Network Security Tools

Using AirJack

AirJack is a device driver supporting arbitrary packet capture and creation, and although you can use libpcap with AirJack to capture packets, you also can create packets using the Linux low-level sockets interface. To show you how to use AirJack for packet injection, we will use a simple reinjection tool called reinject .

Overview of reinject

reinject is designed to capture a packet from the interface using libpcap, and then to reinject the captured packet into the existing wireless conversation. This type of tool can be extended for use in attacking WEP encryption with a static key by capturing a packet that generates a response (i.e., an ARP request) and replaying it on the encrypted network many times to capture the encrypted replies (i.e., ARP replies). This works on networks with static WEP keys due to the lack of replay protection in the initial 802.11 standards. In conjunction with other attacks on WEP encryption, this approach can make it easier to determine a static WEP key.

reinject is a very simple tool in that it does not have the ability to change the channel on which it is capturing packets or sending data. AirJack ships with several examples that show you how to change channels within your tool.

Using sockets with AirJack

To open the AirJack interface for packet injection, we first need to create a socket, as shown in Example 11-11. The socket function is documented in the Linux manpages in Section 2 (man 2 socket). In this example we open the socket ...