SSH nat-forwarded

Niklas Saers Mailinglistaccount niklasmls at
Mon May 12 03:56:27 PDT 2003

I've got a firewall that forwards ports to SSH-ports on boxes it protects.
This has been good for all 4-STABLE boxes, but I've recently put up a
CURRENT box. I can SSH to the firewall and from the firewall to the
CURRENT box, but I do not get a proper connection when having it forwarded
through the firewall.

Let's say my external box 'ext' is on, my firewall 'fw' is on and my internal CURRENT-box on

'fw' masquerades using
"/sbin/natd -interface fxp0 -redirect_port 5051"

and "firewall":
 ipfw add divert 8668 ip from any to any via fxp0
 ipfw add allow ip from any to any

from 'fw' "telnet 22" gives the classic "SSH-1.99"-etc
while from 'ext' "telnet 5051" gives no greeting at all. It
listens and terminates the connection after a short while.

Any suggestions to why ssh doesn't connect correctly? I've forwarded other
ports to other services on the same box and it works flawlessly. Thus I
suspect that 'sshd' understands I've forwarded this connection and doesn't
like it the least bit. Can I turn of this hypersensitivity?



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