This the subset of my projects that I feel are the best examples of my work. The full listing of my public projects might also be of interest - it is very much a mixed bag of complete projects, archived scripts, snippets and trivial wrappers around functions I wanted to use at the command line.
Tcping is a TCP based ping variant, which measures the time it takes to open a TCP connection to a specified server. I started the project in 2005, and I have been handling feature requests, bug reports and the occasional patch since then. It is written in C++.
Tcproute is a WinPcap based C# program that implements a TCP traceroute usings its own (albeit very minimal) TCP layer.
Mturoute is a command line utility that determines the maximum transmission unit size for each (traceroute) hop between you and a given IP address. It was written to debug some packet size issues I was having over VPN links. As a companion piece, I also created 'the MTU eyechart' - a webpage with each image designed to report its own size. From a customer-interaction standpoint the latter project may be more practical.
Rawsniff is a command line packet sniffer. It uses a raw socket rather than WinPcap, which severely limits the traffic it is able to sniff - however it can be deployed immediately without installing drivers on the target machine or setting up an external machine on a hub or span port.
Subnet Abacus is a graphical IPv4 subnet calculator. Its primary conceit is that all of the informational elements are connected - you can edit the subnet in any matter you prefer and see how that affects the other information.
"ips" is a unix-style text utility. I would compare it most directly to 'grep'. Rather than matching using regular expressions, however, ips examines the input in a math and range aware manner. For instance, if you are searching for a specific address, ips will return lines that specify address ranges that include that address despite it not being present in the document as an exact text match.
Deadbit is a tool that attempts to test a router's memory over ICMP. It makes some assumptions about how a router will handle ICMP packets and attempts to feed the router all possible data bits, checksum calculations and sequence numbers. (I realize this is far from a *real* memory test, but it did in fact successfully implicate the questionable hardware it was written to test.)
WhatIsMyProxy.com is my proxy server debugging site. At face value it is simply parsing the http headers, but there isa custom server behind the scenes that enables some of the more advanced tests.
DNS Paranoia is a DNS server which is designed to debug DNS traffic. It runs a custom Python backend and gives deliberately false answers when queried.