Simple port forwarding question

[Julian Elischer]

Erik Trulsson wrote:

>On Tue, Nov 02, 2004 at 04:36:30PM -0800, John Fox wrote:
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>>Hi, folks.
>>
>>I'm experimenting, trying to setup a situation where connections 
>>to port 25 on machine A are forwarded to port 25 on machine B.
>>I've read the ipfw manpage and it looks as though what I'm doing
>>is correct.  
>>
>>
>>The IPFW rules on machine A are:
>>   00100 fwd machineB tcp from any to any 25
>>   65535 allow ip from any to any
>>
>>And there is a sendmail listening on B's port 25.
>>
>>But when I telnet to machine A's port 25, all I get is
>>a perpetual "Trying" message that just sits there.
>>    
>>
>
>Don't use "fwd" for this - it doesn't work that way (for one thing B is
>unlikely to handle an IP-packet that is still adressed to A.)
>
>Use natd and the '-redirect_port' option to natd instead - that works.
>

you can use ipfw fwd IF you also run it on the target machine to 
"capture/accept" the foreign packet.
Otherwise teh packet will be forwarded back to it's stated destination  
(or dropped).


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