4 ms·

Universities Ban iPads

8 points by edw519 17y ago

iamwil 17y ago
Hey, you're back submitting articles.
ugh 17y ago
This is about the WiFi issues, not any other reason (like “Students really shouldn’t use closed toys like that” or something :)
Confusion 17y ago
The article isn't very good. Things like Princeton said the iPad causes DHCP client malfunctions are nonsensical. There is not a clue in the article as to the real problem. I suppose the iPad could be very agressive in its attempts to obtain a DHCP address and cause DHCP server problems, but other than that...?
- jarek 17y ago
  Technically speaking the quoted sentence fragment might be correct: other machines on the network are DHCP clients, and an IP address collision (caused by the iPad's DHCP fail) can lead to them behaving in a way that would be described as a malfunction. That being said, yeah. Not very good. It's a mainstream media article, we'd be waiting for a long while if we wanted them to make sense of technology beyond "ooh, shiny."
- fhars 17y ago
  The problem is that it keeps using an IP address after the lease has run out and the address may have been given out to another device. The difference between universities that see this problem and those that don't is probably that the latter assign the addresses for WLAN clients from a large pool (try 10.0.0.0/8) that allows them to keep the association between mac address and IP address for the whole term or even longer.
- jimfl 17y ago
  From my understanding, the iPad continues to use the IP address after the DHCP lease is expired, which could cause other clients assigned that address to be confused.
ggchappell 17y ago
I've seen several articles on this phenomenon, but none of them seem to address the real issue. I understand that banning the iPad from a network may be necessary in the short term. But over the longer term, if single device can wreck your network just by using an address for a bit too long, then there is something wrong with your network. I'm still waiting for the headline that says, "Security hole found in DHCP[1]; iPad accidentally exploits it". Hasn't happened yet. Why not? [1] Or wherever the root problem turns out to be.
- hga 17y ago
  It doesn't "wreck your network", rather, when it keeps its DHCP lease beyond the allowed time (due to being in "screen off" mode during the expiration) it wrecks things for itself and whomever is unlucky enough to have gotten reassigned the same IP address. Not a security hole, just a "doesn't play well with others", and I can't think of a way to avoid this without going outside of DHCP (e.g. assuming bad behavior and therefore using a big enough pool and not reassigning IP addresses for a long time).

8 points by edw519 17y ago

Hey, you're back submitting articles.

ugh 17y ago

This is about the WiFi issues, not any other reason (like “Students really shouldn’t use closed toys like that” or something :)

Confusion 17y ago

The article isn't very good. Things like Princeton said the iPad causes DHCP client malfunctions are nonsensical. There is not a clue in the article as to the real problem. I suppose the iPad could be very agressive in its attempts to obtain a DHCP address and cause DHCP server problems, but other than that...?

jarek 17y ago
Technically speaking the quoted sentence fragment might be correct: other machines on the network are DHCP clients, and an IP address collision (caused by the iPad's DHCP fail) can lead to them behaving in a way that would be described as a malfunction. That being said, yeah. Not very good. It's a mainstream media article, we'd be waiting for a long while if we wanted them to make sense of technology beyond "ooh, shiny."
fhars 17y ago
The problem is that it keeps using an IP address after the lease has run out and the address may have been given out to another device. The difference between universities that see this problem and those that don't is probably that the latter assign the addresses for WLAN clients from a large pool (try 10.0.0.0/8) that allows them to keep the association between mac address and IP address for the whole term or even longer.
jimfl 17y ago
From my understanding, the iPad continues to use the IP address after the DHCP lease is expired, which could cause other clients assigned that address to be confused.

ggchappell 17y ago

I've seen several articles on this phenomenon, but none of them seem to address the real issue. I understand that banning the iPad from a network may be necessary in the short term. But over the longer term, if single device can wreck your network just by using an address for a bit too long, then there is something wrong with your network. I'm still waiting for the headline that says, "Security hole found in DHCP[1]; iPad accidentally exploits it". Hasn't happened yet. Why not? [1] Or wherever the root problem turns out to be.

hga 17y ago
It doesn't "wreck your network", rather, when it keeps its DHCP lease beyond the allowed time (due to being in "screen off" mode during the expiration) it wrecks things for itself and whomever is unlucky enough to have gotten reassigned the same IP address. Not a security hole, just a "doesn't play well with others", and I can't think of a way to avoid this without going outside of DHCP (e.g. assuming bad behavior and therefore using a big enough pool and not reassigning IP addresses for a long time).