The third number in each of the addresses below should be 1, not 10. Sorry about the typos. > ipchains -A forward -s 192.168.10.0/24 -d ! 192.168.10.0/24 -j MASQ > > Configure the machines A, B and C with their gateway set to 192.168.10.1 and > setup their DNS, and your should be set.