This is a proof of concept implementation of a WiFi NAT router on the esp8266. It can be used as range extender for an existing WiFi network. Throuput is reasonable, at least Youtube videos work faily well.
The esp acts as STA and as soft-AP and transparently forwards any IP traffic through it. As it uses NAT no routing entries are required neither on the network side nor on the connected stations. Stations are configured via DHCP in the 192.168.4.0/24 net and receive their DNS responder address from the existing WiFi network.
The router can be configured via a console interface and the config can be stored in flash. The router also allows for remote monitoring of the complete traffic, e.g. using Wireshark.
Possible use cases:
- Battery powered outdoor wifi range extender
- Temporary guest WiFi network for network that don't support multiple SSIDs
- WiFi-probe for observing IP-traffic of smartphones or IoT devices
To build it you will need the esp-open-sdk and an adaped version of the lwip TCP/IP-stack.
Sources and binaries can be found here: https://github.com/martin-ger/esp_wifi_repeater