Hi,
I have an DNAT ISSUE with PREROUTING.
This is my setup.
I have 2 firewalls running iptables.
Pls asume 1.2.3.4/29 is the internet interace of FIRST firewall. 2.3.4.5/29 is the internet interface of SECOND firewall. it has DMZ zone. in that DMZ zone, mail server runnig @ 192.168.100.3
Now I want to DNAT port 25 of FISRT firewall (i.e - its ip address - 1.2.3.4/29) to the internet ip address ( 2.3.4.5/29) of SECOND firewall. That firewal DNATs port 25 to mail server @ 192.168.100.3 in DMZ zone.
These are rules I have added.
FIRST firewall (its internet ip address - 1.2.3.4/29) I have addes below rule.
iptables -t nat -A PREROUTING -p tcp -i eth0 -d 1.2.3.4 --dport 25 -j DNAT --to-destination 2.3.4.5:25
That should forward port 25 to SECOND firewall. in SECOND firewall, I have added 2 below rules.
iptables -t nat -A PREROUTING -p tcp -i eth0 -d 2.3.4.5 --dport 25 -j DNAT --to-destination 192.168.100.3:25
iptables -A FORWARD -p tcp -d 192.168.100.3 --dport 25 -m state --state NEW -j ACCEPT
Now, it should forward port 25 to mail server @ DMZ Zone.
I think I have added these rules properly. But, It does not work.
I checked from outside world . I telneted to port 25 of first firewaal. Then, It should forward to mail server @ DMZ zone. But, no responce.
WHY is that?
YOUR IDEAS?