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Hi all,

I have a problem with sendmail to which i didn't find the answer for some time.

Problem :
My linux box is both on Internet and Internal network with 2 different NICs.
I can send mails from internal network but I can't from internet.

Configuration :
Let's say my internet @ is i.i.i.i and my private network is p.p.p.p
From the private network, i can telnet sendmail (port 25) on BOTH NICs. From outside, sendmail doesn't seem to be listenning at all (connection timeout).

Could it be some restrictions on port 25 for external connections ?

Thx,
JC

You are using sendmail, right?
Check /etc/sendmail.cf file and locate the line which says DaenonPortOptions, you might have it only allow local net, you should change it to listen to all connections (therefore from outside), it should read as:

O DaemonPortOptions=Port=smtp,Addr=0.0.0.0, Name=MTA
and

And if you have client machines outside your local net to use the SMTP server for outgoing emails (relay), then you must also modify the line in sendmail.cf, so it read like:

# SMTP client options
O ClientPortOptions=Address=0.0.0.0

Let me know what is your final result. regards.

He must have used Redhat 7.1.
I know Redhat disabled Sendmail to listen on public IP in 7.1 version by design to strengthen security.

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Thanks for your replies.

I tried the commands you suggested in sendmail.cf
ClientPortOptions is not recognized by my 8.9.3 sendmail
The "DaemonPortOptions" was regognized though, but i'm still unable to open port 25 from external addresses.

I am running mandrake 6.5 (Linux version 2.2.13-7mdk)

Investigating that problem, I figured out sendmail was not using regular TCP wrapper as other services do. Should I try to include it in inetd scope ? ( As other services don't have restrictions on calling addresses, I would expect the same availability for sendmail)

Do you get any errors, such as connection refused etc?
Do you get a ping rely from the linux machine or traceroute to to it from the external ip?
I ask this because I cannot tell whether you have connectivity problem or you have configuration problem.

This is not a connection problem.
This machine IS accessible from outside (this is my mail server !)
I can open any other services from internet (telnet, httpd, mysqld, ...) it's just that I can't open a connection on port 25 from outside !

I would suggest you to test by initiating a telnet to port 25 to the Linux box, and try to use netstat or tcpdump and observe what is going on with the Linux box. Perhaps from there, you'll be able to ping point where the problem is. Good luck.

Of course you do the telnet test from external network.

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Of course