Re: Slow PPP/SLIP bug: Found change that caused problem

Jared Mauch (!
Sat, 6 Apr 1996 17:27:14 -0500 (EST)

Hey Alan (et al...)

Gentlemen - Could we please have some attributions here. I missed
the early part of this "yes - no - yes - no" and it's hard to figure out who
the players are.

Alan Cox enscribed thusly:

> > : > ssh has its own packet handling and bypasses TCP.
> > : No
> > Yes. SSH uses TCP socket number 20 to establish the connection but then
> > switches to something they call the "binary protocol" to do the
> > actual transmissions in a secure way.

Socket 20???? That's not ssh - that ftp-data!

Something WHO calls "binary protocol"? I've been working with and on
ssh since version 1.0.0 (currently 1.2.13) and I've yet to run into that term.

> No

I agree with Alan and will futher emphasize his point. NO!
Ssh uses port 22 - period. Port 20 is allocated for ftp data and is
not used by ssh. I've been on the ssh mailing list for some time
and helped Tatu out with the testing of ssh on both Linux and on C2
Secure SCO UNIX where there was some collaboration over some peculiar
patches for SCO. That includes being up to my eyeballs in the sources
early on trying to get the blinken thing to work or even compile on SCO
with the SecureWare C2 stuff! I've also set up firewalls allowing ssh
transports and I can assure you - it uses 22. It does NOT use 20. It can
cooperate with other protocols and ports to provide forwarding but it does
NOT use them for transport. And it certainly does NOT bypass TCP - it's
a TCP protocol that uses it and runs over it!

I'm not sure what you (other you - not you, Alan) think this "binary
protocol" might be unless you're confusing it with the forwarding
support which ssh provides to forward other protocols (such as X-Windows)
over ssh. It has it's own protocol which does support encapsulation
of other protocols and tunneling through a secure channel, but ssh itself
is using port 22 for its connections.

If you are still confused - take it over to the ssh mailing list
( or ask Tatu Ylonen (, after all - he wrote
the thing.


 Michael H. Warfield    |  (770) 985-6132   |
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