# cat usbdnet
#!/bin/bash
  
  num=`ifconfig | grep usb0 | wc -l`
  
  if [ $num -eq 0 ] ; then
        # ifconfig usb0 192.168.1.220 netmask 255.255.255.255 up
        ifconfig usb0 192.168.1.220 netmask 255.255.255.0 up
        route delete -net 192.168.1.0/24 usb0
        route add -host 192.168.1.221 usb0

        # Set up our tables.
        iptables -t nat -F
        iptables -t nat -A POSTROUTING -j SNAT -o eth0 --to 192.168.1.212
        echo 1 > /proc/sys/net/ipv4/ip_forward
  fi