namespaces
4 commands
4 shown
Namespaces of a specific PID
List all ns a PID belongs to; compare ns inode links to prove shared namespace
lsns -p <pid>; readlink /proc/<pid>/ns/net /proc/1/ns/net # equal inode = same netns
Tcpdump inside a container netns from host
Sniff a container's traffic using host's tcpdump via its netns; no tools needed in image
PID=$(docker inspect -f '{{.State.Pid}}' <name>); nsenter -t $PID -n tcpdump -ni any -c 50
Inspect sockets in a process netns/mntns
Enter newest proc's net+mount+pid ns and list listening sockets it actually sees
nsenter -t $(pgrep -n <proc>) -n -m -p ss -tlnp
Isolated sandbox with unshare
Spawn shell in fresh net+pid ns with private /proc; ip netns for named netns testing
unshare --net --pid --fork --mount-proc bash # then: ip netns add test; ip netns exec test ip a
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