Quoting Eric Paris (eparis(a)redhat.com):
So the kernel socket(s) would be per network namespace, but we
divide
messages per user namespace? Which socket do I send them on,
considering the possible crazy many<->many mappings between user and
network namespaces. It all makes me cry a little.
not many-many - each netns is owned by exactly one userns. The userns
from which the netns was created.
-serge