Static PAT: Port Forwarding to an Inside Server

Bundle lab

Configure static PAT (port forwarding) on a Cisco IOS edge router so an outside client can reach an inside HTTP service on TCP/8080 using a dedicated public IP that is not the router's interface. Validate using curl from the outside host and NAT show commands on the router.

Learning objectives

• Mark inside and outside interfaces correctly so translations occur only across the router edge
• Implement static PAT to forward TCP/8080 from a dedicated public IP to an inside server IP/port
• Retain working routing before translation with a default route toward the ISP
• Verify static port-forwarding from the outside using curl and confirm translations with IOS show commands
• Differentiate between static PAT for inbound access and PAT/overload used for outbound flows

Troubleshooting focus

• Outside host cannot connect to 203.0.113.3:8080 because ip nat inside/outside roles are reversed on the router
• Static PAT uses the router’s interface IP instead of the dedicated public IP, breaking the test plan
• Public NAT address is not on the connected outside segment, so return traffic never arrives
• Inside server is not listening on 8080 or the process crashed; port-forwarding appears correct but connection resets
• Default route missing on the NAT router; SYNs arrive but the server’s replies cannot reach the outside network
• Port number mismatch (mapped 8080 but testing 80) resulting in timeouts