iPad/iPhone OS 3.2 DHCP issues surface

Princeton University has uncovered a serious issue with the iPad/iPhone OS 3.2.

Princeton University has uncovered a serious issue with the iPad/iPhone OS 3.2.

Here are the details:

Apple iPads began appearing on Princeton University's campus soon after they become available April 3 2010. On April 4, we observed our first DHCP client malfunction from an iPad. Over the next few days, additional iPads malfunctioned in the same way.

The malfunction we see is that the iPad uses DHCP to obtain a lease, renews the lease zero or more times (as expected), but then continues using the IP address without renewing the lease further. The iPad allows the DHCP lease to expire, but it continues using the IP address after allowing the lease to expire. The incident continues for some time (typically hours); usually it ends when the iPad asks for a new DHCP lease, or the iPad disconnects from the network.

The iPad owner is often unaware of any problem, Nevertheless, it is an issue because it can interfere with service to other devices. Once the iPad has allowed its DHCP lease to expire, the DHCP server may lease the same IP address to another client.

Princeton is taking the steps of blocking devices that misbehave in this way:

When a DHCP client malfunctions this way repeatedly, Princeton blocks the device from using those campus network services which rely on the device's DHCP client respecting lease times. These include our wireless services. We do this to protect other customers of those services from the disruptions caused by the malfunctioning devices.

And the problem is widespread:

As of April 15, 22 of the 41 iPads on the campus network have exhibited this malfunction. Some have malfunctioned in this way several times; eight devices have been blocked.

This isn't the only networking issue that the iPad is suffering from.

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