As you know, packets have a payload descriptor so you can check to see what kind of package we are dealing with. So when I encounter a packet with an invalid descriptor (other than 0x00, 0x01, 0x80, 0x81 or 0x40) I assume for one reason or another the stream lost sync and I drop the connection. However, This occurs quite a lot, and I don't actually have the feeling that I'm loosing sync, but I think it are custom codes from other clients.
Could this be? If so, can I get a list of these custom codes (the known ones) somewhere so I can ignore the packet if it's one of these, and drop the connection if it is still another.