tunctl behaviour for Linux.

For IPv4 addresses, beam needs to have privileges to configure interfaces.

To add cap_net_admin capabilities:

   sudo setcap cap_net_admin=ep /path/to/bin/beam.smp

To check the privileges:

   getcap /path/to/bin/beam.smp

To remove the privileges:

   sudo setcap -r cap_net_admin=ep /path/to/bin/beam.smp