We'll need this when we have a SockWrapper pointing at a Mux on a subprocess
pipe.

Currently the 'server' is just a pipe to run 'hd' (hexdump) for looking at
the client-side results.  Lame, but true.

Now if we aren't given an explicit port, we always initiate the port search
at 12300 and count upward looking for an available port.

Normally the kernel will assign us a random port, but that's not ideal
in our case because we'd like to use the same port numbers whenever
possible; that avoids piling up crap inside iptables in the (hopefully
unlikely) event that we die without cleaning up correctly.

Doing it in python instead of shell makes the code a bit less error prone.
Plus we can parse the iptables output and avoid triggering iptables errors.

When regenerating outgoing connections, we set TTL=42 to prevent re-proxying
of requests.  That's a little hacky, but at least it avoids infinite loops.

Importing options.py, ssh.py, and LICENSE from the bup project.