[Mongrel]

The source code is all there. It's easy to write a few lines so that world.exe only allows specific accounts to log on.

Something like:

world/client.cpp:

case OP_SendLoginInfo:

char name[19] = {0};
char password[16] = {0};

strncpy(name, (char*)app->pBuffer, 18);

if ((!strcmp(name, "goodfriend1")) || (!strcmp(name, "goodfriend2")))
   cout << "Legit account logged on " << name  << endl;
else
{
   cout << "Invalid account detected: " << name << endl;
   ret = false;
   break;
}

Of course, it would be better to write a function that checks a database or ini file for legit accounts