For those who are annoyed at clicking at one thing, only to end up twitter – https://twitter.com/ErrataRob

Inflight wifi didn’t work so of course I had to debug it. It appears the problem is lack of DHCP lease. The WiFi was using 8 hour leases, which was time enough for many planeloads of passengers to embark/disembark.

A quick ARP scan at the time showed there were 55 devices on the network, almost entirely mobile devices (which randomize their MAC addresses, whereas laptops don’t).

Given the number of takeoffs and landings in the 8 hour period, the lease table can easily fill up.

The fun fact about DHCP is that when this condition happens, it sends no response to the client. In other words, when trying to diagnose why " the wifi isn’t working", there’s no difference between this cause and half a dozen other causes.

I have to guess this is the cause simply by looking at the fact lots of other people seem to have successfully gotten a DHCP response but I haven’t.

I told the flight attendant “the WiFi isn’t working”. She then “reset the Internet”, after which I could get a lease. Apparently in the front near the entrance/exit, there’s a button simply labeled “INTERNET RESET” that she presses whenever a customer complains.

Obviously, one solution to the problem is that DHCP leases on planes should be drastically shorter, like at 1 hour intervals. Secondly, the number of leases should be drastically increased.

ha. been there, done that. they do have it locked down pretty well though (i couldnt achieve external traffic to my personal dns) i was surprised at the lack of guest isolation (on delta oh 3 years ago now)

8h lease might honestly be better, in the case where you have medium haul international flights with wifi, or a shorter flight with delays causing people to be onboard for longer…

If you are delayed you don’t want to be inundated with “the wiffy isn’t working” while dealing with 100 other complaints, whereas when things are smooth the “reset internet” will do just fine.