QuintoLabs Content Security is an ICAP server/URL rewriter that integrates with your Squid Proxy Server to provides rich content filtering functionality, sanitizing Internet traffic passing into internal enterprise networks. It may be used to block illegal or potentially malicious file downloads, remove annoying advertisements, prevent access to various categories of Web sites, and block resources with explicit content.
Cyan Secure Web Proxy Server is a carrier grade, high performance Internet filtering proxy server for Linux. It includes scalable (user/group/host) Web filter and virus scan utilities for blocking malicious applications at the gateway. It has an advanced URL database, authentication support (Active Directory, LDAP, NTLM), SSL Interception, easy deployment, and remote administration.