Hello

I have a server at home and one very small server in a datacenter.

I use iptables with NAT to forward the server in the datacenter to my server at home.

The problem is, when I want to forward the port 25. It's work when I use this rule :
But, with this rule, all input traffic use the datacenter server's IP (For example, I can't see my IP in the access.log, but I see the datacenter server's IP)

When I use this iptables rule, all seems to work:
The HTTP traffic work, IMAP, POP too, but not the SMTP traffic : I get a connection refused

I use theses iptables rules to forward ports to my home server's IP address :
I think the packet is lost because it never reach the mail server.

Thanks for any help !

Is it possible your DC's ISP routes port 25 traffic to their own smarthost?

No, when I telnet to my home server's address IP via my datacenter server, it's work.

When you do that successful telnet, are you going to port 25? Many ISPs do not allow port 25 traffic on residential accounts.

When I do telnet on port 25 that's work. Only if I use my home ip adress or the server ip address when I use the first masquerade rule.

It's when I specify a source IP in the masquerade it block.

My ISP block the outgoing traffic, but it's not a problem.

When I use the dedicated server IP with the source option (-s) in the masquerade rule:
When I telnet to my home IP from the dedicated server :

When I telnet to my server IP from a friend's server with no source option to my iptable rule:

The is problem with this rule is when I specify no option in the masquerade rule, all IPs are rewritten by 178.33.197.xxx (INPUT and OUTPUT)