Today I spent several hours trying to figure out what was going wrong with a web service I’ve been building. The service uses websockets to let browsers and the server send messages to each other over a connection that is held open.

I built and tested the service locally and it worked fine. But when I deployed it to a remote server, the websocket connections were mysteriously dropped 30-35 seconds after they were established. The error messages on the server were cryptic, as were those in the browser. Google came to the rescue, and led me to the eye-opening explanation…

It turns out TalkTalk, my ISP, are also fetching the URLs my browser fetches, after a delay of 30-35 seconds! I guess they’re not doing it with all URLs, probably because they figure the sites are “safe” and not full of content that might be deemed objectionable. All the accesses come from a single IP address (62.24.252.133), and if you block that address or otherwise deny its connection attempts, the websocket problem goes away immediately.

Dear TalkTalk – this is a very bad idea. Here are 3 strong reasons why:

First of all, you’re breaking the web for your own customers, as seen above. When your customers try to use a new start-up service based on websockets, their experience will be severely degraded, perhaps to the point where the service is unusable. Time and money will be spent trying to figure out what’s going on, and people will not be happy to learn that their ISP is to blame. Second, there’s a real privacy issue here. I don’t really want to go into it, but I don’t trust my ISP (any ISP) to securely look after data associated with my account, let alone all the web content I look at. I have Google web history disabled. I don’t want my ISP building up a profile of what the people in this house look at online. There’s a big difference between recording the URLs I go to and actually retrieving their content. Third, it’s downright dangerous. What if I were controlling a medical device via a web interface and TalkTalk were interfering by killing my connections or by replaying my requests? What if there was a security system or some other sensitive controller on the other end? There’s no way on earth TalkTalk should be making requests with unknown effects to an unknown service that they have not been authorized to use. The TalkTalk legal team should consider this an emergency. Something is going to break, perhaps with fatal consequences, and they are going to get sued.

If you want to read more opinions on this issue, try Googling TalkTalk 62.24.252.133. Lots of people have run into this problem and are upset for various reasons.

See also: Phorm.