forwarding features

Jon Peatfield J.S.Peatfield at
Wed Nov 20 04:37:34 EST 2002

While messing with various tunnels it occured to me that there may be
cases where some extra tunneling functionality would come in handy.  I
thought I better run it past the list before trying to implement a
patch since the last 2 times I did this there was another way to
get the effect I wanted with no code changes...

  Forwarding should not just be of AF_INET but (where available)
  AF_UNIX (ie forwarding unix-domain sockets).  The syntax might be a
  little messy though.

  The ability to set up forwardings at any point, e.g. ssh to a host
  which runs some code to determine which ports need forwarding and it
  asks the sshd to negotiate with the client, or a user might want to
  add a new forwarded connection by typing some ~ stuff from the
  client end...

The reason I've been thinking about this is that I need to be able to
set up a -R tunnel, but I don't know the port to listen on since
someone else may already be using that port (well I can select the
port at random, but that isn't safe either -- perhaps port 0 should
ask sshd to select any free port).  If I could port-forward
unix-domain sockets then the name could be guarenteed unique,
similarly if the forwarding could be added after running code we would
be ok too.

[ Well I could do it with external code at both ends I suppose, but
that just makes it harder to run on some platforms ... ]

Jon Peatfield,  DAMTP,  Computer Officer,   University of Cambridge
Telephone: +44 1223  3 37852    Mail: J.S.Peatfield at

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