Transparent Proxy seems to break Mail.app on Big Sur

App & System Services Networking Network Extension

Created Sep ’20

Replies 17

Boosts 0

Views 2.5k

Participants 4

I'm having a problem developing a "Transparent Proxy"-type network extension. The problem started with Big Sur. Everything seems to work on Catalina.

Steps to reproduce:

Disable (set link-local only) IPv6 on your network interface.
Start a simple TransparentProxy network extension that forwards IPv4 TCP traffic (I've attached an example to feedback FB8690357).
Open Mail.app and try to add a Yahoo account.
Login either fails immediately with "Network connection timed out" or shows an error screen.

P.S. QQMusic (an app from AppStore) also doesn't work on BigSur when network extension is active. It receives responses from the server proxied by the extension, but fails to display them for some reason.

Browsing with Chrome and other network usage seems to work as normal.

Boost

ngorskikh OP

Oct ’20

Hi, @meaton! It seems, on the new macOS 10.0.1 beta, with NETransparentProxyProvider, issues reported in this thread, including the proxy issue, are resolved. Thanks for the support!

Systems Engineer OP

Apple

Oct ’20

It seems, on the new macOS 10.0.1 beta, with NETransparentProxyProvider, issues reported in this thread, including the proxy issue, are resolved. Thanks for the support!

No problem! Glad to hear things are working for you.

Matt Eaton
DTS Engineering, CoreOS
meaton3@apple.com