can telnet to port 25 using local host, not IP address

[stevenriz]

Hi, we have a linux server on a cable modem and static IP for dedicated email but port 25 is blocked for some reason. We can telnet to port 25 using localhost but not the IP address.... we've tested the following scenerios....
- stopped iptables, so it isn't iptables blocking the port
- added the ipaddress and domain to the hosts file

don't know what is blocking it. We get a connection refused message even from being logged into that box directly!! Any thoughts??

 

[ericbrunson]

Is your ISP blocking port 25?
Are you on the same subnet?
Have you stopped and restarted the mail application since turning up the interface?
Is your mail server configured to bind to all addresses?
What does the output of netstat -an tell you?

 

[stevenriz]

the only thing I havne't checked is to see if the mail app is configured to bind to all adds. How could we check that?

tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN

 

[ericbrunson]

It's only listening on localhost, otherwise you'd see a line like this:

tcp   0    0    <your-ip-address>:25    0.0.0.0:*     LISTEN

or

tcp   0    0    0.0.0.0:25    0.0.0.0:*     LISTEN

Either the mail system was started before the external interfaces were brought up, the application is only configured to listen on localhost, or the application is confused by having multiple external interfaces. I'd estimate those options to be in descending order of probablility.

 

[lgarner]

It's listening on localhost only. Which mail server are you using?

If Postfix:
Edit /etc/postfix/main.cf and change "inet_interfaces=localhost" to "inet_interfaces=all", then execute "postfix reload"

If Sendmail:
Edit /etc/mail/sendmail.cf and change the "Addr" in "O DaemonPortOptions" to "0.0.0.0". Then restart sendmail.

Both servers have forums here. forum921 for Postfix; forum14 for Sendmail.

 

[stevenriz]

just did that..... maybe I never had to do this before b/c linux was able to automatically configure the eth0 on another server during OS install and on this one we had to load the drivers manually??? You think??

Anyway, thanks you guys, it is working now......

 

[lgarner]

Could be. In my experience, having the mail service listen to localhost only is the default behaviour as it's all that you need to be a mail client.

 

[stevenriz]

ahh ok. Thanks. I was looking at some other servers to compare. this also seems to work. Do you agree with this line??

O DaemonPortOptions=Name=MTA

 

[lgarner]

That looks fine for what you want.

http://www.sendmail.org/~gshapiro/8.10.Training/DaemonPortOptions.html

has a good list of DaemonPortOptions values.

 

[chriseubank]

Try what this guy did:

http://www.gotroot.com/tiki-view_forum_thread.php?forumId=26&comments_parentId=582

Most ISP's block port 25 to avoid having blacklisted hosts on their subnets.

HTH,
C