AMaViS (A Mail Virus Scanner) scans e-mail attachments for viruses using third-party virus scanners available for UNIX environments. It resides on a UNIX (Linux) machine and looks through the attached files arriving via e-mail, generates reports when a virus is found and sets the delivery on hold.
ClarkConnect is a powerful yet easy-to-use server/gateway software solution designed for the small/medium-sized organization. The software provides all the necessary server tools to run an organization: email, antivirus, antispam, file sharing, groupware, VPN, firewall, intrusion detection/prevention, content filtering, bandwidth management, multi-WAN and more.
Dante is a free implementation of the proxy protocols SOCKS version 4 and SOCKS version 5 (RFC 1928). It can be used as a firewall between networks, controlling outgoing traffic. The package consists of two parts: a socks server and a proxy client that supports socks, HTTP proxies, and UPnP. RFC 1961 (GSSAPI) is supported in both the client and the server. Commercial support is available.
DeleGate is a multi-purpose application level gateway or proxy server that mediates communication of various protocols, applying cache and conversion for mediated data, controlling access from clients, and routing toward servers. It translates protocols between clients and servers, converting between IPv4 and IPv6, applying SSL (TLS) to arbitrary protocols, merging several servers into a single server view with aliasing and filtering. It can be used as a simple origin server for some protocols (HTTP, FTP, and NNTP).
The Falcon Project (Free Application-Level CONnection kit) is an open firewall project with the intention of developing a free, secure and OS-independent firewall system. Falcon consists of three major modules: Falcons's own proxies (written in Perl); 3rd-party proxies (squid / qmail / BIND8), each modified for chroot environment; and general concepts for OS hardening, chrooting etc.