Re: simple port forwarding question

[SBlaze <dagent.geo@yahoo.com>]

--- Rohit Kumar Mehta <rohitm@engr.uconn.edu> wrote:
> 
> Hi guys, I was wondering if someone could help me out here.  I am fairly 
> well confused after trying to muddle through
> this tutorial:
> http://iptables-tutorial.frozentux.net/iptables-tutorial.html
> 
> I think what I want to do should be easy.  Perhaps someone could help.
> 
> We are trying to trick the systems into believing that the Kerberos 5 
> server is on IP#2 (let's call it 192.168.28.3)
> but it is in fact on IP#1 (192.168.28.2).
> 
> Maybe my attempted iptables commands will make it blatantly obvious what 
> I am trying to do:
> 
> iptables -t nat -A PREROUTING --dst 192.168.28.3 -p tcp --dport 88 -j 
> DNAT --to 192.168.28.2
> iptables -t nat -A PREROUTING --dst 192.168.28.3 -p udp --dport 88 -j 
> DNAT --to 192.168.28.2
> 
> iptables -t nat -A POSTROUTING -p udp --dst 192.168.28.2 --dport 88 -j 
> SNAT --to-source 192.168.28.3
> iptables -t nat -A POSTROUTING -p tcp --dst 192.168.28.2 --dport 88 -j 
> SNAT --to-source 192.168.28.3
> 
> iptables -t nat -A OUTPUT --dst 192.168.28.3 -p tcp --dport 88 -j DNAT 
> --to-destination 192.168.28.2
> iptables -t nat -A OUTPUT --dst 192.168.28.3 -p udp --dport 88 -j DNAT 
> --to-destination 192.168.28.2
> 
> 
> Basically we want it so that if I do a "telnet 192.168.28.3 88", I get a 
> connection to "192.168.28.2:88"
> This works - when I initiate the connection from 192.168.28.3, but from 
> any other machine on the network
> it does not work.
> 
> Am I doing something wrong or forgetting a key step?  Thanks!
> 
> Rohit
> 
> 

I think you left out one important bit of information here. Are these two ips
on the same box? ( ie .1 on eth0 and .3 eth1 ) If they are I think it would
mean all the world of difference for your ruleset. you might be using the NAT
table when FOWARD lines in your filter table would sufice...

just a guess...

SBlaze

=====
In the absence of order there will be chaos.

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