Network     CLONE_NEWNET      Network devices, stacks, ports, etc.
We can see the user id is same as the parent shell as expected.
You may read more detailed implementation in this LKML article.
Below copied snipp is from the same article.
Normally, one of the first steps after creating a new user namespace is to define the mappings used for the user and group IDs of the processes that will be created in that namespace.
Together, the ID-inside-ns and length values define a range of IDs inside the namespace that are to be mapped to an ID range of the same length outside the namespace.
The ID-outside-ns value specifies the starting point of the outside range.
UidMappings SysProcIDMap // User ID mappings for user namespaces.
GidMappings SysProcIDMap // Group ID mappings for user namespaces.
ContainerID int // Container ID.
HostID int // Host ID.
Previous story Why Should I learn Go ?
openlinuxlabs on Why Should I learn Go ?
Anuj Agarwal on Why Should I learn Go ?