Você pode criar VPN usando o ssh. Aqui está a seção relevante de man ssh
:
SSH-BASED VIRTUAL PRIVATE NETWORKS
ssh contains support for Virtual Private Network (VPN) tunnelling using the tun(4)
network pseudo-device, allowing two networks to be joined securely. The sshd_config(5)
configuration option PermitTunnel controls whether the server supports this,
and at what level (layer 2 or 3 traffic).
The following example would connect client network 10.0.50.0/24 with remote network
10.0.99.0/24 using a point-to-point connection from 10.1.1.1 to 10.1.1.2,
provided that the SSH server running on the gateway to the remote network,
at 192.168.1.15, allows it.
On the client:
# ssh -f -w 0:1 192.168.1.15 true
# ifconfig tun0 10.1.1.1 10.1.1.2 netmask 255.255.255.252
# route add 10.0.99.0/24 10.1.1.2
On the server:
# ifconfig tun1 10.1.1.2 10.1.1.1 netmask 255.255.255.252
# route add 10.0.50.0/24 10.1.1.1
No final, você terá uma interface de túnel que poderá usar para encaminhar seu tráfego.