There’s a quick way to test the offline behaviour of programs on Linux.

shell

unshare -c -n bash

Then only loopback is available.

  
    shell
  
  $ ip addr
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

List network namespaces with lsns.

  
    shell
  
  $ lsns -t net
NS  TYPE NPROCS PID   USER  NETNSID    COMMAND
999 net  2      111   user  3          systemd
888 net  1      222   user  unassigned └─bash

#gists #linux