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Following have been tested on [[Cisco CSR V1000 virtual router]] to allow users to access Internet via PAT (Overload NAT) via Cisco router

# Create a new virtual Cisco router or connect to a physical router over terminal / console
# Ensure IP addresses are given to two interfaces - Outside (Eg gigabitethernet 1 in this article) and Inside (GigabitEthernet 2 in this article)
# Create an access list for clients / users who can use PAT facility.   For example
#:<pre>
#:: access-list 1 permit 10.1.3.0 0.0.0.255
#:</pre>
#: Here 10.1.3.0/24 is the IP addresses of the local clients who want to use PAT service via router
# '''(Optional)''' if there is more than one public IPs that can be used for PAT then we can define a IP pool for PAT purposes using.  
#:<pre>
#:: ip nat pool <pool-name> <pool-start-ip> <pool-end-ip> netmask <net-mask> 
#:</pre>
#:: If this is not the case we can simply do PAT via router gigabitethernet 1 (outside) interface IP
# Configure nat using interface IP of outgoing (public) interface (Eg gigabitEthernet 1 in below example)
#:<pre>
#:: ip nat inside source list 1 interface GigabitEthernet 1 overload
#:</pre>
#: where: 1 is the access list defined for local users
#: Gigabitethernet 1 is the outside (public) interface for outgoing traffic
#: '''overload''' is critical to configure pat / overload nat
# '''(Optional)''' Other option is to configure PAT with pool of addresses using
#::<pre>
#::: ip nat inside source list 1 pool <pool-name> overload
#::</pre>
# Specify inside and outside interfaces.  For example if Gigabitethernet is outside (public) interface and Gigabit interface2 is inside (LAN / private) interface use:
#:<pre>
#:: config t
#::   interface GigabiEthernet 1
#::      ip nat outside
#::   interface GigabitEthernet 2
#::      ip nat inside
#:</pre>
# Configure a system in inside IP range allowed as per access list 1 in above example and give gateway of this machine as router IP (Gigabit ethernet2 LAN / private IP).  Try to reach a machine which is reachable only via outside IPs (Eg Internet)
# On router look at nat transalations using:
#:<pre>
#:: show ip nat translations
#:</pre>
# If everything is working as expected save configuration:
#:<pre>
#:: copy running-config startup-config
#:</pre>


Refer:
* https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nat/configuration/15-mt/nat-15-mt-book/iadnat-addr-consv.html#GUID-B8A2254C-2E6B-4035-819C-F87144FCAD1B__GUID-F8E76431-B0B0-4D98-8881-37B7B124DDFD





[[Main Page|Home]] > [[Switch configuration notes]] > [[Configure Cisco router outgoing PAT or overload NAT for users to access Internet]]