Originally Posted by Poucket
Will machine B also have internet through the alias?
in that situation, no. it can be make throught /etc/rc.d/rc.ip_forward make an executable, and make an /etc/rc.d/rc.firewall script like as
echo "Starting Firewall & NAT "
#Flush all chains
$IPTABLES -t nat -F
# Erase all chains
$IPTABLES -t nat -X
#$IPTABLES -P INPUT DROP
#$IPTABLES -P OUTPUT DROP
#$IPTABLES -P FORWARD DROP
$IPTABLES -P INPUT ACCEPT
$IPTABLES -P OUTPUT ACCEPT
$IPTABLES -P FORWARD ACCEPT
### cannot use -i with postrouting!
$IPTABLES -t nat -A POSTROUTING -s 192.168.0.0/24 -o eth0 -j MASQUERADE
but that - firewalling, address translation and so - is another, big, topic...
and with situation as there, when outer ( internet) in inner network is one, it not be safe thing, imho. inner, private network must be physically separated from outer, and that require additional network card in A machine.