This blog contains whatever random tech stuff I'm thinking about recently. And a lot of conference reports.

Wifi Please?

Wifi Please?

Here I am on Virgin America 29 to San Francisco, excited to be on my way to SRECon. I’ve got a 20 minute speaker slot first thing on Tuesday morning, and the last time I timed my talk it was around 21 minutes. That’s down from 45, so I’m doing pretty well, but I need to shorten it more, especially since the first session (8:30am!) might start late.

I’ve been planning to fix it on the plane, but my laptop will stubbornly not get on the wifi. So it’s debugging time.

I do the usual shuffle to turn off the proxy and hit up a url that doesn’t speak https, so the captive portal will intercept. It does, but the browser is all airborne.gogoinflight.com? Never heard of it.

Is it a browser thing? I try a shell:

$ telnet airborne.gogoinflight.com 80
telnet: could not resolve airborne.gogoinflight.com/80: 
Name or service not known

You sure?

$ dig airborne.gogoinflight.com

;; connection timed out; no servers could be reached

Bah. When I connect to a wireless network, I get an IP address using DHCP. That can set a nameserver too. How is that set, in practice? Does it update /etc/resolv.conf? I resolve (DNS joke there) to find out when I have internet access. (Later: yes it does.)

How can I get the IP of the portal? Well, I have another device, my phone. I used to have a terminal emulator on there, but I took it off a while ago when I was cleaning up apps. Once you’ve played with it for a while, it has no real purpose, right? WRONG. This would have been your moment, terminal app! Luckily for me, my phone provider gives me an hour of free wifi while flying, so I hop on there and download the first terminal app I find on the Play store.

First, ifconfig on both the phone and the laptop to compare IP addresses and see if they’re on the same network. Yes, both have 172.19.131.* addresses.

The terminal app doesn’t have the host, dig or nslookup commands installed, but I get lucky with my fourth try: ping.


$ ping airborne.gogoinflight.com
From imcp_seq=2 Packet filtered

Add that to /etc/hosts on my laptop…

$ sudo vim /etc/hosts
[...] airborne.gogoinflight.com

and back to the browser. Sorted. There’s the portal and now I can pay for wifi.

But they wanted $34 for the remainder of the flight and that’s just offensive so I ordered a beer and found other sources of entertainment instead. Wtf, Virgin America? $34?

Later that same flight:
Btw, here’s what was going on: my dhclient.conf was overriding the nameservers supplied by the DCHP server.

$ cat /etc/dhcp/dhclient.conf  
supersede domain-name-servers;

Commenting that out solved the problem. At that point, I already had the /etc/hosts workaround, but I was still on a plane with a beer and nothing much else to do. Like I said, perfect debugging time.

Conference Report: SRECon Americas 2017 Day 1

Conference Report: SRECon Americas 2017 Day 1

Bazel is easier than Makefiles

Bazel is easier than Makefiles