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How to configure NAT for Internet acces on cisco router
NAT (Netword Address Translation is a technolegi use to rewrite the source ip in the ethernet header, its a must when connecting to the internet, because the internet dosent know the RFC1918 addresses you are using inside of your network and therefore cannot respond if the packets source isn’t a public ip that the internet knows of.
Nat can be usefull in other scenarious asswell, some legacy application might require being contacted by one ip only or similar cases.
Step 1: Login to global configuration mode
# Type enable to enter KANIKKEHUSKE
enable
# Type Configure Terminal to enter global configuration mode
configure terminalStep 2: Configure inside interface
Do this for all interfaces that needs to be NAT’ed.
interface <internal interface>
ip nat insideStep 3: Configure the outside interface
interface <outside interface>
ip nat outsideStep 4: Configure NAT rules
# Configure NAT rule
ip nat inside source list 1 interface <WAN interface> overload
# Configure acces list for nat rule
acces-list 1 permit <network> <Wildcard mask>
# Configure for each network like this:
access-list permit 1 10.1.0.0 0.0.0.255
access-list permit 1 10.2.0.0 0.0.0.255