Re: From Andy:

I tried mailing this before but it bounced:

So if there was an method of giving yourself an unique IP, would 
this solve the problems?

Could use a cheapo GPS in nodes to come up with unique IPs 
based on location (which would be handy in routing too.)

Rob

> 
> I've downloaded the ISO, and had a prod at it.  Basically, it's derived 
> from a slackware distro, hence the size.  I haven't actually tied using it 
> (for lack of suitable laptop and prism card) but from looking at it I'd be 
> surprised if it does do what it says on the tin. From a 15 minute 
> inspection of the ISO image, this is what I've discovered.
> 
> A node either operates in gateway or cell/repeater mode.  The node decides 
> it's the gateway if it recieves a response to a ping from a hard-wired 
> address (an upstream IP router, ie. your ADSL router).
> 
> If it decides to become a gateway, it starts up a vtund daemon (vtun is 
> quite a nice a VPN protocol), and waits for cells to join.
> 
> If a node doesn't recieve a response to said ping, it decides to become a 
> cell/repeater.  If it associates with a gateway, it starts up a vtund 
> session with it.
> 
> Nodes randomly select a /24 network from RFC1918 space, and use allocate 
> addresses from this address space to clients.  The default IP gateway is 
> the gateway node, hence all traffic is routed via the gateway.
> 
> My opinion is that this is a brave effort, but I will happily bet any part 
> of my anatomy that this won't scale to 6000 nodes.  There are so many 
> things wrong with this approach it's difficult to know where to start, but 
> here goes:
> 
> 1) This ain't a mesh network.  Repeaters must associate directly with the 
> gateway node, and can't associate with each other.  Repeaters can't pass 
> data between themselves, and can't "chain" at all.  This limits the size of 
> the wireless "footprint", and increases the density of ISP connections that 
> you require.
> 
> 2) There's no attempt (that I can see) to ensure that IP address space is 
> non-overlapping.  Hence, it's possible for two nodes to randomly select the 
> same /24 network.  The larger the network becomes, the more likely a 
> "collision" will occur (1 in 256 for the second node, with the probability 
> doubling whenever a new node associates).  Guess what this will do to the 
> routing.  Peer to peer communication will be flaky and will get 
> progressively worse as the network grows.
> 
> 3) You can't even roam between *repeater cells* without being allocated a 
> completely different IP address.  Which may or may not be conflicting with 
> someone else, d'oh.
> 
> 4) No authentication/encryption.  Yes it says encryption on the website, 
> but the keys on the tunnels are like this:
> 	YesAtTheMomentAllEncryptionKeysAreTheSame0
> 	YesAtTheMomentAllEncryptionKeysAreTheSame1
> 	YesAtTheMomentAllEncryptionKeysAreTheSame2
> 	etc...
> 
> IMHO, this is really just a very complicated and broken system for NATing 
> an internet connection over wireless.
> 
> cheers, josh.


Bristol Consume Website: http://consume.andylaurence.co.uk/
Bristol Consume Discussion: http://consume.cyberprog.net/
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