conntrack-tools is a set of userspace tools for Linux that allow system administrators to interact with the Connection Tracking System, the module which provides stateful packet inspection for iptables. It includes the userspace daemon conntrackd and the commandline interface conntrack.
fireparse is an ADMLogger plugin that emails a report of all packets that have been logged by the kernel's packet filtering subsystem (iptables/netfilter or ipchains). The report includes source and destination ports, direction, logged packet count, matched rule, and fully resolved host names (if available). The email report can be formatted to plain text or a colored HTML table.
CIPE (Crypto IP Encapsulation) is an ongoing project to build encrypting IP routers. The protocol used is as lightweight as possible. It is designed for passing encrypted packets between prearranged routers in the form of UDP packets. This is not as flexible as IPSEC but it is enough for the original intended purpose: securely connecting subnets over an insecure transit network.
Gibraltar is a Debian GNU/Linux-based router/firewall distribution, fully workable from a bootable, live CD-ROM. Log files can be stored on a hard disk, and configuration data is stored on a USB mass storage media or a floppy disk and kept on a RAM disk during run-time. Due to its Debian base, a vast manifold of firewalling, routing, and proxy packages is available. It comes with an intuitive, easy to use Web administration interface and support, and is free to use for home users.
The Auditor security collection is a live-system based on KNOPPIX. It provides tools for analyzing the security of a system. It features a menu structure that reflects the stages of a security check: foot-printing, analysis, scanning, wireless, brute-forcing, cracking. In addition to about 300 security tools, the collection includes background information regarding standard configuration and passwords, truly extensive word lists, and more mundane productivity tools.
BBStatus is an IP accounting package and an SNMP and IP monitoring tool for Linux. It collects, summarizes, and displays the values from its database. It can be used for IP accounting (allows you to design various kinds of accounting filters), SNMP monitoring (collects data making SNMP requests), ICMP monitoring (stores and summarizes values like min, avg, max reply time, and packet loss), and client traffic filtering (using various types of filters). It also provides user based access so that every user can log in and visualize various data (depending on access rights). It requires PostgreSQL, Apache with mod_auth_pgsql, Perl(Net::SNMP), and RRDTool.
The Firewall Tester is a tool designed for testing firewalls' filtering policies. It includes an Intrusion Detection System testing feature, along with a packet generator tool and a sniffer. Unlike common firewall testing tools or packet generators, ftester is capable of generating network traffic that will look like real connections to the firewall or IDS system tested, which allows users to test stateful inspection firewalls (like netfilter or ipfilter) and IDS (like snort).