Hi
I've created an open source application I think you might find handy. It's called “Why Can't I Connect?” and as the name implies, it is used primarily to find TCP/IP connectivity problems. I have presets for common server types: Microsoft SQL, MySQL, FTP, SFTP, IMAP, POP3, SMTP, IRC, LDAP, and Usenet. You may also create a generic client to any server and port as well as create a generic server / listening socket on any available port. There is the ability to insert my application between existing clients and servers (bridging.) There is a handy tool for resolving names to IP addresses and IP addresses to names. There is also the ability to create arrays of listening sockets.
The application is released GPLv3 and free to download. I've tested it in Fedora and Ubuntu Linux, Windows XP, Vista, and 7. I've created a 32 bit rpm and deb, however, 64 bit systems should compile from source. I will continually be adding more functionality. Here's the link if you're interested:
http://sourceforge.net/projects/wciconnect/
