Next, we will use airodump-ng to sniff the packet flow in the air in this aircrack tutorial. Note that the client and AP need to be in one channel to communicate. The aircrack developers created this brilliant tool with the ability to hop between channels and sniff packets. We will first use airomon-ng in this aircrack tutorial to create a promiscuous mode interface (mon0) to sniff the wireless network. No one can really tell that a hacker is sniffing the packets, since it all happens wirelessly. Sniffing the air is a simple and totally passive task.
In this aircrack tutorial, we will first sniff the air for packets. Cracking the WEP key Task No 1: Sniffing packets and collecting weak IVs floating in the air Sniffing out packets and collecting weak IVsģ.
This aircrack tutorial demonstrates WEP cracking in three steps:ġ. And this can be done with a toolkit called the aircrack-ng suite. The basic idea behind WEP cracking is to trace weak IVs in the air. Once the passkey is provided, the AP is accessible from the client, as shown in the figure below. When I connect my Blackberry Wi-Fi client to the AP, it asks for a passkey, here is the display: The cipher text will again be prepended with the same IV, chosen non-uniquely. This WEP key will perform an XOR operation with the data and CRC integrity and generate the cipher text. The 24bit IVs prefixed by the AP take the total to 64/128 bits. Note that the actual WEP key is 40/104 bits.
The three-byte IVs use two bits to define the encryption key in use. Here, my AP has the option to generate four keys based on a given passphrase. The data is prepended with an initialization vector (IV) field, which contains information about the encryption key in use.
Since it uses RC4 symmetric encryption, both client and AP use identical data encryption keys. WEP is defined in the 802.11 standards as a protocol for protecting authorized WLAN users from casual eavesdropping. Unfortunately, it isn’t, but is instead a mandatory field for any legitimate client to connect to an AP. It is commonly believed that disabling SSID broadcasts is a security measure. This aircrack tutorial will take you through the steps involved in cracking a WEP key using aircrack-ng. A WEP encryption key can be easily cracked using aircrack-ng.
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