Cellular Network Infrastructure » Core Network (CN) » OsmoGGSN (former OpenGGSN)

From the user manual:

It’s possible to run OsmoGGSN without root privileges if the tun devices are already configured.
The interface creation + configuration must then happen before osmo-ggsn starting up.
[...]
With the tun device pre-configured in one of the ways outlined above, the main changes in your osmo-ggsn.cfg file are:
• remove ip ifconfig directive,
• make sure that no shutdown is present in the apn section as well as no shutdown ggsn in the ggsn section.

With this configuration, a tun device created by /etc/network/interfaces will be removed when osmo-ggsn shuts down and ifup -f apn0 must be used to recreate it, before starting osmo-ggsn again.