There was a discussion about how to find out if port 25 were open for inbound or outbound traffic. Some of the discussion was off topic, true enough so the tread was closed. The discussion actually still ended up with a conclusion, as I see it, about a quite easy way to do such a test. I hope I do not offend anybody or tyhe forum by just posting my final conclusion about how to do this, the most easy way:
Outbound traffic port 25: From linux shell or from dos shell type " telnet contribs.org 25 ". See if the mail server identifies itself.
Inbound traffric, port 25 or port x: Set up a forwarding from your external ip port 25 to server port 25, if needed, or from port x to port 25. Then go to the external scanner "shieldsup" to see if it can see your open port:
https://www.grc.com/x/ne.dll?bh0bkyd2To see if you are behind a router: Go to server shell, type " ifconfig ". Compare ip adress with:
http://www.myip.dk If ip's are different server is behind a net router and forwarding will be needed. (Adn for dos simular command " ipconfig " )
To get some more info about your network connection: From linux - " traceroute contribs.org " From Dos - " tracert contribs.org "
One other problem, lets say that the situation is that the port 25 outbound connection is actually closed, and it is required to find an alternative port for traffic outbound direction. How to do that ?
This will requre an external server for testing, for excample a remote sme server. Lets say you want to check if port 2525 is open. Then you can forward for instance port 2525 to port 80 at the remote server or remote server gateway. Then use your local web browser and type http://<romoote ip>:2525 . If you can see your remote web server, then the port is open for outbound traffic on your internet connection.
(No, there will not be any more post on this subject from my side....
)
1 Replies
6175 Views