SOCKSv6 and OpenSSH

Vladimir Olteanu vladimir.olteanu at
Tue Sep 1 00:37:39 AEST 2020

Hi there,

I'm Vladimir Olteanu (or just Vlad, for short), and I'm working on the 
SOCKSv6 protocol. It is being discussed at the IETF 
( The spec 
has matured somewhat and is currently undergoing an adoption call at the 
Intarea WG.

I would like to get your opinion on this newer version of the protocol, 
in particular on how it would work for OpenSSH and what features and 
tweaks you'd like to see included.

Version 6's core functionality is roughly equivalent to v4. It is 
extensible and has several optional features, like:

  * 0-RTT authentication

  * A setsockopt()-like mechanism (which can notably be used to request TFO)

  * Full support for hosting TCP services behind the proxy

  * DNS proxy

  * Protection against replays

  * Zero (or even negative!) RTT overhead compared to connecting to the 
server directly, assuming the proxy is on path

There's also an implementation available on Github:

  * Message library:
  * Utility library:
  * TCP proxy and transparent proxifier:

The libraries are written in C++, but also have C bindings, so they 
could be used for a potential OpenSSH + SOCKSv6 prototype.



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