Unique Client Identifier
 

Is there an identifier that is sent when a client logs into the server?

Client 1 gets id = 1
Client 2 gets ID = 2

These would be determined directly by a client, kind of like windows GUIDs or SYSIDs.

Just trying to learn deeper.

We identify based on opcodes we get sent (and the size of the packet).

Connecting to world we check OP_SendLoginInfo and zone OP_ZoneEntry.

So on that note.

When a client connects, is there a unique identifier that ties that client to that machine?

No, there is not in any of our clients.

To implement such a change would require a clientsided hook that detects multiple logins from the same PC based on various factors like P99 does.

There is on live (now)

Check my Facebook and text me, I got banned.

To add to what demonstar55 posted, SoF and SoD share common opcodes for initial contact..which is why they are sent to different ports (5998 vs. 5999)