What processes are on the ends of a TCP connection?

[Vic Abell]

I've tried fstat on our 4.3BSD, ULTRIX 2.2, DYNIX 3.1[24] and SunOS 4.0
systems.  It works on 4.3BSD (pre-Tahoe) with no change.  It requires one
change to compile under ULTRIX 2.2.  It does not compile under SunOS 4.0
or DYNIX 3.1[24], because of proc structure and header file differences -
e. g., proc.p0br, vnodes versus inodes/gnodes, etc.

Fstat's output is very useful.

It is not lint free (why do people distribute programs that don't pass
lint?), and lint shows an elementary argument handling error in its
rerr2() function (easy to fix.)