[Mean]

pawn Код:

public OnRconLoginAttempt( ip[ ], password[ ], success ) { 
    if( strcmp( ip, "youriphere", true ) ) {
        SendClientMessage( playerid, -1, "Only the owner can log into the RCON! " );
        success = 0;
    }
    return 1;
}

Untested, should work.