iptables NAT entry times out but connects from firewall
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
Quoted 4 lines · 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.
this seems to be an iptables usage problem, please follow-up to the netfilter mailinglist at [email protected].
for more information, plaese see the netfilter homepage at
http://www.netfilter.org
Signature · 5 lines
- Harald Welte <[email protected]> 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