NOTE: shadowsocks-libev is included in OpenWrt up to version 23.05 and dropped thereafter (see this pull request).
shadowsocks is a fast tunnel proxy that helps you bypass firewalls.
Here's a summary on how to install and setup shadowsocks on a fresh OpenWrt 19.06 installation, (taken from this forum post)
You need to install the following packages:
opkg install shadowsocks-libev-ss-local shadowsocks-libev-ss-redir shadowsocks-libev-ss-rules shadowsocks-libev-ss-tunnel
And if you need the Luci web interface also:
opkg install luci-app-shadowsocks-libev
In the Luci Web UI, head to Services → Shadowsocks-libev → Remote Servers if going from CLI the config file is /etc/config/shadowsocks-libev
Edit the existing sss0 server (or add a new one). Set at least IP, port, method and password, and don't forget to untick the Disable checkbox.
The simplest recipe is to forward all traffic through the tunnel. Follow the steps outlined in the readme file under Recipes > forward all
This must be done via command line according to the instructions in in the readme file under Recipes > forward all