Analysis of injection capabilities and media access of IEEE 802.11 hardware in monitor mode

Support for monitor mode and frame injection is key to setup wireless testbeds based on IEEE802.11 hardware that allow implementation and evaluation of custom link-layer protocols, e.g. network coding, opportunistic routing, and software defined networking. While monitor mode is a widely supported feature, frame injection seems to be limited to legacy data rates in the 2.4GHz band if supported at all. In addition we found that many devices do not adhere to basic media access procedures when operating in monitor mode, which has severe effects in contended environments. In this paper we investigate the injection capabilities and MAC procedures of different chipsets. To enable IEEE802.11n rates and 5GHz, we developed a series of small patches, which mostly apply to the generic part of the Linux drivers. In addition we present a command line tool for automated evaluation of injection capabilities of different devices. The patches, tools, and the underlying injection library used in this paper are publicly available [1].