Probably they are checking the userinfo string on connection through LUA. To be honest I just feel it's spam if you don't run PB on your server and if you do then players with PB disabled would be auto kicked. I would suggest to use g_silentac 2 for anti cheat protection and silEnT mod auto generates key for users to store XP and other admin features. If you still require that feature then I would suggest to contact that server admin and ask him if he would like to share that LUA or not.