[Opensim-dev] User Authentication

[Frisby, Adam]

I think the 3 ping check is technically invalid. Anyone capable of capturing a packet and sniffing a session/securesession ID out of it, is quite capable of injecting our check packets in too.

Adam

From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-bounces at lists.berlios.de] On Behalf Of Diva Canto
Sent: Tuesday, 24 February 2009 9:03 PM
To: opensim-dev at lists.berlios.de
Subject: Re: [Opensim-dev] User Authentication

Mike Mazur wrote:

Hi,



On Tue, 24 Feb 2009 19:54:16 -0800

Diva Canto <diva at metaverseink.com><mailto:diva at metaverseink.com> wrote:





* Within a few days: write a simple [optional]

UserAuthenticationModule along the lines of option a) that does the

following: upon a NewUserConnection, regions will check with the

incoming user's User server that the declared user exists and is

logged into the system.





In a grid a region can be told (via a configuration option) which user

server to check. What about HG regions? How does an HG region know

which user server to ping? Is this information supplied by the

connecting client? If so, what's to prevent a malicious client from

supplying a user server that will always reply favorably?


The HG region sends that information along when the user moves away from the home UGAIM. The user carries along the collection of URLs of all of the servers it uses. It's ok if the given User Server @ foobar.com always says yes -- that's not the problem. The problem we need to detect is the user claiming to be from Intel.com or OSGrid.org, when, in fact, isn't.



Furthermore, upon AddNewClient (which happens

shortly after), regions will challenge the incoming client with 3 UDP

Ping messages having random seq numbers, to which the incoming client

must respond correctly





How does the client know the correct response?


In fiddling with the client after talking to Teravus, I discovered a pair of response-reply packets that can be initiated from the server. They are StartPingCheck / CompletePingCheck. They take a byte as argument. The server sends StartPingCheck(33), the client responds with CompletePingCheck(33). Handy.

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