Bypassing ISP Port 25 blocking


Results 1 to 2 of 2

Thread: Bypassing ISP Port 25 blocking

  1. #1
    Join Date
    Oct 2001
    Location
    /canada/ont/windsor
    Posts
    1,499

    Bypassing ISP Port 25 blocking

    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)
    Where are we going and why am I in this handbasket?
    (No trees were killed in posting this message. However, a large number of electrons were seriously inconvenienced.)
    ----------------------------------
    Debian user since Potato
    Syngin: Web Portfolio

  2. #2
    Join Date
    Sep 1999
    Posts
    3,202
    Or just use smtpauth... runs on 589 IIRC..

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •