[Moneymachine]

how can i block Ip, that is trying to hack my /rcon?

[iZN]

If the hacker is using the same IP, you can directly /rcon banip. If the hacker is using dynamic IP you can range ban like the IP starts from 192.168.*.* you can use wildcard to range ban.

[Wizzy951]

If you are talking about the console flooding, which says: Bad rcon attemp from: ip, just open server.cfg and add a line called rcon 0. If you are unfamiliar with that function, you can read there about it.