Port 111
 

I will like to know what port 111 is used for, how to know if it is open, how to open it and how to close it.

The port 111 is normally used by the RCP port mapping process. You can check if is open with netstat and close by stopping the process who binds that port.

From /etc/services

Something has to listen for it (rpcbind?). The firewall has to allow it (iptables / netfilter). You can check if it's active or listened for with netstat. And probe for it from outside the network with nmap / nagios.

You might find this list of ports interesting: https://en.wikipedia.org/wiki/List_o...P_port_numbers

You can close and open a port on a firewall.

Firewall can be a hardware or software depends on how it is implemented in your system or network.

You can also kill the process that uses the port but if the port is unused it is a good practice to close it on the firewall.

Check out this link, it has a good info: https://superuser.com/questions/1278...om-commandline

The most common use I've seen of port 111 is with nfs (v2, v3) https://www.centos.org/docs/5/html/D...y-portmap.html

And of course, never make any such port available "to the outside world." :tisk:

If you need to channel the traffic through the Internet, always use an OpenVPN tunnel, properly secured with one-of-a-kind digital certificates and tls-auth. The port-mapper and all other daemons should be listening only to the virtual IP-addresses created by the OpenVPN software-router, and be communicating with their peers only through the tunnel. Direct access (going and coming) should be blocked by firewalls.