The uscpi-tcp package is Bernstein's implementation of something called UCSPI: the UNIX Client/Server Program Interface. We are told that UCSPI should be pronounced ooks-pie, although to my eye it looks more like ucks-pee.

Oh, well, that's the djb way for you...

However you pronounce it, ucspi-tcp is an essential part of the djb way. It is nearly as important as daemontools in setting up a foundation for our server. In fact, the two packages go together hand in glove as we add TCP/IP services to our server.

ucspi-tcp also happens to be a lot of fun. The utilities in this package make it extremely easy to add custom client/server applications, both useful and frivolous.

The ucspi-tcp package is a prerequisite for installing and using many of the other package described at this site. Building a server the djb way is going to have a lot to do with knowing and using the suite of utilities included with ucspi-tcp.