Like VPN using ssh. Script that creates an ssh tunel associated to a "tun" interface to use it as default interface.

SshVpn.sh

#!/bin/bash
# Like VPN using ssh. Script that creates an ssh tunel associated to a "tun" interface to use it as default interface. See man ssh option -w for more info.
# 1. Establish ssh tunel
# 2. Creates and associate it to the tun interface
# 3. Redirect al system trafic to this interface
#
# Like tipical VPN connections, all your traffic is tunneled by this p2p connection
# IMPORTANT: 
# 	On the client in /etc/ssh/ssh_config set Tunnel point-to-point
# 	On the sercer in /etc/ssh/sshd_config set PermitTunnel point-to-point

VPN_GATEWAY=192.168.42.1
ORIGINAL_GATEWAY=`ip route show | grep ^default | cut -d ' ' -f 2-5`
DOMAIN="dyn.dns.domain"

INTERFACE=tun5
REMOTEADDRESS=$( dig +short  $DOMAIN)

MYIP=192.168.42.2

echo "Server ip found: " $REMOTEADDRES

sudo ssh -o PermitLocalCommand=yes -o LocalCommand=\
"sudo ifconfig $INTERFACE $MYIP pointopoint $VPN_GATEWAY netmask 255.255.255.0;"\
"sudo ip route add $REMOTEADDRESS $ORIGINAL_GATEWAY;"\
"sudo ip route add $VPN_GATEWAY dev $INTERFACE;"\
"sudo ip route add 0.0.0.0/1 via $VPN_GATEWAY dev $INTERFACE;"\
"ip route add 128.0.0.0/1 via $VPN_GATEWAY dev $INTERFACE" -o ServerAliveInterval=60 -w 5:5 root@$REMOTEADDRESS "sudo ifconfig $INTERFACE $VPN_GATEWAY pointopoint $MYIP netmask 255.255.255.0; echo tun5 ready"