Portmapper also known as rpcbind is a service of UNIX and Linux which assists in mapping remote procedure call to network. Its primary work is to mount directory over a network. Attacker sometime use open portmapper to exploit DDOS attack.
stop command is
sudo systemctl stop rpcbind
systemctl stop rpcbind.socket
disable after restart the server also
sudo systemctl disable rpcbind
check the status of rpcbind
sudo systemctl status rpcbind
You can also bind the ip address because some time need it to transfer nfs
sudo iptables -A INPUT -p tcp --dport 111 -s <trusted_ip> -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 111 -j DROP
