EHLO command takes virtual IP address

SUSE Linux Enterprise Server SLES Networking
1

Hello Experts,

I have a SUSE 11SP3 in which my apps team is trying to send emails but the SMTP server rejects the traffic from this server. A detailed trace shows that the traffic is going to SMTP server through the virtual IP configured on the physical interface. Actually it has to go through the physical interface. SMTP server was configured to accept the connections from IP/hostname configured on the physical interface.

We tried telnet to the SMTP server with port no 25,

szcld01:/etc # telnet LTC-SMTP-RELAY-PRI.ABCD.NET 25
Trying 10.179.2.166…
Connected to LTC-SMTP-RELAY-PRI.TWUTIL.NET.
Escape character is ‘^]’.
220 EXHWP02.TWUTIL.NET Microsoft ESMTP MAIL Service ready at Wed, 11 Nov 2015 06 :46:46 +0000
ehlo
250-EXHWP02.TWUTIL.NET Hello [10.179.56.242] ===========>>>>>>> this is the virtual IP
250-SIZE
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES

So the apps team suspects this could be the issue behind the problem. My physical IP is 10.179.56.221

Can anyone help me to resolve this?

2

maybe this can help…

https://kindlund.wordpress.com/2007/11/19/configuring-multiple-default-routes-in-linux/

also if you use postfix you can configure its helo name as well

smtp_helo_name = test.smtp.com

Michael.

3

Hi jineeshc,

SMTP server was configured to accept the connections from IP/hostname configured on the physical interface.

assuming that you run Postfix, to what value is “inet_interfaces” set in /etc/postfix/main.cf?

Regards,
Jens

4

Thanks Jens and Michael.

Actually the issue turned to be a wrong subnet mask on the virtual IP. I had 255.255.252.0 on the physical IP and 255.0.0.0 on the virtual IP.I configured same subnet on the virtual IP as on the physical. Now my traffic is going through the physical IP.

Thanks again for your help.

5

Hi jineeshc,

thank you for reporting back - this indeed does explain the behavior and I will add that to my internal list of items to check in similar cases :slight_smile:

Regards,
Jens