OpenDNS was one of the very first to offer a public DNS service for free with the ability to block adult websites. Previously the configuration was a pain especially for users with dynamic IP address because it requires signing up an account, setting up the filtering and then installing an updater client so that the IP address is up to date. OpenDNS have come up with a new service called FamilyShield where it is pre-configured to block pornography websites by using their DNS servers.
Preferred DNS Server: 208.67.222.123
Alternate DNS Server: 208.67.220.123
OpenDNS still offers the classic service called OpenDNS Home where you get to customize the filtering by choosing the categories that you want to allow or block and also adding individual domains to whitelist or blacklist.
Read More:
https://www.raymond.cc/blog/how-to-block-pornographic-websites-without-spending-money-on-software/