$ ps auxww | grep $(ip netns pids ns1)
 root  7811  0.0  0.0  46900  1024 ?   Ss   01:05   0:00   /usr/sbin/sshd -o PidFile=/run/sshd-ns1.pid -o ListenAddress=1.1.1.1

 $ ip netns pids ns1 | xargs kill
 $ ip netns del ns1
 $ ip netns identify 1445
 ns1
 $ ip netns monitor
 add ns1
 add ns2
 delete ns2
 delete ns1