Internal

This is because firewalld was running

!!!ping and ssh succeed but telnet fails

Occurred while setting up an OpenShift DNS server on 172.20.2.10.

The dedicated host was clearly listening on port 53 on all interfaces/protocols, but I got:

{{{ [root@rhel-test ~]# telnet 172.20.2.10 53 Trying 172.20.2.10... telnet: connect to address 172.20.2.10: No route to host }}}

from a different machine.

Yet, ping and ssh was successful to 172.20.2.10.

{{{ [root@ns ~]# systemctl status iptables iptables.service

  Loaded: not-found (Reason: No such file or directory)
  Active: inactive (dead)

}}}

but Template:Iptables -L -n showed some activity.

The server started to answer DNS queries after I ran:

{{{ iptables -F }}}

After that, I got:

{{{ [root@ns ~]# /sbin/iptables -L -n Chain INPUT (policy ACCEPT) target prot opt source destination

Chain FORWARD (policy ACCEPT) target prot opt source destination

Chain OUTPUT (policy ACCEPT) target prot opt source destination

Chain FORWARD_IN_ZONES (0 references) target prot opt source destination

Chain FORWARD_IN_ZONES_SOURCE (0 references) target prot opt source destination

Chain FORWARD_OUT_ZONES (0 references) target prot opt source destination

Chain FORWARD_OUT_ZONES_SOURCE (0 references) target prot opt source destination

Chain FORWARD_direct (0 references) target prot opt source destination

Chain FWDI_public (0 references) target prot opt source destination

Chain FWDI_public_allow (0 references) target prot opt source destination

Chain FWDI_public_deny (0 references) target prot opt source destination

Chain FWDI_public_log (0 references) target prot opt source destination

Chain FWDO_public (0 references) target prot opt source destination

Chain FWDO_public_allow (0 references) target prot opt source destination

Chain FWDO_public_deny (0 references) target prot opt source destination

Chain FWDO_public_log (0 references) target prot opt source destination

Chain INPUT_ZONES (0 references) target prot opt source destination

Chain INPUT_ZONES_SOURCE (0 references) target prot opt source destination

Chain INPUT_direct (0 references) target prot opt source destination

Chain IN_public (0 references) target prot opt source destination

Chain IN_public_allow (0 references) target prot opt source destination

Chain IN_public_deny (0 references) target prot opt source destination

Chain IN_public_log (0 references) target prot opt source destination

Chain OUTPUT_direct (0 references) target prot opt source destination

}}}

Iptables Troubleshooting