Check Whether a Server Listen on a Port
# telnet <IP or Domain> 587
Trying xxx.xxx.xxx.xxx...
telnet: Unable to connect to remote host: Connection refused
If you are getting the above response, that particular port is not listening in the server.
To Open Port For Sending Mail
Kloxo by default has Qmail as mail service..
There will not be any affect when you open a port using Iptables.
You have to open a port as like follows in a Kloxo-Qmail server.
1. Login to Kloxo as Admin user.
2. Web - Mail -Database >> Server Mail Settings
3. You can see "Additional Smtp Port" under Server Mail Settings.
4. Enter the new port number there and click 'Update' button.
You can verify whether the port is open or not by the following command.
root@localhost [~]# telnet example.com 587
Trying xxx.xxx.xxx.xxx...
Connected to example.com.
Escape character is '^]'.
220-server.example.com ESMTP Exim 4.80 #2 Fri, 12 Oct 2012 08:55:12 -0700
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.
You can use the following command to check all the LISTEN ports in the server.
Login to the server, then issue the following command
root@server [~]# netstat -ntul
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:7778 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:995 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:2087 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:587 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:110 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:783 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:143 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:1167 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:2095 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN
root@server [~]# netstat -ntul | grep 587
tcp 0 0 0.0.0.0:587 0.0.0.0:* LISTEN
tcp 0 0 :::587 :::* LISTEN
