This was originally posted on 2010-04-17 to http://andrewho.co.uk/weblog/opendns-and-bt-openzone
I frequently work in coffee shops, and if I happen to have forgotten to bring my Vodafone USB modem I use the free WiFi, which is run by BT Openzone. Now, I like to use OpenDNS, particularly when I'm not at home. It's significanly faster than both the BT Openzone servers and the Vodafone ones, so it really does make a difference whilst browsing.
The only problem is that in order to login to BT Openzone, you have to visit the
domains www.btopenzone.com and my.btopenzone.com which, if you're connecting
from a BT Openzone hotspot, have different A records compared to what everyone
else thinks they resolve to. This is distributed through the nameservers they
supply to you via DHCP when you connect to the wireless network. So connecting
used to be a rigmarole of removing my custom nameservers, connecting, and then
putting them back. This takes quite a while on a slow laptop (plus requires
authentication three times). The solution to this turns out to be rather
simple: just put the special A records in /etc/hosts. I'm unlikely to want to
connect to those domains outside of their WiFi. To save you from having to
query the DNS servers, here's what you need to append to your hosts file:
192.168.23.21 www.btopenzone.com
192.168.23.22 my.btopenzone.com
Connection should be pretty seamless with OpenDNS servers permanently residing
in etc/resolv.conf.