Subject: [v6ops] AT&T wireless transparent web proxy breaks Happy Eyeballs...

From: Steve Wallace <[email-masked]>
Date: Tue, 1 Jun 2021 19:58:31 +0000

Greetings,

While troubleshooting a problem accessing a server via my iPhone hotspot, I observed that AT&T’s web proxy breaks Happy Eyeballs. The server I was attempting to access has both A and AAAA DNS records, however it was only bound to IPv4. AT&T’s web proxy allowed my browser to fully establish an IPv6 TCP session towards the server, before the proxy attempted to establish a session with the actual server.

Happy to share additional details if that’s useful.

Based on the following paper, which is a bit dated (at the time the proxies weren’t proxying IPv6 sessions), I suspect something similar happens over other wireless networks:

https://www.researchgate.net/publication/272295228_Investigating_Transparent_Web_Proxies_in_Cellular_Networks

Steven Wallace
Internet2