GoKawiil
Tech News
This is a developer-focused list of common wrong assumptions about local area networks, covering NAT, MAC addresses, DHCP, protocols and reachability. It matters because software that assumes a simple, well-behaved LAN often breaks in real deployments with double NAT, spoofed or duplicate MAC addresses, multiple DHCP servers, or mixed Wi-Fi/Ethernet environments. For anyone building device discovery, licensing, or peer-to-peer features, it's a practical checklist of edge cases to design around.
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Each entry is phrased as the falsehood. Some of these may sometimes be true and sometimes be false.
NAT
My LAN is behind a NAT.
I’m only behind one NAT.
My LAN isn’t behind a NAT.
My IPv6 hosts aren’t behind a NAT.
If I have a RFC 1918 address, I’m behind a NAT.
If I don’t have a RFC 1918 address, I’m not behind a NAT.
NAT only translates addresses.
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