I assume Internet is connected on eth0 and your internet network on eth1
Install dhcp3-server. Make it listen on eth1. Edit /etc/dhcp3/dhcpd.conf:
# The ddns-updates-style parameter controls whether or not the server will
# attempt to do a DNS update when a lease is confirmed. We default to the
# behavior of the version 2 packages ('none', since DHCP v2 didn't
# have support for DDNS.)
ddns-update-style none;
Filling in the DNS manually seems the only way it works. Ripped out /etc/resolv.conf of the gateway.
# option definitions common to all supported networks...
option domain-name "pp.htv.fi";
option domain-name-servers 213.243.153.171, 213.243.153.172;
default-lease-time 600;
max-lease-time 7200;
# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
authoritative;
# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
log-facility local7;
subnet 192.168.0.0 netmask 255.255.255.0 {
option routers 192.168.0.1;
range 192.168.0.10 192.168.0.20;
}
And finally iptables:
iptables -t nat -F
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.0.0/24 -j MASQUERADE