Cisco ASA 5505 Configuration Manual page 718

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 and includes the
following topics:
•
•
•
•
•
•
Information About URL Filtering
You can apply filtering to connection requests originating from a more secure network to a less secure
network. Although you can use ACLs 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 adaptive security appliance performance by using a separate server running
one of the following Internet filtering products:
•
•
Note URL caching will only work if the version of the URL server software from the URL server vendor
supports it.
Although adaptive security appliance performance is less affected when using an external server, you
may notice longer access times to websites or FTP servers when the filtering server is remote from the
adaptive security appliance.
When filtering is enabled and a request for content is directed through the adaptive security appliance,
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 adaptive security appliance forwards the response from the content server to
the originating client. If the filtering server denies the connection, the adaptive security appliance drops
the response and sends a message or return code indicating that the connection was not successful.
If user authentication is enabled on the adaptive security appliance, then the adaptive security appliance
also sends the username to the filtering server. The filtering server can use user-specific filtering settings
or provide enhanced reporting about usage.
Cisco ASA 5500 Series Configuration Guide using ASDM
34-2
Information About URL Filtering, page 34-2
Licensing Requirements for URL Filtering, page 34-3
Guidelines and Limitations for URL Filtering, page 34-3
Identifying the Filtering Server, page 34-3
Configuring Additional URL Filtering Settings, page 34-4
Feature History for URL Filtering, page 34-12
Websense Enterprise for filtering HTTP, HTTPS, and FTP.
Secure Computing SmartFilter (formerly N2H2) for filtering HTTP, HTTPS, FTP, and long URL
filtering.
Chapter 34 Configuring Filtering Services
OL-20339-01