28 Apr 2007

how bbc's region locking works


i was blocked out of some video streams from bbc's website today, and i realised what was happening.

it turns out bbc's website enforces the "uk only" access restriction by making it's dns servers return a different IP depending on where you are. normally this isn't a problem, but i've just started using opendns as my dns servers and thus they are resolving www.bbc.co.uk differently than machines that were not using opendns.

here is the dns entry from my macbook pro with opendns:
mcbookpro:~ liquidx$ host www.bbc.co.uk
www.bbc.co.uk is an alias for www.bbc.net.uk.
www.bbc.net.uk has address 212.58.240.33
here is the same dns entry from my macbook pro without opendns:
mcbookpro:~ liquidx$ host www.bbc.co.uk
www.bbc.co.uk is an alias for www.bbc.net.uk.
www.bbc.net.uk has address 212.58.224.116
the dns name doesn't just resolve to one ip, but a number of ips by round robin. from just preliminary observation, anything 212.58.240.* is for overseas, and 212.58.22{4,5,6,7}.* is for uk only.

although it is not definitive, but wouldn't that technically mean if you use a dns server inside the UK you would probably be able to get around that uk only restriction?

[update: turns out that apart from that, they block non-UK access via the rtsp stream as well, so just fakking the DNS won't work. however, at least that is one part of the ACL puzzle. it's a bit weird that they would do that DNS weirdness. i must investigate that further.]


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