Lookst like firewalld is not opening port 25. I tried adding the smtp service, and port 25 separately as well, yet, I am unable to telnet to the server. Any tips?

[root@host ~]# firewall-cmd --zone=public --list-all
public (default, active)
  interfaces: eth0
  services: dhcpv6-client http https smtp ssh
  ports: 3762/tcp 25/tcp 7683/tcp 4424/tcp
  masquerade: no
  rich rules:

[root@host ~]# nmap XXXXXXXMYIP

Starting Nmap 6.40 ( http://nmap.org ) at 2016-01-14 00:11 CET
Nmap scan report for CentOS-72-64-minimal (XXXMYIP)
Host is up (0.0000080s latency).
Not shown: 990 closed ports
21/tcp    open  ftp
53/tcp    open  domain
80/tcp    open  http
110/tcp   open  pop3
143/tcp   open  imap
443/tcp   open  https
993/tcp   open  imaps
995/tcp   open  pop3s
3306/tcp  open  mysql
20000/tcp open  dnp

Nmap done: 1 IP address (1 host up) scanned in 0.05 seconds
[root@host ~]#
  • 1
    First, start a service that listens on port 25. – Michael Hampton Jan 13 '16 at 23:16
  • Phew that was it. Postfix inet interfaces was set to localhsot and changed it to all. This also helped serverfault.com/questions/371713/… – giorgio79 Jan 13 '16 at 23:22
  • 1
    Don't forget to forbid open anonymous relaying! – Anubioz Jan 13 '16 at 23:23

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