GreenLife Emerald Viewer client detection??

I've been experimenting with alternative Second Life clients and I have to say GreenLife Emerald Viewer gets my vote.
Not only does it contain several enhancements over the official Linden Lab's viewer it's the only software which runs flawless on my old unsupported ATI MOBILITY RADEON 7000 IGP laptop.

Anyway this program has a built-in avatar scanner and can also detect the presence of other Emerald clients, a good idea maybe but it's not possible to disable the transmission of client information.

Does anyone know how client information is transmitted or detected, I suspect it uses a special hidden channel because detection can only be achieved from within a set distance from the user.

I'd never heard of that viewer until your post. You might try asking LodgGregGreg Back in SL, or try the other means of support listed at http://modularsystems.sl/index.php?option=com_content&view=article&id=5&Itemid=10 . Maybe someone reading this can read the source code, which can be obtained at http://modularsystems.sl/index.php?option=com_phocadownload&view=category&id=2:sourcecode&Itemid=5 , and answer your question.

If I had to guess, I'd guess that your viewer has a built-in HUD (the avatar scanner), and part of the script also queries agents in range [llSay()] over a private channel. If another script is listening on that channel and recognizes the query, it answers back, and it can be assumed to be the built-in HUD in another copy of the viewer.

I recently downloaded the GreenLife viewer and played around with it, and I love it! If one could build a viewer that had the featuresets from both GreenLife and CoolSL, it would be THE ultimate viewer!

Anyways, I paid close attention to the client-reporting features. It seems that I was pretty much spot-on with my analysis above except with the communication. Rather than using llSay, it is likely using llShout, since any avatar beyond 100m is reported as "out of range".

Another probability, given GLE's ability to detect avatars sim-wide as well as retrieve UUID keys for each avatar, is that the GLE viewer has the ability to directly query the sim server itself. However, a caveat to the client-detection in the documentation states that the viewer only reports viewers that are compatible with its query method, so standard LSL methods and channels are still the most likely method.

It's being done with texture hackery, an extra one is tacked onto the avatar when you use one of the identifiable viewers, and the UUID is used as the client ID.