OpenVPN fails to replace the default route on some UMTS/PPP connections. This script fixes the default route by adding the gateway information to the default route.

normalize-default-route.sh

#!/bin/bash

if [ $(ip route list exact default |\
    awk '/^default/ {print $2}') = dev ];
then
  IF=$(ip route | awk '/^default/ {print $3}')
  GW=$(ip address show $IF |\
  awk '/peer/ {print $4}' | cut -d"/" -f1)
  ip route replace default via $GW dev $IF
fi