https://community.bistudio.com/wiki/Arma_3_Dedicated_Server#Instructions_.28Linux_o.2Fs.29

Ensure you have downloaded the latest plugin and got your server alive.cfg file from War Room (follow the instructions on the server setup page)

http://www.alivemod.com/forum/conversation/post/10705

also http://www.alivemod.com/forum/1425-there-is-a-problem-with-the-alive-plugin-solved

Recommend that your arma 3 instance is restarted before starting a mission. We've seen issues with threading when a server is left on for a long time.

If you are running CentOS 6 there is a special build here http://alivemod.com/downloads/ALiVEPlugIn.so_CENTOS_6 thanks to @Frost