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It's actually several things, including user agent strings, HTTP accept/accept language. The underlying script allows you to route between n different destinat
by ipsin 15y ago
It's actually several things, including user agent strings, HTTP accept/accept language.
The underlying script allows you to route between n different destinations based on header matching and netmasks. The shortened URL is just a hash of the rule set, with a sequence number appended in case of collisions.
- phillco 15y agoClever. I assume the only way for Facebook and Twitter to circumvent this would be to fake all of the HTTP headers sent by, say, a modern version of Firefox. I don't think it's cheating - even though the tools are bots, their job is to preview the content their users are about to see. Even then, the author could probably find out which IP addresses are used by Twitter and Facebook's lookup engines and send them the innocuous version. However, I just did a test on my own server, and Facebook used two different IPs (69.171.228.246 and 69.171.224.245) for the same request. Pretty big range.