[SOLVED] Error when creating a network namespace inside a docker container. error: mount --make-shared /run/netns failed: Permission denied

Issue

I'm getting an error when creating a network namespace inside a docker container saying permission denied.

command  
ip netns add red

error
mount --make-shared /run/netns failed: Permission denied

I am running an image ubuntu:20.10 and tried by adding specific capabilities to the container and it did not help.

docker run -it --rm --name=ubuntu --cap-add CAP_SYS_ADMIN --cap-add NET_ADMIN ubuntu:20.10
apt-get update && apt-get install -y net-tools && apt-get install -y iproute2

Even after adding all capabilities issue remain same.

docker run -it --rm --name=ubuntu --cap-add ALL ubuntu:20.10

Solution

--cap-add & --privileged are not same.
Ref: https://docs.docker.com/engine/reference/run/#runtime-privilege-and-linux-capabilities

Issue is sorted by running the container with privilege. Capabilities seems not required for adding network namespace.

docker run -d --name=<name> --network=none --privileged <image>:<tag>

Answered By - Isuru Amarathunga

Answer Checked By - Gilberto Lyons (WPSolving Admin)