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.
FrazierWall Linux is a single floppy distribution Linux firewall that is based on the Linux Router Project. It is designed for use with ethernet base internet connections (such as cable modems or xDSL lines). It allows you to share such a connection with several other computers on a LAN. It is easy to setup and maintain, and is available in a Linux configurable software version.
tircproxy is a full featured IRC proxy. It can proxy DCC CHAT, DCC SEND and other DCC requests transparently to the user, block common trojans (such as script.ini), hide the user's identity and more. It can be used with the Linux kernel or IPF transparent proxy features to transparently proxy IRC sessions.
'NTLM Authorization Proxy Server' (APS) is a proxy software that allows you to authenticate via an MS Proxy Server using the proprietary NTLM protocol. APS has the ability to behave as a standalone proxy server and authenticate HTTP clients at Web servers using the NTLM protocol. It can change arbitrary values in your client's request headers so that those requests will look like they were created by MS IE. It is written in Python 1.5.2.
Actim allows you to send and retrieve files, and to call command line programs on a target machine via emails. The application can handle both synchronous and asynchronous requests with basic security features. It has both command line and graphical user interfaces. This can be useful if, for example, your home PC does not have any access to your office workstation which is behind the company firewall.
MailScanner is an email virus scanner, vulnerability protector, and spam tagger. It supports the Postfix, Sendmail, Exim, Qmail, and ZMailer MTAs, and the Sophos, McAfee, F-Prot, F-Secure, CommandAV, InoculateIT, Inoculan, eTrust, Kaspersky, Nod32, AntiVir, BitDefender, RAV, Panda, DrWeb, ClamAV, and other anti-virus scanners. It uses SpamAssassin for highly successful spam identification, and is designed to handle denial of service attacks. It will detect password-protected zip files and apply filename checking to their contents. It is very easy to install, requires no changes at all to your sendmail.cf file, is designed to be lightweight, and won't grind your mail system to a halt with its load. It can be integrated into any email system, regardless of the software in use.
DummyIdentd Server Daemon is a Perl program that accepts identd requests (port 113), and responds with a valid response, but giving out no useful information. It is written in Perl, and is suitable for running on company gateways/firewalls to enable your users to access services such as IRC, which require identd.
The IP Masquerade HOWTO is the document that contains instructions on understanding, configuring, and troubleshooting NAT or Network Address Translation for Linux. It covers topics such as IPTABLES, PORTFW, IPCHAINS, IPFWADM, stronger packet firewalls, multiple network segments, and configuring many client operating systems. It also has an extensive FAQ and troubleshooting section.