Server allocating port number for -R ?

Damien Miller djm at
Tue Jan 3 11:22:51 EST 2006

Wim Livens wrote:
> I'm looking for a way to have the server allocate an available port
> number when using remote port forwarding.  
> In draft-ietf-secsh-connect-25.txt such a feature is described but I
> fail to see if/how this is actually supported by openssh.
> Quote from the draft:
>    If a client passes 0 as port number to bind and has 'want reply'
>    TRUE then the server allocates the next available unprivileged port
>    number and replies with the following message, otherwise there is
>    no response specific data.
> Naively doing things like -R0:host:hostport fail with a "Bad
> forwarding port(s)" message.

This isn't supported at present, but there is a patch that we will
probably look at in the next release cycle:


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