Fix for Docker v26.0.1 and above

[Jip-Hop]

Users who are still using host networking will run into issues when they upgrade docker to v26.0.1 and above. I recommend anyone using docker inside their jail to stop using the docker_compatible config option a.s.a.p. and start using macvlan or bridge networking. Refer to the readme for the new recommended setup to run docker in a jail. The new setup is more secure and because the jail has its own networking namespace it's less likely to run into compatibility problems (which is what's causing the docker issues). For a smooth migration I recommend to follow these migration instructions. My docker jail is using bridge networking and the latest docker v26.1.0 is running perfectly!

[neoKushan]

Looking into this issue, it seems v26.1.1 potentially fixes the underlying change?

https://github.com/moby/moby/releases/tag/v26.1.1

Resolve an issue preventing container creation on hosts with a read-only /proc/sys/net filesystem. If IPv6 cannot be disabled on an interface due to this, either disable IPv6 by default on the host or ensure /proc/sys/net is read-write. Otherwise, start dockerd with DOCKER_ALLOW_IPV6_ON_IPV4_INTERFACE=1 to bypass the error.

Am I correct that this is the underlying cause, or am I way off?

[Jip-Hop]

I think so, but I still recommend bridge or macvlan networking over host networking to prevent these issues in the future.