On 08/19/12 17:13, Steve La Rocque wrote: > Hi James. Can you do a $ telnet [destination] 25 > from the other lan to the machine? If you can, then at least it > shouldn't be a network firewall issue. If not, can you ping the mail > machine from the other lan? If not, perhaps you have a routing > problem. Also, you may have smtp configured such that it only pays > attention to lan connection requests, although that is less likely. > > -Steve > > > On 08/19/2012 05:11 PM, James wrote: >> Both computers run Linux. >> >> A port scan of the machine with the open port 25 from inside the same lan. >> >> PORT STATE SERVICE >> 25/tcp open smtp >> >> port scan from the web >> port 25 is open >> >> port 25 can receive mail. >> >> A port scan of the machine with the open port 25 from my lan. >> PORT STATE SERVICE >> 25/tcp filtered smtp >> I can't telnet to port 25 of the computer on the other lan so it is hard to debug it. >> I tried making this computer a DMZ. I can't ping the mail machine from the remote LAN but I can SSH to it. I can telnet to the mail machine from the same LAN it is on. Could my ISP be blocking me from telnetting to port 25 on the mail machine?