6jack is a framework for testing, analyzing, and fuzzing network applications. 6jack runs a command, intercepts calls to common network-related system calls, and passes them through an external filter. A filter can be written in any language supporting the MessagePack serialization library. 6jack is especially useful for writing tests for clients and servers, debugging and reverse engineering protocols, sketching filtering proxies, and fuzzing.
PinkTrace is a lightweight C library that eases the writing of tracing applications. It consists of Wrappers around different ptrace() requests, an API for decoding arguments (strings, socket addresses, …), and an experimental API for encoding arguments. PinkTrace aims to be a cross-platform library for writing tracing applications.
geoipgen is an IP network tool for generating geotargeted lists of IP addresses using MaxMind's GeoLite Country database. It can randomly enumerate all IP addresses or a specified number of IP addresses in a particular country or a list of countries. For example, to get all IPs for Japan in a random order, use "geoipgen jp". For a sample of 10,000 IPs from Australia and New Zealand, use "geoipgen -n 10000 au nz".