The original title is "DNAT Explained: Publishing an Internal Service Through One Public Address and Port"

Short summary

This hands-on Protocol Lab tutorial walks through destination NAT (DNAT/port forwarding) using containerlab and iptables. It explains how DNAT maps a public address:port to an internal service, why it happens in PREROUTING, and how conntrack handles reply un-NATing. The lab includes full topology, configs, and scripts in a public GitHub repo.

• •DNAT maps public IP:port to internal service, complementing SNAT from Lab 20
• •Explains PREROUTING vs POSTROUTING chain placement and conntrack reply handling
• •Full containerlab lab with scripts, RFC references, and step-by-step commands

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