MiFi device that offers site-to-site VPN

[garnet]

+1 for
RPi+3g/4g usb stick
configure the pi's wifi module to accept ad-hoc connections and share the VPN connection.
Along these lines.

[SimonMac]

+1 for
RPi+3g/4g usb stick
configure the pi's wifi module to accept ad-hoc connections and share the VPN connection.
Along these lines.

Can the RPI be powered from just USB?

[stek]

I wonder if Cisco's router on a stick will work, the ASAv?

https://blog.sanghera.me.uk/cisco-asav-vlans/

Cisco ASA not for the faint-hearted though and I'm not sure the above link is what you want, might get some ideas from it though....

[garnet]

Can the RPI be powered from just USB?

I think so, but I am not sure a USB port can supply ~2A, because you might need this if you have 3G USB dongle + wifi on.

[Contreras]

Can the RPI be powered from just USB?

Yes it can. Apparently it can suffer brown-out problems if powered from a weak supply and the Pi itself powering USB devices. The 'official' wall cube for the Pi 3 is now rated 2.5A. The Pi 3 also has on-board wifi. I'm right now putting one in a nice little case (99p from China inc p&p! how do they do that?) which would suit a homebrew portable setup if you can make it work.

Do you know if it's possible to get on the VPN from a Linux PC?

[WTFH]

You used to be able to buy dual USB cables for the scenario of needing more power. If one port (such as the charging one) doesn't give enough juice, then connect to a second one as well.