Sendmail is only accepting connections from localhost (127.0.0.1 IP)

Posted on in Categories FAQ, Troubleshooting last updated May 6, 2006

Q. My sendmail service is running under Linux and whenever I try to telnet it from other LAN IP, it gives connection refuse error. If I connect it from localhost it accept connection. I can only send mail from my server only. How do I force sendmail to accept mail from other hosts/LAN ips?

A. For security reason sendmail is by default configured to accept connection from local system (127.0.0.1). This should avoid open mail relay problem.

To allow connections from ALL hosts/LAN IPs open sendmail.mc file (login as the root):

# vi /etc/mail/sendmail.mc

Look for line that read as follows:

DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA’)dnl

Comment or remove above line and insert new line that read as follows:

DAEMON_OPTIONS(`Port=smtp,Name=MTA’)dnl

Above line will force to accept connection from any host. Save the file. Regenerate sendmail configuration file using m4:

# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

Restart sendmail service :

# /etc/init.d/sendmail restart

Caution: You should configure firewall and other Sendmail Anti-Spam configuration control to avoid problems.

See also:

FreeBSD: Becoming Super User (su) or Enabling su Access For User Account

Posted on in Categories FreeBSD last updated February 23, 2005

The superuser is a privileged user with unrestricted access to all files and commands. The superuser has the special UID (user ID) 0. You need to become super user (root) only when tasks need root permissions. Here is how to become a super user:
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