Informing the SSH agent of the target user at server

Hector Martin 'marcan' marcan at
Thu Mar 22 03:30:31 AEDT 2018

On 2018-03-22 01:25, Peter Stuge wrote:
>> Or an intermediate forwarding ssh could insert a tag (2):
>> - SSH_AGENTC_EXTENSION "forwarded-for at" string("user2 at host2")
>> (which would of course nest with multiple chained forwards, similar to
>> SMTP Received headers)
> Since forwarding ssh processes just forward agent socket bytes
> without tracking the protocol state in that stream adding a packet
> isn't trivial.

It's reasonably trivial if the definition is that the forwarded-for
extension chain happens once when agent connections are opened. Then the
ssh process just needs to send the extension, wait for the reply
(whether positive or not-supported), eat it, and move on with forwarding
the remaining bytestream.

Hector Martin "marcan" (marcan at
Public Key:

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