doing some ICQ research and I found that LICQ's homepage is still online, with zero hint that it hasn't been updated in 11 years:

[foone@digipres.club]

a senior project about v5, which has some info:
http://www.carfield.com.hk/document/networking/icq_protocol.html

[foone@digipres.club]

well ICQ99 seems to work on windows 10, so that's good. Sadly I can't register my ICQ number.

[foone@digipres.club]

fun fact about this era of the ICQ protocol: It's apparently entirely UDP based, and I think it does UDP directly between users as well, rather than the server.

In other words, it's exactly the kind of internet program that only made sense in 1996-1999 before NAT was a widespread thing

[ddlyh@topspicy.social]

@foone
... Are you planning to relaunch ICQ with a new server as a service for anyone who still has a client??

[foone@digipres.club]

@ddlyh thinking about it yeah. specifically for the 1999-2000 clients, before it became AIM-flavored

[foone@digipres.club]

their were proxies almost immediately, which used a local program that talked over HTTP to a remote server that then did UDP to the target (or their proxy) because any NAT, firewall, or proxy situation completely broke this

[foone@digipres.club]

why doesn't my "gaming laptop" have wireshark already installed. this system is barely usable

[sun@shitposter.world]

@foone it used a centralized server for identity and finding clients and then established a direct p2p connection between clients (that could be trivially spoofed)

[feld@friedcheese.us]

@sun @foone When did ICQ and AIM end up being the same protocol? (OSCAR)

[foone@digipres.club]

a computer needs a hex editor, packet capture, Good text editor, SSH client, ghidra or ida, decompilers for C# and java, C compiler, pythons (2 and 3), binxelview, Dependencies viewer, DOSBox, UNP, at least one unity unpacker, debugger, relative-searcher, yychr, and emulators for at least 12 consoles & home computers.

otherwise it's just a toy, like a Nintendo.

[foone@digipres.club]

@feld @[email protected] I think in the 2001 release? but I can't find details.

[foone@digipres.club]

hmm, I'm using ICQ 99b and it seems to be sending version 5 packets? interesting

[foone@digipres.club]

packets are encrypted which is a Pain.the encryption is trivially breakable but it means I can't use wireshark to see the packet contents.

unless I add support to wireshark, which sounds like A Project in itself

[ericgus@mastodon.social]

@foone Well if you are going down a rabbit hole, why not see how far down it goes.. ?

[foone@digipres.club]

@ericgus I'm already going down too many of those!

[foone@digipres.club]

oh I can write lua (eww, for low level binary stuff?) dissectors. that'll make this slightly easier

[foone@digipres.club]

I'm gonna write python code to decode a packet from these docs and then I'll convert that to lua. writing it in lua the first time will be too painful, when I don't fully understand how this nonsense works

[foo@fosstodon.org]

@foone If it helps for reference, I once wrote a Wireshark lua dissector for 2ping, a low-level UDP binary protocol. Though as a warning, I haven't looked at it in about a decade, so it may not even work anymore.
https://github.com/rfinnie/2ping/tree/main/wireshark

[sundrop@gelatino.us]

@[email protected] @[email protected] is it strictly a proprietary archival protocol or is there a daemon available for it?

[foone@digipres.club]

@Sundrop @ericgus there's no daemon for this version, no