Сообщение от YLess
As I said before, it computes the checksum for an array of bytes at given address in gta_sa.exe memory, so every cheat can be detected: CLEOs, s0beit, and so on. Talking about RakNet layer, when you connect to the server which calls SendClientCheck, it sends an RPC (contains address) action to the client and client also responds with the RPC (contains checksum).
It can be used like this:
SendClientCheck(playerid, 5 (iCmd), Address, Offset (relative to address), BytesCount);
and callback:
OnClientCheckResponse(playerid, iCmd, Address, checksum);