Multi-segment Linux Router using Netplan and Nftables: DMZ, SNAT/DNAT, MGMT

This article provides a comprehensive guide on building a multi-segment Linux router based on Ubuntu 24.04, Netplan, and nftables. The author demonstrates the process of configuring network infrastructure using a lab setup that includes LAN, DMZ, and MGMT segments. The material covers key aspects of network administration: from basic addressing and IP forwarding to implementing stateful filtering via conntrack, configuring SNAT/DNAT, and deploying a local DNS. Special attention is given to isolating critical network segments and diagnostic methods. The article is accompanied by configuration examples and commands, making it a useful practical guide for system administrators and DevOps engineers looking to deepen their knowledge of Linux networking. The entire lab setup is available in the author's GitHub repository, allowing readers to replicate the described architecture both locally and in cloud environments.