Use openconnect to connect to VPN while allowing internet access (works for wireless interface only)

vpn.sh

#/bin/bash

##########################################################################
# Uses openconnect to connect to a VPN gateway and ssh into the specified
# remote host as per the arguments passed to the script, and route internet
# traffic through a default gateway.
# Note: The script assumes internet connectivity on the wireless interface
# "usage: ./vpn <remote_user> <remote_host>"
###########################################################################

VPN_GATEWAY=${VPN_GATEWAY:-127.0.0.1}        # Make sure to set this correctly to your VPN Gateway IP Address
VPN_USERNAME=${VPN_USERNAME:-me}             # Your VPN username
GROUP=${GROUP:-None}                         # Set this if VPN profile falls under an Auth Group
TUNNEL_INTERFACE=tun0
WIRELESS_INTERFACE=$(ls /sys/class/net/ |grep w)
NETWORKS=("")                                # Space separated list of networks to add VPN routes for
DEFAULT_GATEWAY=$(ip route show default | awk '/default/ {print $3}')
USER=$1                                      # Remote server's ssh user
REMOTE_HOST=$2                               # Remote ssh server's host name / i.p address

function usage
{
    echo "usage: ./vpn <remote_user> <remote_host>"
}

function parse_args() {
    args=$#
    if [ $args -ne 2 ]
    then 
        usage
        exit
    fi
}

function reconfigure_routes() {
    # Delete any default routes created on tunnel interface
    sudo route del -net 0.0.0.0 netmask 0.0.0.0 dev $TUNNEL_INTERFACE

    # Add default route for non-vpn traffic
    sudo ip route add default via $DEFAULT_GATEWAY dev $WIRELESS_INTERFACE proto static

    # Add static routes for data center networks via tunnel interface
    for network in ${NETWORKS[@]}
    do
        sudo route add -net $network dev $TUNNEL_INTERFACE
    done
}

function connect_to_vpn() {
    echo "Running openconnect"
    sudo openconnect -b --no-cert-check -u $VPN_USERNAME -s /etc/vpnc/vpnc-script --authgroup $GROUP $VPN_GATEWAY
    failed=`echo $?`
    if [ -n $failed ]
    then
        reconfigure_routes
    fi
}

parse_args $(echo $*)

if [ -z "$DEFAULT_GATEWAY" ]
then
    echo "ERROR: No Default Gateway set! Connect to the internet and try again."
    exit
fi

connected=`ps aux | grep openconnect | grep -v grep | wc -l`

if [ $connected -eq 0 ]
then
    echo -e "Not connected to VPN. Connecting...\n"
    connect_to_vpn $user $remote_host
fi

# SSH to the remote host
ssh $USER@$REMOTE_HOST