https://forum.howtoforge.com/threads/block-yandex-ahrefsbot-linkdexbot-at-server-level.76835/
Block Yandex, AhrefsBot, linkdexbot at server level? | Howtoforge - Linux Howtos and Tutorials
I have had a lot of bandwidth usage lately and checking the apache log it appears as if Yandex, AhrefsBot, linkdexbot are hitting my sites like there...