integrit is an alternative to file integrity verification programs like tripwire and aide. It helps you determine whether an intruder has modified a computer system. integrit's major advantages are a small memory footprint and simplicity. It works by creating a database that is a snapshot of the most essential parts of your computer system. You put the database somewhere safe, and you can then use it to make sure that no one has made any illicit modifications to the computer system. In the case of a break in, you know exactly which files have been modified, added, or removed.
The IPchains Firewalling Module, part of the RockSolid Linux Distribution, allows you to easily maintain a firewall based on ipchains with the Webmin look and feel. It has three modes: Newbie (select one of five security levels), Template (define from a table with protocols and directions what should be allowed to pass your firewall), and Expert (have the real ipchains experience by having every parameter under control by editing a script file which has all ipchains rules). Nearly all of the ipchains options are supported.
iplog is a TCP/IP traffic logger. Currently, it is capable of logging TCP, UDP, and ICMP traffic. iplog is able to detect TCP port scans, TCP null scans, FIN scans, UDP and ICMP "smurf" attacks, bogus TCP flags, TCP SYN scans, TCP "Xmas" scans, ICMP ping floods, UDP scans, and IP fragment attacks. iplog is able to run in promiscuous mode and monitor traffic to all hosts on a network. iplog uses libpcap to read data from the network and can be ported to any system that supports pthreads and on which libpcap will function.
iptables is built on top of netfilter, the packet alteration framework for Linux 2.4.x and 2.6.x. It is a major rewrite of its predecessor ipchains, and is used to control packet filtering, Network Address Translation (masquerading, portforwarding, transparent proxying), and special effects such as packet mangling.
iSSL (independant Secure Sockets Layer) is a minimalistic cryptographical API that uses the RSA and AES ciphers to establish SSL-alike, secure encrypted communications between two peers communicating through a network socket, including session key generation and public key exchange.
ITS4 is a command-line tool for statically scanning C and C++ source code for security vulnerabilities. ITS4 scans through source code for potentially dangerous function calls that are stored in a database. Anything that is in the database gets flagged. ITS4 tries to automate a lot of the grepping usually done by hand when performing security audits.
JFwadmin is a Java 2 high-level X11 tool for ipchains. The GUI displays easy-to-understand services. Features include scripts generation, firewall save and restore, automatic interface and IP address and routes detection, current firewall configuration display, and handling of masq-modules and port-forwarding.