[CS-FSLUG] wireless network in a disaster?

Marco Tedaldi marco.tedaldi at gmx.ch
Tue May 5 01:52:29 CDT 2009

Ron Thompson schrieb:
> A question came to mind and your the best pool of expertise I know.
> Before posing the question I'll set up a fictional situation.
> A disaster is occurring, or has recently occurred.  In the disaster power is 
> out and most or all of the ISPs are also out.  Other modes of communication 
> such as telephone or cellphones are also out of service or operating at a 
> reduced capacity.
Yeah, this is quite a problem. Phone-Systems should have backup power
for at least a few hours. but it might well be that your phone at home
does not work without external power from the wall socket.

> Randomly scattered over the area are personal laptops, with a few hours of 
> battery capacity, that have wireless network capability.
Nice Idea...

> While cellphone services are the exclusive domain of private enterprise, 
> personal networks are not.

> The question is: Is it possible to set up an open wireless router in such a 
> way that anyone who finds it could communicate to the host computer?   The 
> internet isn't available so normal e-mail isn't available.
It is technically possible to make a network out of scattered nodes.
What you want here is a so called mesh-netwerk, where the nodes forward
the data packets for each other to the target.
OLSR and B.A.T.M.A.N. might do what you are looking for. But keep in
mind that laptops generally have quite limited range (maybe 50m) while
dedicated routers (like the famous linux router Linksys WRT54GL) give
quite a bit more range.

What would have to be done:
All the participating devices must have OLSR or BATMAN installed and
configured (given a unique IP) and enought of them must be online to
form a mesh. All this should be done before the desaster.

If you stick to routers you're on the good side. A WRT54GL should run on
a simple car battery for about a week. And you can connect to such a
router with almost every Wifi capable device. You might want to take a
look at the freifunk.net project.

OLPC on the other hand has another interesting approach for mesh
networks directly from the end node.

I hope I could help a bit. Just ask again if there are more questions :-)

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