ESPTerm is web terminal emulator on the ESP8266. It starts a WiFi AP by default, and works from mobile browser, so you connect a flashed ESP with 4 wires to openwrt uart and than can manage it from the mobile phone. Due to cheapness you can leave it inside.
Online demo: https://espterm.github.io/term.html
Just thought that everyone should know about this project, which very suitable for OpenWRT.
How is this related to OpenWrt?
Was previously using esp-link for this... It's a nice solid solution for cable-less serial. ( allows programming over wifi )... Or cable less gpio interaction ( reboot the router etc. )
How does it differ from esp-link? In what ways is it better / different?
This is risky... Are you sure this would not fry/droop some router models ttl vcc circuitry? How many routers have you tested/powered an esp from the serial power?
Esp-link looks complicated, and without web terminal. ESPTerm is simple, terminal only tool.
I see nothing risky here. Most of the routers that I saw were 3.3V and I don't remember no one with 5V. ESP8266 is 3.3V with 5V tolerant and on average draws around 100mA:
Have you ever broken network connectivity?
Sorry, I had not understood the part where you explain the use case. It all makes sense, and now it looks like a great project.
These devices could be left installed on the router, as an out-of-band channel, and would be great as a recovery tool.
I would be careful about feeding 5v to those, however.
(:
As I've badly explained ESP8266 uses is 3.3V for power and ttl lines are 5V tolerant, so you can't power it with 5V without voltage regulator. (But there are ESP8266 modules with 5V->3V regulator on the board.)