SOCKS Server and Library for Java. Support for versions 4 and 5 of SOCKS protocol. Designed to be easily expandable to support different encryption/authentication/authorization methods. Sample server and client are available.
A very simple to use java firewall testing tool. Ever wanted to verify that a TCP or UDP network path is actually open? This tool has both server and client modes so you can test network paths between any two computers that have the Jave JRE installed.