Quick Linux Connection Forward Howto

How to do connection shareing quickly. Starting a dhcp server may also be a good idea.

   # Set up IP FORWARDing and Masquerading
   iptables --table nat --append POSTROUTING --out-interface ppp0 -j MASQUERADE
   iptables --append FORWARD --in-interface eth0 -j ACCEPT

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