networking

A memory-modded 360T7 had run for years until I flashed OpenWrt's bl2 and fip. It then stopped at dram size: 0MB. Every rescue package I found failed for the same reason: OpenWrt's official bl2 drives DDR3 at 2133MT/s, while this router has a DDR3-1600 chip. DRAM initialization failed before the rest of the boot chain could load. I traced the settings in the ATF source, built a bl2 at 1866MT/s, and recovered the router over UART.

The 360V6 has A/B dual-partition flash: two complete rootfs copies and a bootloader slot flag that selects one at boot. Updates write the inactive partition and leave the running one alone. If a write fails or is interrupted, the router can still boot the old system.

OpenWrt's sysupgrade ignored the layout and wrote the running partition in place. A power loss or bad image mid-write left the device unbootable, recoverable only over TTL. I added proper A/B support upstream, and it has merged.

BitTorrent and private-tracker clients benefit from accepting inbound connections, but CGNAT prevents that. Your ISP places multiple subscribers behind one public IPv4 address, so there is no inbound mapping for the home server. Port forwarding on the home router does not help because the relevant NAT is upstream at the ISP.

A VPS with a public address and a WireGuard tunnel can relay the traffic. It receives torrent connections on a port range and forwards them through the tunnel to the home server. To peers, the home server is then reachable at the VPS's public address.

Padavan is an open-source firmware derived from the GPL source ASUS released for the RT-N56U router. It targets MediaTek and Ralink SoCs: RT3883, MT7620, MT7621, and MT7628. The upstream repository on BitBucket last received updates in 2018. A fork on GitLab carries current development.

A prebuilt image targets one board and feature set. Building from source lets you match the device and select the features to compile. This post builds firmware for the MI-NANO router, whose official firmware is old and has no IPv6 support.

The Xiaomi Router Nano is a MediaTek MT7628 router. Stock MiWiFi accepts only signed updates and exposes no shell. Replacing the bootloader lets it run OpenWrt or Padavan.

Remote LAN access lets devices reach a private network from anywhere. ZeroTier uses a virtual L2 network with P2P paths. Tailscale builds on WireGuard with NAT traversal. Cloudflare Tunnel uses a reverse proxy model.

Default Linux kernel parameters target general-purpose workloads. Servers handling high traffic, many connections, or heavy I/O need tuning. This guide covers the sysctl parameters that matter and why.

Shadowsocks-libev is an encrypted SOCKS5 proxy. It does not tunnel a whole network stack the way a VPN does. The client exposes a local SOCKS5 port that applications point at, and the server relays each connection to its destination over an encrypted link. The stream carries no recognizable protocol handshake, which is why it appears as random bytes to an observer. The usual topology puts the client behind a censoring network and the server on an overseas VPS.

This post covers the libev implementation on Debian-family systems. The Chinese censor does more than watch traffic passively. It actively probes suspected servers, and a confirmed Shadowsocks server has its IP blocked in mainland China. Cipher choice determines how long a server lasts, not whether it is invulnerable.

Trojan, from the trojan-gfw project, is a proxy protocol that uses TLS with a valid certificate on a real domain. Its traffic resembles ordinary HTTPS browsing.

The server fronts a web server with ordinary content. A probe receives that website instead of a dead end.