Syngin
01-24-2006, 01:25 PM
For anyone interested, I've figured out the easiest way to bypass port 25 SMTP blocking. (this was imperative for our company as we have a large sales force that is not very technically proficient and are constantly switching ISPs).
Iptables is required for this. Essentially, I just added an iptable rule that accepted smtp connections on port 3025 and then routed them to port 25 internally.
/sbin/iptables -t nat -I PREROUTING -p tcp --dport 3025 -j REDIRECT --to-port 25
Sounds simple but it took me a while to get this right. I came across tons of long winded howtos regarding this but this was the simplest (assuming you already had a working email server in place)
Iptables is required for this. Essentially, I just added an iptable rule that accepted smtp connections on port 3025 and then routed them to port 25 internally.
/sbin/iptables -t nat -I PREROUTING -p tcp --dport 3025 -j REDIRECT --to-port 25
Sounds simple but it took me a while to get this right. I came across tons of long winded howtos regarding this but this was the simplest (assuming you already had a working email server in place)