You can configure url filtering on the ASA so that the request are first sent to the filtering server before it can be processed. The ASA supports N2H2 or websense for filtering. This can be configured as follows:
I am assuming that the ip address of the filtering server is 10.0.1.1 and it is located on the inside.
Using N2H2, the following example filters all outbound HTTP connections except those from the 10.0.2.20 host:
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...