iptables NAT entry times out but connects from firewall

iptables NAT entry times out but connects from firewall

[Hanasaki JiJi]

There is a firewall with two NICs and the below rule to allow an 
internal host to connect out to smtp servers on the internet.  Some 
hosts have a connection timeout on a connect from $INTERNAL_IP_OF_SMTP 
yet connect from the firewall just fine.

iptables -t nat -A POSTROUTING -p tcp -o $NIC_EXTERNAL \
        --dport 25 -s $INTERNAL_IP_OF_SMTP -j MASQUERADE

ex:
on firewall:
	telnet csoc-mail-msfc.csoconline.com 25
	
	above connects ok

on $INTERNAL_IP_OF_SMTP
	telnet csoc-mail-msfc.csoconline.com 25

	connection times out

Re: iptables NAT entry times out but connects from firewall

[Harald Welte]

[-- Attachment #1: Type: text/plain, Size: 913 bytes --]

On Mon, Apr 28, 2003 at 12:57:16PM -0500, Hanasaki JiJi wrote:
> There is a firewall with two NICs and the below rule to allow an 
> internal host to connect out to smtp servers on the internet.  Some 
> hosts have a connection timeout on a connect from $INTERNAL_IP_OF_SMTP 
> yet connect from the firewall just fine.

this seems to be an iptables usage problem, please follow-up to the
netfilter mailinglist at netfilter@lists.netfilter.org.

for more information, plaese see the netfilter homepage at
http://www.netfilter.org

-- 
- Harald Welte <laforge@netfilter.org>             http://www.netfilter.org/
============================================================================
  "Fragmentation is like classful addressing -- an interesting early
   architectural error that shows how much experimentation was going
   on while IP was being designed."                    -- Paul Vixie

[-- Attachment #2: Type: application/pgp-signature, Size: 232 bytes --]