February 9, 2006 2:51 PM   Subscribe

I sometimes have networks show up on my iBook's wi-fi indicator, and then I can seemingly 'join' those networks without entering a password. But then I open my browser and it won't call anything up. Are these phantom networks? Or do I need to play around with the settings? Similarly, I get 'computer to computer networks' that show up all the time, and those never enable web surfing. Is there some way to jump on those? What's the use of a network if you can't use it, after all?
posted by jgballard to Computers & Internet (10 answers total)
All you're doing is associating with the Access Point. In order to surf, you'd also need to be given or assign yourself a valid IP address. Beyond that, if there's a hardware address whitelist, you must be on that. Hope that clears things up.
posted by cellphone at 3:00 PM on February 9, 2006

Well, for one, network does not equal internet. So maybe your connecting to a network that's not connect to the internet (which does seem a bit unlikely these days).

Maybe the network isn't set up for DHCP? Or it might need an address for DHCP.
posted by doctor_negative at 3:02 PM on February 9, 2006

Though it's unlikely in a neighborhood setting, you could also be connecting to networks that don't have access to the internet. When you're assigned IP address settings by the network, look at what you get for Default Gateway in the Network Settings. Then try going to http://defaultgateway and see if you get asked for login information from the router.

If you do, you've successfully connected to the network and can communicate with the router. There's no reason the router has to forward your requests to the internet, or even that it's set up to do so, though.
posted by odinsdream at 3:05 PM on February 9, 2006

Does the iBook allow you to distinguish between computer-to-computer (ad hoc) networks and access point networks? I know if I'm in a classroom full of laptops, I can see several ad-hoc networks, but none of them would be able to give me an internet connection.
posted by stopgap at 3:11 PM on February 9, 2006

As an example...

At home I have my wireless network completely open, the server gives out IP addresses and the DNS server will resolve your requests. But that's as far as you get, my firewall won't forward your packets out to the internet. In order to actually do anything, you have to connect via VPN and login (I use Microsoft's PPTP/MPPE).

Complicated for a home network, I know, but this is also a pretty common setup at the university I work for (UIUC). I can think of three different wireless network systems on campus that work this way, but with different VPN solutions (Cisco, PPTP, and Enterprise WPA).
posted by sbutler at 3:23 PM on February 9, 2006

a network that's not connect to the internet (which does seem a bit unlikely these days).

Seems very likely to me. Perhaps someone has left the wireless router switched on, but shut off their computer, or disconnected it from the internet. Perhaps even they use a dial-up connection (horror!) in which case it's almost certain to be disconnected most of the time.
posted by sfenders at 4:28 PM on February 9, 2006

most ad-hoc networks I see are offline, because they're the bottom priority default of some off the shelf laptop wireless setting that the user has never used/changed/touched. So yeah, you could probably enable filesharing or look around the hard way but odds are you're not going to get anywhere.
posted by tiamat at 4:52 PM on February 9, 2006

Does the iBook allow you to distinguish between computer-to-computer (ad hoc) networks and access point networks?

Yes, OS X allows you to see if it is an ad hoc network by the change in icon on the menu bar (if enabled).
posted by qwip at 5:06 PM on February 9, 2006

From my experience in the past (note: this is PC related experience), if a wireless router is set up to do MAC address filtering (ie only certain MAC addresses can use the router) and no other security (WEP, etc), then even if you aren't in the MAC address whitelist, you can still connect to the router. However, it won't grant you an IP address, and I'm pretty sure even if you hardcode an IP address it still won't accept your packets.
posted by antifuse at 2:47 AM on February 10, 2006

Manually assign yourself an IP address and see how that goes. If you are savvy enough, you can run a packet sniffer to see what kind of traffic goes on there. Also, I've had at least one experience where a client was wirelessly connecting to his router with the wrong WEP password. He would connect, but without DHCP or any communication.

Also ad-hoc networks shouldn't have internet access anyway; they are direct connections among computers, with no gateway/router. If one peer had two NICs, it could function as a gateway... but that is far beyond the scope of an average user.
posted by adzm at 4:38 AM on February 10, 2006

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