Several organizations maintain and publish free blocklists of IP addresses and URLs of systems and networks suspected in malicious activities on-line. Some of these lists have usage restrictions

 Network-wide ad blocking via your own Linux hardware
No client-side software required
Install by running one command:
curl -sSL https://install.pi-hole.net | bash

In order to block an IP on your Linux server you need to use iptables tools (administration tool for IPv4 packet filtering and NAT) and netfilter firewall. First you need to log into shell as root user. To block an IP address you need to type the iptables command as follows: