[plug] routing packets in iptables

[Andrew Furey]

On 01/04/2009, Jon L. Miller <jlmiller at mmtnetworks.com.au> wrote:
> I'm trying to get my Blackberry Storm to pickup mail from our internal
>  server.
>  I'm needing some help in routing imap packets from a external internet
>  server with a iptables firewall running to an internal mail server.
>  What I have on the external server's firewall is:
>  EXT_IFACE = 'eth0'
>
>  $IPT -A FORWARD -p  tcp --dport 143 -j ACCEPT
>
>  $IPT -t nat PREROUTING -i $EXT_IFACE -p tcp --dport 143 -j DNAT
>  --to-destination 192.168.10.55 [internal mail server]

It looks like you're missing a -A from that second, to actually add
the rule (is probably giving a syntax error) - so

$IPT -t nat -A PREROUTING -i $EXT_IFACE     etc.

Also, is the internal server's routing set to send the replies back
that way (eg having the external machine as the default gateway)? Just
something to think about depending on how complex your network setup
is...

HTH
Andrew

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