[Opensim-dev] User Authentication

[Diva Canto]

The check ping packets are for detecting spoofing. The malicious 
man-in-the-middle already has all the info from Charles simply because 
Charles went to his region: UUID, sessionID, secureSessionID, Viewer 
EndPoint... everything that we send around to regions. Note that the 
info wasn't sniffed, it was given, as we always do. Yeah, what I'm 
talking about does not involve sophisticated equipment...
So it can easily launch an agent at WP pretending to be Charles, 
spoofing the UDP EndPoint. What it *can't* do is to *receive* the UDP 
PingCheck packets that  WP sends to that EndPoint. The best it can do is 
to send a reply guessing what the seq number might be.


Frisby, Adam wrote:
>
> 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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>
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>   

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