Looking in /bin, I see a load of things I recognise, together with the
trivial scripts `ro', `rw', `rwm', `rom' and unexecutable `x'. But
what is `userver'? at 367K, it's big enough to do something substantial.
The usage message isn't too helpful:

userver: usage: userver [-dlL1w02] [-p <file>] [-m <maximum>]
[-R <directory>] [-U <user-spec>] [-C <directory>]
[-t <time-spec>] [-a <token>] <local-address> <command> [<arg> ...]

but it suggests some sort of remote file serving capability, as do some of
the internal strings. All my attempts to run it produce one of two error messages:
opening socket: Unrecognized UNSN protocol name
opening socket: Unsupported protocol combination in UNSN

Any ideas? I'm surprised it hasn't been mentioned before, but the bbs search
turns up only a post with a list of the contents of /bin.