Wednesday, February 18, 2009

Ad-Hoc Networks

There have been a few questions about Ad-Hoc networks over time. They simply can't work as it stands. It is not a simple matter of adding the network to the card, or forcing it to be detected.

For one thing, the cards can not be configured to use a static IP address. So there at least needs to be a DHCP server out there on the network somewhere. If someone really, really needs to do this, I would simply suggest a portable and battery-powered access point such as this one.

6 comments:

WeshaTheLeopard said...

I'm afraid the card must always phone home in order to start working (and I'm yet to test if firewalling it out doesn't break things), so ad-hoc network might not be useful anyways...

Dave Hansen said...

The card does not need to phone home to function, except at first to retrieve settings. After that, it can perform the "Upload to PC" function with no Internet connection at all.

WeshaTheLeopard said...

OK, so I firewalled the card to ONLY talk to my server and no other computer on the network, and it works just fine. Once again kudos to you and to Jeffrey Tchang for the standalone server! I think I should port it to some other language, too.

hacker said...

WeshaTheLeopard, you might be interested in this, perhaps - http://kin.klever.net/iii/ - it's pretty basic implementation, but does the trick and doesn't take up much memory.

Guillaume Filion said...

Actually, there's a way of assigning IP addresses when there's no DHCP server around. It's called the link-local subnet (http://www.ietf.org/rfc/rfc3927.txt).

Basically, the card should assign itself an ip in the 169.254/16 prefix. If there's another PC in the same (ad-hoc) network, it will have assigned itself an ip in that prefix too, so they should be able to discover each other with the standard local discovery protocols (SMB or Bonjour).

Since the Eye-Fi Manager runs on Windows, I guess that it uses SMS, so installing Samba on the linux server should do the trick. BTW, it's all speculation, since I don't have a eye-fi card, but technically there's no reason why it shouldn't work.

john s said...

checkout zeroconf: http://www.zeroconf.org/

avahi implements it on linux.

very similar to the link local stuff mentioned above