esp32free80211 | Send arbitrary IEEE 802.11 frames with Espressif 's ESP32

esp32free80211 is a C library typically used in Internet of Things (IoT), Arduino applications. esp32free80211 has no bugs, it has no vulnerabilities and it has low support. You can download it from GitHub.

Even though Espressif open sourced their IoT Development Framework, the underlying esp32-wifi-lib remains closed source and sparsely documented. Since I still wanted to be able to send arbitrary IEEE 802.11 data frames, I took a look at the ieee80211_freedom_output function in ieee80211_output.o in libnet80211.a. By reverse engineering the assembly code I was able to find a workaround / hack that makes it possible to use ieee80211_freedom_output and force the ESP32 to send data or management frames with custom data. This functionality can be useful in various ways, e.g. for mesh networking, unidirectional long-distance communication or low-overhead data transmission. It can, however, be abused for spamming large numbers of invalid SSIDs, jamming WiFi networks or sending deauthentication frames in order to sniff SSIDs of hidden wireless networks. Please be advised that such usage is morally doubtful at best and illegal at worst. Use this at your own risk.