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Spurious TCP Requests sent by Leetcode

The leetcode website attempts a TCP connection to the non-existant domain sockets.leetcode.com every few seconds. I found out because I was accessing leetcode through a proxy, and the logs are filled with error messages. There are no DNS records of any kind at this domain, so connection always results in a failure.

I am unable to find out who initiated the request. It does not show up in the Network tab of DevTools, and I can’t find it in the status page for webrtc. I even blocked all webrtc traffic, and it still shows up. It’s the same whether I use Windows or Linux, Firefox, Edge or Chrome.

This is a really annoying bug. Hope leetcode hires me for their internship, so I can fix it.