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Exploring the Halo 1 System Link Protocol

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Re: Exploring the Halo 1 System Link Protocol

#41

Post by bradfox2 »

nhellman wrote: post #16
cglong wrote: post #13

It's a shame it's proprietary, but there's a neat service[1] that's been around for over a decade that reverse engineered System Link and similar protocols to make them Internet-enabled. [1]: https://www.teamxlink.co.uk/

I haven't tried this out, I wonder how well the Halo 1 net protocol works over a less reliable connection. I encounter issues as soon as I momentarily minimize the emulator and it does not recover without starting a new game. I wonder if it is enough for XLink to simply send the packets through a networked tunnel or if it actually needs to modify the packet payload somehow. The consoles might be able to handle everyt…

I played competitive HaloCE through 3 at a professional level. XBConnect is what people playing competitive CE used prior to halo 2 and xbox live. Game was playable up to about 60ms, with The same advantage existed on LAN, with competitive tournaments setup to trade host advantage for team color advantage. The last in person CE lan I attended, we were playing on modded Xboxes with a patched version of the game that allowed a third box as a neutral host, and added an on screen timer. Happy to expand on the details if anyone is interested.

Re: Exploring the Halo 1 System Link Protocol

#42

Post by bradfox2 »

dinartem wrote: post #30

Nice work! Always fun to see something I wrote long ago reverse engineered. The packet format was indeed inspired by ESP over UDP, and I named it XSP. After system link shipped with the original launch of the console, I also worked on Xbox Live networking, including the client/server interactions and the design and implementation of the front-end Security Gateways that all Xboxes would talk to, first to authenticate…

Have you ever connected with the folks behind XBConnect?

Re: Exploring the Halo 1 System Link Protocol

#43

Post by monocasa »

dinartem wrote: post #32
monocasa wrote: post #31

Earlier quoted context omitted.

Nice! You did a great job on the protocol. Probably my only complaint on the XSP side of things is the fact that you have to do relatively complex parsing of the XSP packets before you can get to the point of verifying the signature of the packet. Seems like all of the corner cases were handled well in the implementation on the boxes, but as someone who does auth/cryptography in my day job, it kind of gives me the he…

That's a valid point about complex parsing. I remember being very concerned about adding unnecessary overhead to each packet during encapsulation. As for the SG, it primarily authenticated the Xbox machine account using Kerberos and then maintained a security association, accepted heartbeats, authenticated and decrypted incoming ESP-UDP packets into IP packets that it forwarded to the backend servers. Responses from…

Ok, cool. That's about what I figured at this point. Originally while REing the protocol I thought that it was holistically handling auth at that XSP layer, but then was surprised when a box would the identify it's XID to matchmaking as well, which should have been stored in the krb ticket to bootstrap that connection.

Thanks so much, I really appreciate your candor here!

Re: Exploring the Halo 1 System Link Protocol

#44

Post by k8svet »

Halo 1 + system link + XBConnect is responsible for a huge swath of my career, life, friendships. I remember sitting in my parents basement as a [very young person] marveling at XBC and wondering how it worked. I can still remember the layout of the webpage I found diving into the protocol, how discovery worked, broadcasting discovery packets to 0.0.0.1. I remember opening Ethereal and seeing the packets. I remember, a bit later, hacking together a Java app, failing at a C++ app, many years later trying one in Go and then... pre-drop-@-gc Rust. Wonder if instead of encapsulating packets with src/dst mac I could send a map back and forth and index into it to save the whole... 6 bytes?

So many hours of my life spent playing that game. Even recently I re-discovered an old Halo (x)ISO I mastered in high school containing a multitude of map packs that the community had made for it (NMP, NMPv2, CXE, +??). I even hacked them to change their internal map IDs to prevent cache conflicts when switching packs. My friend dug it out of his collection, copied the ISO and I fired it up in XEMU. Wild to see some of those maps, that some random people made with hacked together tools, and wild to read this now, and the comment from /u/dinartem. Even wilder that it's playable emulatable now. Especially given the way MCC massacred Halo1 with the horrendous Halo 1 PC port back to Xbox, and then later to PC again.

I'm horrified to see someone comment that multiplayer almost didn't launch with Halo 1. My life would be so unimaginably different.

So many memories, this comment doesn't mean much, but what a thing to see on HN.

lol, I'm almost tempted to drop my XBConnect Forum name here. I remember when I thought Todd was an absolute god among humans. Oh man, thank you HN for the dose of nostalgia. If anyone remembers a huge block-letter forum signature that was briefly animated ;). The era of sprawling PHP file upload sites. Wow. The internet before it became truly cursed.

edit: shout out if anyone knows what I mean by "clear walls". Oh man, what a world.

editN: oh wow, "cross over cables" is a phrase I haven't thought of in a long time.

editLast: there was a glitch that was supposedly reproducible that caused a tertiary console's player to override the inputs of another console player. Afaik it was never widely discussed, despite repeated claims that it was reproducible on demand. If anyone has any details, you'd make this a truly magical thread for me. <3.

Re: Exploring the Halo 1 System Link Protocol

#45

Post by k8svet »

willis936 wrote: post #34
monocasa wrote: post #25

Earlier quoted context omitted.

From what I've heard from microsofties over beers, it was really the second one. They didn't expect developers to write network code in ~2001 that didn't have memory safety vulnerabilities and wanted a barrier there between simple overflows and system security.

The child in me from 20 years ago dreams of a software tool downloaded from a questionable website that jailbroke an xbox just by putting in the IP address.

I mean, minus the USB->controller wire "hardware mod", it has been perfected to "download a memory card gamesave", "have a non-GOTY edition of a game" and you were a few minutes away from being soft-modded, ready to hack your cached Halo maps to swap the needler texture in for the wall textures, and change character textures to brighter versions (gummibear hack, maybe?).

Makes me want to wipe the XBMC xbox in my parents basement and break out my Splinter Cell and memory card just to do it all again.

Re: Exploring the Halo 1 System Link Protocol

#46

Post by k8svet »

bradfox2 wrote: post #41
nhellman wrote: post #16

Earlier quoted context omitted.

I haven't tried this out, I wonder how well the Halo 1 net protocol works over a less reliable connection. I encounter issues as soon as I momentarily minimize the emulator and it does not recover without starting a new game. I wonder if it is enough for XLink to simply send the packets through a networked tunnel or if it actually needs to modify the packet payload somehow. The consoles might be able to handle everyt…

I played competitive HaloCE through 3 at a professional level. XBConnect is what people playing competitive CE used prior to halo 2 and xbox live. Game was playable up to about 60ms, with The same advantage existed on LAN, with competitive tournaments setup to trade host advantage for team color advantage. The last in person CE lan I attended, we were playing on modded Xboxes with a patched version of the game that a…

Maybe you're aware but... https://halo1nhe.com/

Shout out the {Halo 1 Hub, xemu, Halo Modding Reclaimers, Invaer} Discord members. I'm sure some of you in this thread are already there. :D

Re: Exploring the Halo 1 System Link Protocol

#48

Post by networkchad »

dinartem wrote: post #30

Nice work! Always fun to see something I wrote long ago reverse engineered. The packet format was indeed inspired by ESP over UDP, and I named it XSP. After system link shipped with the original launch of the console, I also worked on Xbox Live networking, including the client/server interactions and the design and implementation of the front-end Security Gateways that all Xboxes would talk to, first to authenticate…

Thanks for all your hard work. Many a hours (days?) of entertainment amongst my friends were possible due to it :-)

Re: Exploring the Halo 1 System Link Protocol

#49

Post by bradfox2 »

k8svet wrote: post #46
bradfox2 wrote: post #41

Earlier quoted context omitted.

I played competitive HaloCE through 3 at a professional level. XBConnect is what people playing competitive CE used prior to halo 2 and xbox live. Game was playable up to about 60ms, with The same advantage existed on LAN, with competitive tournaments setup to trade host advantage for team color advantage. The last in person CE lan I attended, we were playing on modded Xboxes with a patched version of the game that a…

Maybe you're aware but... https://halo1nhe.com/ Shout out the {Halo 1 Hub, xemu, Halo Modding Reclaimers, Invaer} Discord members. I'm sure some of you in this thread are already there. :D

Someone else had the boxes, but that is what we were using!

Re: Exploring the Halo 1 System Link Protocol

#50

Post by burnsaga »

Huge fan of Halo 1, and for me, the original (via LAN, XLAN or Xlink Kai) is still the preferred way to play compared to Halo MCC (RIP XBconnect). I dabble in map mods so this is mostly over my head, but interesting read. Don't know if would help your research: but are you aware of a mod/mappack called Halo 1: NHE (No Host Edition)? It's a hacky way of using a third box to host the system link game.

http://halo1nhe.com/

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