Script to connect to openvpn server

connect_vpn.sh

#!/bin/bash

# Change file names here
PRIMARY=primary.ovpn
BACKUP=backup.ovpn

# Trap signal handler
trap_end() {
    sudo rm .tmp-pass
    exit
}

# Ping server give as arguemtn to check for internet connectivity
check_connection() {
    # $1 --> Server to ping
    echo $host
    if !(ping -q -c 1 -W 1 $1 >/dev/null); then
        # If ICMP is blocked, try alternate ways
        if !(nc -zw1 $1 443); then
            return 1
        fi
    fi
    return 0
}

# Check internet connection by pinging Google DNS server
check_internet_connection() {
    if !(check_connection 8.8.8.8); then
        echo "Internet connection is down"
        trap_end
    fi
    echo
}

# Check iiit connection by pinging intranet and mess
# mess --> 10.4.20.179
# intranet --> 10.4.21.84
# Replaced with ip's incase dns fails/takes too much time
check_iiit_connection() {
    if !(check_connection 10.4.21.84); then
        if !(check_connection 10.4.20.179); then
            return 1
        fi
    fi
    return 0
}

# Check connection at start
check_internet_connection

# Ask for super user access to script from start
# so as to not prompt if primary server fails
# and temporary server needs to be restarted
if [[ $(whoami) != "root" ]]; then
    echo "Try again with sudo access"
    exit
fi

# Kill script on signal by user
trap trap_end SIGINT
trap trap_end SIGTERM


# Read username and password
read -p "Username: " username
read -s -p "Password: " password

# Newline after entering password
echo

# Store username and pass to a file so as to be not prompted
# incase primary server fails
echo $username > .tmp-pass
echo $password >> .tmp-pass
chmod 400 .tmp-pass

# If the user presses ^C, the script exits by the trap handler
# If the user didnt press ^C and a command fails, the command next
# in line will be executed

# Launch Primary Server
echo "Connecting to Primary Server"
openvpn --config $PRIMARY --auth-user-pass .tmp-pass > /dev/null &
primary_pid=$!

# Poll every 20 sec to check if can still connect to iiit network
while true; do
    sleep 20
    # Check if still connected to internet
    check_connection

    # Check if connected to iiit network
    if !(check_iiit_connection); then
        echo "Cannot connect to Primary link"
        kill -9 $primary_pid
        break
    fi
done

# Primary Server failed. Use Temporary Server
echo "Connecting to Backup Server"
openvpn --config $BACKUP --auth-user-pass .tmp-pass > /dev/null &
backup_pid=$!

# Same as previous check
while true; do
    sleep 20
    # Check if still connected to internet
    check_connection

    # Check if connected to iiit network
    if !(check_iiit_connection); then
        echo "Cannot connect to Temporary Link"
        kill -9 $backup_pid
        break
    fi
done

# Inform of failure
echo "Both Servers failed"

quit