yxorp is a reverse proxy and application level firewall for the HTTP protocol. It can do all kinds of checks on HTTP traffic, and is highly configurable. It also has other functions that are useful for a web frontend, like load balancing.
The Nemesis Project is designed to be a command line based, portable human
IP stack for UNIX-like and Windows systems. The suite is broken down by
protocol, and should allow for useful scripting of injected packets from
simple shell scripts.