TCP is a connection oriented protocol. The socket connection will follow the TCP 3- way handshake to establish the connection.  In This Article, we take a look at a simple server and client example. The Internet IPv4 domain will be considered for the below example. The Stream socket will follow the below connection establishment process […]

The Different Socket Communication APIs that need to be understood for setting up a socket communication link are  Socket API The Socket API allows the creation of a socket and creates a file descriptor which is returned to the application requesting the same. The Socket API is provided below domain – The domain parameter indicates […]

A socket is a logical communication End-point.  It is a software interface that provides a means of communicating between two networking devices or between two processes running on the same device (Unix Sockets). The most popular analogy i have come across for a socket and quote the same is to “look at a socket as […]

A kernel module is loaded into kernel space. In case any specific value needs to be sent to the Kernel module during initialization or  dynamically at run-time, a method needs to be provided which will achieve the same. One such method to achieve the above requirement is the “module_param” macro. The “module_param” macro takes in […]

The WEP MPDU (MAC Protocol Data Unit) Format is shown below Key ID (2) bits – used to select the WEP key index – when Key-mapping keys are used the Key Id field is ignored IV – initialization vector ICV – integrity check value – calculated over the MPDU plaintext data The WEP encapsulation and […]

The WEP decapsulation is pictorially depicted below FIG Courtesy: 802.11 Standard WEP follows the below procedure to decrypt the received 802.11 WEP encrypted frame. WEP extracts the initialization vector (IV) and Key ID from the received packet to obtain the relevant WEP key. If Key-mapping keys are used, then the Key-mapping key will be used […]

The below wireless captures depict the packet handshake that ensues and is described in the article <Associating to an Access Point>. The example chosen below is for an open system – no security profile Station sends a Probe request Access Point responds by sending a probe response The WLAN Station device sends an 802.11 Authentication […]

The Beacon Frame format is as provided below: FIG Courtesy: 802.11 Wireless Networks: The Definitive Guide, 2nd Edition As can be seen from the pictorial representation above – the beacon frame consists of mandatory fields and optional fields. The Mandatory fields are those fields that are required for the proper working of the network. Optional […]

The WEP Encapsulation is shown pictorially below Fig Courtesy: 802.11 Standard The WEP encryption algorithm is ARC4 stream cipher provided by RSA Security Inc. The ARC4 cipher uses a pseudo-random number generator (PRNG) to generate a key-stream. This Key-stream is exclusive OR’ed with the plain text data to obtain the encrypted text. The exclusive OR […]

Traffic Indication Map (TIM) is an Information element and is part of the Beacon frame that is sent out by the Access Point at regular intervals. The TIM Information element provides information on the current DTIM count and DTIM period and also provides information on whether Buffered Multicast/Broadcast Data or unicast data for different 802.11 […]