fwsnort translates snort rules into an equivalent iptables ruleset. By making use of the iptables string match module, fwsnort can detect application layer signatures which exist in many snort rules. fwsnort adds a --hex-string option to iptables, which allows snort rules that contain hex characters to be input directly into iptables rulesets without modification. In addition, fwsnort makes use of the IPTables::Parse Perl module in order to (optionally) restrict the snort rule translation to only those rules that specify traffic that could potentially be allowed through an existing iptables policy.
Endian Firewall is an all-in-on Linux security distribution that turns any system into a full-featured security appliance. It features a stateful packet inspection firewall, application-level proxies for various protocols (HTTP, POP3, SMTP), anti-virus support, virus and spam filtering for email traffic (POP and SMTP), content filtering of Web traffic, and a "hassle free" VPN system based on OpenVPN.
fwknop implements an authorization scheme called Single Packet Authorization that requires only a single encrypted packet to communicate various pieces of information, including desired access through an iptables, ipfw, or pf firewall policy and/or specific commands to execute on the target system. The main application of this program is to protect services such as SSH with an additional layer of security in order to make the exploitation of vulnerabilities much more difficult. The authorization server works by passively monitoring authorization packets via libpcap. Also supported is a robust port knocking implementation based around iptables log messages.
The Userspace Logging Daemon (ulogd) is a flexible framework for extensive logging of packets on a firewall machine. ulogd uses the ULOG target of iptables/netfilter, the packet filtering framework of Linux 2.4 and 2.6. It supports binary plugins for adding packet interpreters and output-targets (e.g., for logging into databases, user-defined filetypes, etc.).
FireHOL a simple yet powerful way to configure stateful iptables firewalls. It 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, and all kinds of NAT. It provides strong protection (flooding, spoofing, etc.), transparent caches, source MAC verification, blacklists, whitelists, and more. Its goal is to be completely abstracted and powerful but also easy to use, audit, and understand.
The Network Security Policy Compiler (NetSPoC) is a tool for security management of large computer networks with different security domains. It generates configuration files for packet filters controlling the borders of security domains. It provides its own language for describing security policy and the topology of a network. The security policy is a set of rules that state which packets are allowed to pass the network and which are not. NetSPoC is topology aware; a rule for traffic from A to B is automatically applied to all managed packet filters on the path from A to B.
ike-scan discovers IPsec VPN servers, and can fingerprint them using UDP backoff and Vendor ID fingerprinting techniques. It supports IKE Main Mode and Aggressive Mode. ike-scan allows flexible specification of the outgoing IKE packet, and decodes the response packets. It also supports pre-shared key cracking for IKE aggressive mode with pre-shared key authentication.