nat

sharewall is very good

#
# Shorewall version 4 - Nat File
#
# For information about entries in this file, type "man shorewall-nat"
#
# For additional information, see http://shorewall.net/NAT.htm
#
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#EXTERNAL	INTERFACE	INTERNAL	ALL		LOCAL
#						INTERFACES
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE