTP URLs, page 18-7
Filtering HTTPS URLs, page 18-8
Filtering FTP Requests, page 18-9
Websense Enterprise for filtering HTTP, HTTPS, FTP, and long URL filtering.
Secure Computing SmartFilter (formerly N2H2) for filtering HTTP, and HTTPS filtering.
Chapter 18 Applying Filtering Services
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