Sanewall is a firewall builder for Linux that uses an elegant language abstracted to just the right level. This makes it powerful and easy to use, audit, and understand. It allows you to create very readable configurations even for complex stateful firewalls. Sanewall can be used for almost any purpose, including control of any number of internal/external/virtual interfaces, control of any combination of routed traffic, setting up DMZ routers and servers, all kinds of NAT, providing strong protection (flooding, spoofing, etc.), transparent caches, source MAC verification, blacklists, and whitelists. Newer versions abstract the differences between IPv4 and IPv6, allowing you to define a common set of rules for both, while permitting specific rules for each as you need. Sanewall is a fork of FireHOL and can make use of existing FireHOL configurations.
txtorcon is a Twisted-based asynchronous Tor control protocol implementation. Twisted is an event-driven networking engine written in Python, and Tor is an onion-routing network designed to improve people’s privacy and security on the Internet. It includes unit-tests with 96%+ coverage, multiple examples, and documentation. There are abstractions to track Tor configuration and state (circuits, streams), launch private instances, support Hidden Service, and more.
phpSecurePages is a PHP module to secure pages with a login name and password. It can handle multiple user groups (each with their own viewing rights), store data in a MySQL database or a configuration file, and be used to identify your Web site viewers. It also has multiple language support and optional IP-based access restrictions.
Hiawatha is a secure and advanced Web server for Unix. It has been written with security as its main goal. It features advanced access control, prevention of SQL injection and cross-site scripting, banning of clients who try such exploits, the ability to run CGIs under any UID/GID you want, and many other features. These features make Hiawatha an interesting Web server for those who need more security than what the other available Web servers are offering. Hiawatha is also fast and easy to configure.
Shishi is a (still incomplete) implementation of Kerberos 5, which can be used to authenticate users in distributed systems. It contains a library that can be used by application developers, and a command line utility for users. Shishi supports Kerberos authenticated telnet client/server, IMAP client/server (via GSSAPI), SSH client/server (via GSSAPI), rsh/rlogin client, and a PAM module for host security.
Tor is a network of virtual tunnels that allows people and groups to improve their privacy and security on the Internet. It also enables software developers to create new communication tools with built-in privacy features. It provides the foundation for a range of applications that allow organizations and individuals to share information over public networks without compromising their privacy. Individuals can use it to keep remote Websites from tracking them and their family members. They can also use it to connect to resources such as news sites or instant messaging services that are blocked by their local Internet service providers (ISPs).