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Difficulty: HardInside Source NAT and PAT Configuration and Verification

A network engineer needs to configure static Port Address Translation (Port Forwarding) on a Cisco IOS router to allow public users on the Internet to access an internal HTTP web server. The internal web server is assigned private IPv4 address 10.1.1.5010.1.1.50 and listens on TCP port 8080. External connections should be directed to the router's public IPv4 address 203.0.113.10203.0.113.10 on TCP port 80808080.

What exact Cisco IOS global configuration command must be entered to establish this static NAT mapping?

Answer: ip nat inside source static tcp 10.1.1.50 80 203.0.113.10 8080

Answer

ip nat inside source static tcp 10.1.1.50 80 203.0.113.10 8080
The correct Cisco IOS command for configuring static Port Address Translation (port forwarding) follows the structure: 'ip nat inside source static <protocol> <local-ip> <local-port> <global-ip> <global-port>'. Therefore, entering 'ip nat inside source static tcp 10.1.1.50 80 203.0.113.10 8080' maps incoming connections on public TCP port 8080 to internal server 10.1.1.50 on port 80.

Step-by-Step Solution

1
Identify the static NAT configuration prefix for inside source address translation.
The initial keywords are 'ip nat inside source static'.
Static translation maps a specific inside local socket to an inside global socket.
2
Specify the Layer 4 transport protocol.
Add the keyword 'tcp'.
Static PAT (port forwarding) requires defining whether TCP or UDP is being translated.
3
Specify the inside local IP address and port number.
Add '10.1.1.50 80'.
This defines the internal server's private socket (IP and service port).
4
Specify the inside global IP address and port number.
Add '203.0.113.10 8080'.
This defines the public IP and port presented to the external network.

Key Concept

Static Port Address Translation (Static PAT / Port Forwarding)
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Topics

Inside Source NAT and PAT Configuration and Verification

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