OpenSSH_6.7p1 Debian-5+deb8u2 unix socket forwarding: Warning: remote port forwarding failed for listen path /home/sithglan/.gnupg/S.gpg-agent

[Thomas Glanzmann]

Hello everyone,

> (x1) [~] ssh -o "StreamLocalBindUnlink=yes" -R /home/sithglan/.gnupg/S.gpg-agent:/home/sithglan/.gnupg/S.gpg-agent remote.machine.de
> Warning: remote port forwarding failed for listen path /home/sithglan/.gnupg/S.gpg-agent

to answer my own question. StreamLocalBindUnlink exists for client and
for server. In order to make a remote port forwarding work with an
existing socket, it needs to be enabled in the server, not in the
client. So the following works:

(infra) [~] grep StreamLocalBindUnlink /etc/ssh/sshd_config
StreamLocalBindUnlink yes
(infra) [~] /etc/init.d/ssh restart
Restarting OpenBSD Secure Shell server: sshd.

Afterwards it works like a charm.

Cheers,
        Thomas