Networking

Julia Evans introduces a 24-page illustrated zine following a download across the network: packets, DNS, sockets, TCP, HTTP and TLS, plus layers and ports.

Explains when to change Wi-Fi channels, which channels do not overlap (1, 6, 11 in the US for 802.11b/g), and what to do otherwise: keep networks five channels apart, reduce transmit power, or separate access points.

Describes how a router behind an ISP gateway splits the network into two private networks, which can break gaming, VPNs, port forwarding and some SSL sites. It points to a separate article for the fixes.

Advice on band and channel choice: on 2.4 GHz use channel 1, 6 or 11, prefer the least crowded one, and note that Auto channel is not always best; use a Wi-Fi analyzer to check.

Explains that DoH wraps DNS queries in ordinary HTTPS on port 443 so they cannot be easily forged or tampered with and blend in with web traffic. The page links to separate setup guides rather than listing steps.

Explains that double NAT can hurt gaming, port forwarding and UPnP, and recommends removing the ISP router or putting it in bridge mode. Bridge mode on a single Wi-Fi device is a less-preferred fallback that disables some features.

Thread noting the channel is set on the access point, not the clients. Replies suggest scanning with OpenWrt's channel analysis, setting the correct country code, and letting the router choose automatically.

Microsoft advises against disabling IPv6 on Windows and suggests the 'Prefer IPv4 over IPv6' prefix policy (DisabledComponents = 0x20) as a troubleshooting alternative. Editing the registry is risky: back it up first, and note that the correct disable value is 0xFF, not 0xFFFFFFFF.

The Nmap book chapter on finding live hosts in a range: combining ICMP, TCP and UDP probes and skipping port scans with -sn. Useful for listing devices on your own LAN; only scan networks you own or manage.

A thread on PPPoE and MTU. The answer: keep the WAN and LAN MTU at 1500 because lowering it only shrinks the PPPoE payload further, and rely on the default MSS clamping on the WAN zone to handle the overhead.

A way to keep two routers without double NAT: reserve the OpenWrt router's address on the upstream router, add a route to OpenWrt's LAN via that address, and untick masquerading on OpenWrt's WAN zone.