In order to talk to each other, the client and the server need to agree on a set of ID numbers -- opcodes -- that define what each packet does. For example, maybe opcode 1234 is for spawn packets, 1235 is the client telling the server that it targeted something, 1236 the server telling the client they took damage, and so on.
This is all well and good, and in the early days the server and client used a static set of opcodes, so the numbers never changed. But EQ's networking was designed in the early days of online gaming... back when developers were still naive enough to implicitly trust the client. So as a result, the client was made practically omniscient -- it is given way too much information about where every mob in the zone is at all times, for example, and, especially early on, the server gave it too much control over things like its current position, blindly trusting that it would never decide to lie about where it was and instantly warp across the zone. So hacking tools started to surface.
By the time the developers thought to address this, they must have decided it was too late to radically change the way the client worked to make it less absurdly exploitable. So they started to do one of the most basic and seriously inadequate things they could... they started scrambling the opcodes the client and server used to talk to each other, every time there was a new patch. That way, hackers would have to figure things out all over again. Not a very effective deterrent, since the hackers could quickly re-identify a lot of things just based on what the packet data looked like, or when it was sent out (no surprise that the packet the client sends when you target something is the targeting packet). But it at least made them focus on finding the opcodes for the most exploitable packets after every patch, rather than having a near-complete understanding of what the client was doing at all times, I guess...
tl;dr: you need to have the exact patch that was baked into the client on the Titanium CDs to be able to communicate with the p99 server at all; otherwise the opcodes won't match up, and the server and client will both see what the other is trying to say as gibberish. The only reason Titanium works is that people from the EQEmu community did a lot of packet capturing when Titanium was brand new and its patch was still current, to map out as many of its opcodes as they could. Trying to go back and figure out the opcodes for arbitrary client versions off of other CDs would simply not be worth the effort.
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01-08-2017, 01:45 PM
Linear Mode
