A customer running Windows is having issues with two server components that communicate with each other using TCP. Normally the two components live on two separate server, so Wireshark lets me easily see all of the communications at the byte level, however in this case the components must live on the same server.
Wireshark offers a few suggestions for capturing over the loopback interface, but I am hesitant to ask the customer to install the Loopback adapter (which may not even work according to that page) or mess with the routing tables of a production machine.
I was thinking that my best bet might be some sort of logging TCP Proxy (I saw a similar thread here) but I would need one that can log the individual bytes (so that I can happily analyze them later with a hex editor). I can probably write one in less than an hour, but I'm sure someone out there (I just can't find it) has already done a much better job than I can do for this one-off project, and I can't be the only person with this type of issue.