Explore and enter Linux network namespaces

You can see ALL network namespaces and process pids associated with each. It is different from "ip netns list" by ability to see unnamed namespaces, i.e. those which are not bind mount to /var/run/netns directory. See 'man namespaces' for more details.

Example usage

Make sure that you have read access to all /proc/<pid>/ directories. Otherwise information will not be full.

go build nsexplore.go
# or download binary from github:
wget https://github.com/mihgen/nsexplore/releases/download/v0.3/nsexplore
chmod +x nsexplore

# List all network namespaces, and pids associated.
./nsexplore -a

Example output:

 NS NUMBER               FILE  PID
4026531957  /proc/8053/ns/net  8053,8077,10776,11790
4026532152    /run/netns/myns

To see what those pids are:

ps -fp 8053,8077,10776,11790

Enter network namespace by number and run "ip addr":

./nsexplore -j 4026532152 ip addr

Docker containers

If a process is running withing a Docker container, it takes a couple of steps to get a name of this container.

1. Get process pid

./nsexplore
 NS NUMBER                FILE    PID  CMD
4026532647  /proc/13240/ns/net  13240  pause

2. Get PPID of process you are interested in

ps -fp 13240,13486
UID        PID  PPID  C STIME TTY          TIME CMD
root     13240 13223  0 Nov19 ?        00:00:00 /pause
nobody   13486 13470  0 Nov19 ?        00:03:38 dnsmasq -k -7 /etc/dnsmasq.d

Note PPID of dnsmasq is 13470.

3. Check PID name of that process

ps -fp 13470
UID        PID  PPID  C STIME TTY          TIME CMD
root     13470  6135  0 Nov19 ?        00:00:00 docker-containerd-shim 5edae692e6cc032f884...

Note sha of container in the output.

4. Get container name from docker ps output

docker ps | grep 5edae692e6