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.
PHREL is a per host rate limiter. It will track the rate of incoming traffic on a server and insert a chain into iptables when a configured threshold is crossed. The inserted chain may either rate limit or block the offending host for a period of time. The inserted chain is automatically removed when the offending host's traffic levels return to normal. PHREL is particularly well suited to protecting nameservers (DNS) from random hosts that flood requests, and to preventing SSH brute force login attempts.
fwlogwatch is a packet filter and firewall log analyzer with support for Linux ipchains, Linux netfilter/iptables, Solaris/BSD/HP-UX/IRIX ipfilter, Cisco IOS, Cisco PIX/ASA, Netscreen, Elsa Lancom router, and Snort IDS log files. It can output its summaries in text and HTML and has a lot of options. fwlogwatch also features a realtime anomaly response capability with a Web interface.
HTTPTunnel is a simple client/server application for creating an HTTP tunnel between two machines, optionally via a Web proxy. This tunnel can then be used to wrap arbitrary TCP socket traffic in HTTP, thus allowing communications even through a restrictive firewall that only allows outgoing HTTP connections.