High CPU usage when IPv6 is blocked at firewall

[afan-ai]

Hi team,

I've blocked IPv6 at my firewall, and my headless connector (using a service account) on my Linux server (Alma 9) uses 100% CPU on a single core (non-stop!)

The fix was to disable IPv6 at a kernel level:

sysctl -w net.ipv6.conf.all.disable_ipv6=1
sysctl -w net.ipv6.conf.default.disable_ipv6=1

Using "strace", I observed the client in a busy polling loop. This consumes 100% of one CPU core:

25ms timeout, no events:
epoll_wait(7, [], 32, 25) = 0

Check time:
gettimeofday(...)

Repeat ~40 times/second
epoll_wait(7, [], 32, 25) = 0

Steps to reproduce the issue:by:

1. Deploy the Twingate client on a Linux host with IPv6 enabled (ideally Alma, since this is NOT an issue on my other Rocky Linux system)!
2. Blocking IPv6 at the perimeter (firewall)
3. Attempting to connect to a remote network

The client will spin at 100% CPU until IPv6 is disabled on the host.

[linear]

OSS-101