backup

Christopher K. Johnson ckjohnson at gwi.net
Fri Jun 18 13:06:11 UTC 2004


Steffen Kluge wrote:

>On Thu, 2004-06-17 at 22:59, Christopher K. Johnson wrote:
>  
>
>>SSH port forwarding is _not_ the same thing as ppp over SSH.
>>    
>>
>
>How not? It is still tcp-over-tcp tunneling, is it not?
>
>Cheers
>Steffen.
>
>  
>
ssh port forwarding involves 3 tcp sessions:
The session between tcp connection initiator and local ssh
The session between ssh client and sshd of course
The session between remtoe sshd and target of the port forwarding

The ssh client to sshd connection carries the tcp data payload, and 
signals opening and closing port forwarded connections, but does not 
simply forward packets for a client to target tcp session.

Traces of the unencrypted packets at both ends show different sequence 
numbers and acknowledgements, RSTs if necessary, etc.  There is not a 
1-1 correlation between tcp packets at local and remote ends of the 
port-forwarded connection.  There is only a 1-1 correlation between the 
data exchanged over the local and remote tcp sessions.

-- 
-----------------------------------------------------------
   "Spend less!  Do more!  Go Open Source..." -- Dirigo.net
   Chris Johnson, RHCE #807000448202021






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