Install bluez-utils, make sure you have the required kernel modules and plug in your USB dongle.
Start bluez-utils (and/or set to auto-start).

Create a file /etc/ppp/peers/dun with the following content:
  460800
  debug
  192.168.1.1:192.168.1.2
  ms-dns YOUR_DNS_ADDRESS
  lock
  crtscts
  noauth

Substitute the IP address of your DNS server for YOUR_DNS_ADDRESS. You can find it out by looking into the file /etc/resolv.conf (look for 'server aaa.bbb.ccc.ddd' and write ms-dns aaa.bbb.ccc.ddd into the above file.)
Set up internet connection sharing with the following two commands (as root):

iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -j MASQUERADE

echo 1 > /proc/sys/net/ipv4/ip_forward


Give the following command as root

dund --listen call dun

You will need to modify your configurations or startup scripts to automatically start dund after reboot. In my case (Debian sarge) I had to edit /etc/default/bluez-utils, and change the respective lines to the following:

DUND_ENABLED=1
DUND_OPTIONS="--listen call dun"

Also you need to add the two internet connection sharing setup command to some startup script (look for rc.local somewhere).

Von: http://gnubox.dnsalias.org/gnubox/