UNIX UCSPI protocol definition
Copyright (C) 2000
Bruce Guenter <bruceg@em.ca>

This document defines the UNIX protocol for UCSPI tools. A UNIX client
communicates with a UNIX server on the same machine through a
local-domain stream socket.  See http://cr.yp.to/proto/ucspi.txt for
further details on the UCSPI standard.

Both the client and the server set up the following environment
variables:

  PROTO the string "UNIX"
  UNIXLOCALPATH is the path associated with the local-domain socket
  UNIXLOCALUID is the UID of the local process
  UNIXLOCALGID is the GID of the local process
  UNIXLOCALPID is the PID of the local process
  UNIXREMOTEEUID is the effective UID of the remote process
  UNIXREMOTEEGID is the effective GID of the remote process
  UNIXREMOTEPID is the PID of the remote process

Note that the remote variables are only supported on operating systems
that support some way of identifying the process connecting to a socket.
For now this is limited to Linux kernel 2.1 or later with SO_PEERCRED
support.