WPS (Wi-Fi Protected Setup)

Wi-Fi Protected Setup (WPS; originally Wi-Fi Simple Config) is a computing standard that attempts to allow easy establishment of a secure wireless home network.

WPS Supports four usage modes aimed at a home network user adding a new device to the network:

1.PIN Method, in which a personal identification number (PIN) has to be read from either a sticker or the display on the new wireless device. This PIN must then be entered at the "representant" of the network, usually the access point of the network. Alternately, a PIN on the Access Point may be entered into the new device. The PIN Method is the mandatory baseline mode; every Wi-Fi Protected Setup certified product must support it.

2.Push-Button-Method, in which the user simply has to push a button, either an actual or virtual one, on both the access point (or a registrar of the network) and the new wireless client device. Support of this mode is mandatory for access points and optional for connecting devices.

3.Near-Field-Communication Method, in which the user simply has to bring the new client close to the access point to allow a near field communication between the devices. NFC Forum compliant RFID tags can also be used. Support of this mode is optional.

4.USB Method, in which the user uses a USB flash drive to transfer data between the new client device and the access point of the network. Support of this mode is optional, but deprecated.
The last two modes are usually referred as out-of-band methods as there is a transfer of information by a channel other than the Wi-Fi channel itself. Only the first two modes are currently covered by the Wi-Fi Protected Setup certification.

Basic Components in WPS network:

1.Registrar: A device with the authority to issue and revoke credentials to a network. A registrar may be integrated into a wireless access point (AP), or it may be separate from the AP.
2.Enrollee: A device seeking to join a wireless network.
3.AP: An AP functioning as a proxy between a registrar and an enrollee.

Basic scenario that involves AP with internal registrar and STA:

1.AP with internal registrar capabilities configures an Enrollee Station (STA). A descriptive information is transferred through a new Information Element (IE) that is added to the beacon, probe response and optionally to the probe request and association request/response messages. After the identification of the device's capabilities on both ends, a human trigger (Software/ Hardware Push button/PIN) is used to initiate the actual session of the protocol.

2.The session consists of 8 EAP request/response messages will be exchanged on the wireless medium between AP and STA, upon on a successful session, a configuration message (sent to enrolle) to indicate the protocol is done ending with the AP disassociating from the STA .

3.STA waits to reconnect with its new configuration (handed to it by the AP just before).

Overview of wpa_cli

Wpa_cli:

The wpa_cli utility is a text-based front-end program for interacting with wpa_supplicant. You can use it to query the current status, change the configuration, trigger events, and request interactive user input. 
 

Prerequisites to using wpa_cli:

A working wireless interface with wpa_supplicant running on it
The wpa_cli utility can show the current authentication status, selected security mode, dot11 and dot1x MIBs, etc. In addition, it can configure some variables like EAPOL state machine parameters and trigger events like reassociation and IEEE 802.1X logoff/logon. 

The wpa_cli utilities supports interactive and command-line modes. Both modes share the same command set, and the main difference is in interactive mode providing access to unsolicited messages (event messages, user name/password requests).


Interactive mode is started when wpa_cli is executed without any parameters on the command line. Commands are then entered from the controlling terminal in response to the wpa_cli prompt.
In command line mode, the same commands are entered as command line arguments.

Syntax:

wpa_cli  [-p path to ctrl sockets] 
         [-i ifname] 
         [-hvB] [-a action file] 
         [-P pid file] [command ... ]

Options:

-p path

Change the path where control sockets should be found.
Eg:wpa_cli -p /var/run/ctrl_interface
 

-i ifname

Specify the interface that is being configured. By default, choose the first interface found with a control socket in the socket path. 
Eg: wpa_cli -iwlan0 

-h

Help. Show a usage message.

-v

Show version information. 

-B

Run as a daemon in the background.

-a file

Run in daemon mode executing the action file based on events from wpa_supplicant. The specified file will be executed with the first argument set to the interface name, and the second to CONNECT or DISCONNECT, depending on the event.

-P file

Set the location of the PID file.

command

Run a command

  Eg: p2p_find, p2p_connect, p2p_group_add, p2p_group_remove, p2p_peer, p2p_peers, all_sta e.t.c.

Overview of WPA_Supplicant

WPA_Supplicant:

wpa_supplicant is a WPA Supplicant for Linux, BSD, Mac OS X, and Windows with support for WPA and WPA2 (IEEE 802.11i / RSN). It is suitable for both desktop/laptop computers and embedded systems.

wpa_supplicant is designed to be a "daemon" program that runs in the background and acts as the backend component controlling the wireless connection. wpa_supplicant supports separate frontend programs and a text-based frontend (wpa_cli) and a GUI (wpa_gui) are included with wpa_supplicant.

wpa_supplicant implements a control interface that can be used by external programs to control the operations of the wpa_supplicant daemon and to get status information and event notifications.

wpa_supplicant was designed to be portable for different drivers and operating systems. Hopefully, support for more wlan cards and OSes will be added in the future.

Before wpa_supplicant can do its work, the network interface must be available. That means that the physical device must be present and enabled, and the driver for the device must have be loaded. Note, however, that the -w option of the wpa_supplicant daemon instructs the daemon to continue to run and to wait for the interface to become available. Without the -w option, the daemon will exit immediately if the device isn't already available.

The wpa_supplicant utility is an implementation of the WPA Supplicant component, i.e., the part that runs in the client stations. It implements WPA key negotiation with a WPA Authenticator and EAP authentication with Authentication Server. In addition, it controls the roaming and IEEE 802.11 authentication/association of the wireless LAN driver.

After wpa_supplicant has configured the network device, higher level configuration such as DHCP may proceed.
The following steps are used when associating with an AP using WPA:

1. wpa_supplicant requests the driver to scan neighboring BSSes
2. wpa_supplicant selects a BSS based on its configuration
3. wpa_supplicant requests the driver to associate with the chosen BSS
4. If WPA-EAP: integrated IEEE 802.1X Supplicant or external Xsupplicant completes EAP authentication with the authentication server (proxied by the Authenticator in the AP)
5. If WPA-EAP: master key is received from the IEEE 802.1X Supplicant
6. If WPA-PSK: wpa_supplicant uses PSK as the master session key
7. wpa_supplicant completes WPA 4-Way Handshake and Group Key Handshake with the Authenticator (AP)
8. wpa_supplicant configures encryption keys for unicast and broadcast
9. normal data packets can be transmitted and received 
   
   

   Syntax:

   wpa_supplicant [-BddehLqqvw] [-iifname]  
                  [-cconfig file]  
                  [-Ddriver]

   Options:

   -p path

   Change the path where control sockets should be found.

   -i ifname

   Specify the interface that is being configured. By default, choose the first interface found with a control socket in the socket path.

   -h

   Help. Show a usage message.

   -v

   Show version information.

   -B

   Run as a daemon in the background.

   -a file

   Run in daemon mode executing the action file based on events from wpa_supplicant. The specified file will be executed with the first argument set to interface name and second to "CONNECT" or "DISCONNECT" depending on the event. This can be used

   -P file

   Set the location of the PID file.

   command

   Run a command. The available commands are listed in the next section.

   The following commands are available:

   -B

   Run daemon in the background.

   -i ifname

   Interface to listen on.

   -c filename

   Path to configuration file.

   -D driver

   Driver to use. See the available options below.

   -d

   Increase debugging verbosity (-dd even more).

   -K

   Include keys (passwords, etc.) in debug output.

   -t

   Include timestamp in debug messages.

   -e

   Use external IEEE 802.1X Supplicant (e.g., xsupplicant) (this disables the internal Supplicant).

   -h

   Help. Show a usage message.

   -L

   Show license (GPL and BSD).

   -q

   Decrease debugging verbosity (-qq even less).

   -v

   Show version.

   -w

   Wait for the interface to be added, if needed. Normally, wpa_supplicant exits if the interface isn't there yet.

   -N

   Start describing new interface.

   
   

IEEE 802 Wireless Standards:

The IEEE 802 Standard comprises a family of networking standards that cover the physical layer specifications of technologies from Ethernet to wireless. IEEE 802 is subdivided into 22 parts that cover the physical and data-link layers of networking. 

 All the 802.11 specifications use the Ethernet protocol and Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) for path sharing. The original modulation used in 802.11 was phase-shift keying (PSK). However, other schemes, such as complementary code keying (CCK), are used in some of the newer specifications. The newer modulation methods provide higher data speed and reduced vulnerability to interference.

802	Overview	Basics of physical and logical networking concepts.
802.1	Bridging	LAN/MAN bridging and management. Covers management and the lower sub-layers of OSI Layer 2, including MAC-based bridging (Media Access Control), virtual LANs and port-based access control.
802.2	Logical Link	Commonly referred to as the LLC or Logical Link Control specification. The LLC is the top sub-layer in the data-link layer, OSI Layer 2. Interfaces with the network Layer 3.
802.3	Ethernet	"Grandaddy" of the 802 specifications. Provides asynchronous networking using "carrier sense, multiple access with collision detect" (CSMA/CD) over coax, twisted-pair copper, and fiber media. Current speeds range from 10 Mbps to 10 Gbps.
802.4	Token Bus	Disbanded
802.5	Token Ring	The original token-passing standard for twisted-pair, shielded copper cables. Supports copper and fiber cabling from 4 Mbps to 100 Mbps. Often called "IBM Token-Ring."
802.6	Distributed queue dual bus (DQDB)	"Superseded **Revision of 802.1D-1990 edition (ISO/IEC 10038). 802.1D incorporates P802.1p and P802.12e. It also incorporates and supersedes published standards 802.1j and 802.6k. Superseded by 802.1D-2004."
802.7	Broadband LAN Practices	Withdrawn Standard. Withdrawn Date: Feb 07, 2003. No longer endorsed by the IEEE.
802.8	Fiber Optic Practices	Withdrawn PAR. Standards project no longer endorsed by the IEEE.
802.9	Integrated Services LAN	Withdrawn PAR. Standards project no longer endorsed by the IEEE.
802.10	Interoperable LAN security	Superseded **Contains: IEEE Std 802.10b-1992.
802.11	Wi-Fi	Wireless LAN Media Access Control and Physical Layer specification. 802.11a,b,g,etc. are amendments to the original 802.11 standard. Products that implement 802.11 standards must pass tests and are referred to as "Wi-Fi certified."
802.11a		·         Specifies a PHY that operates in the 5 GHz U-NII band in the US - initially 5.15-5.35 AND 5.725-5.85 - since expanded to additional frequencies ·         Uses Orthogonal Frequency-Division Multiplexing ·         Enhanced data speed to 54 Mbps ·         Ratified after 802.11b
802.11b		·         Enhancement to 802.11 that added higher data rate modes to the DSSS (Direct Sequence Spread Spectrum) already defined in the original 802.11 standard ·         Boosted data speed to 11 Mbps ·         22 MHz Bandwidth yields 3 non-overlaping channels in the frequency range of 2.400 GHz to 2.4835 GHz ·         Beacons at 1 Mbps, falls back to 5.5, 2, or 1 Mbps from 11 Mbps max.
802.11d		·         Enhancement to 802.11a and 802.11b that allows for global roaming ·         Particulars can be set at Media Access Control (MAC) layer
802.11e		·         Enhancement to 802.11 that includes quality of service (QoS) features ·         Facilitates prioritization of data, voice, and video transmissions
802.11g		·         Extends the maximum data rate of WLAN devices that operate in the 2.4 GHz band, in a fashion that permits interoperation with 802.11b devices ·         Uses OFDM Modulation (Orthogonal FDM) ·         Operates at up to 54 megabits per second (Mbps), with fall-back speeds that include the "b" speeds
802.11h		·         Enhancement to 802.11a that resolves interference issues ·         Dynamic frequency selection (DFS) ·         Transmit power control (TPC)
802.11i		·         Enhancement to 802.11 that offers additional security for WLAN applications ·         Defines more robust encryption, authentication, and key exchange, as well as options for key caching and pre-authentication
802.11j		·         Japanese regulatory extensions to 802.11a specification ·         Frequency range 4.9 GHz to 5.0 GHz
802.11k		·         Radio resource measurements for networksusing 802.11 family specifications
802.11m		·         Maintenance of 802.11 family specifications ·         Corrections and amendments to existing documentation
802.11n		·         Higher-speed standards -- under development ·         Several competing and non-compatible technologies; often called "pre-n" ·         Top speeds claimed of 108, 240, and 350+ MHz ·         Competing proposals come from the groups, EWC, TGn Sync, and WWiSE and are all variations based on MIMO (multiple input, multiple output)
802.11x		·         Mis-used "generic" term for 802.11 family specifications
802.12	Demand Priority	Increases Ethernet data rate to 100 Mbps by controlling media utilization.
802.13	Not used	Not used
802.14	Cable modems	Withdrawn PAR. Standards project no longer endorsed by the IEEE.
802.15	Wireless Personal Area Networks	Communications specification that was approved in early 2002 by the IEEE for wireless personal area networks (WPANs).
802.15.1	Bluetooth	Short range (10m) wireless technology for cordless mouse, keyboard, and hands-free headset at 2.4 GHz.
802.15.3a	UWB	Short range, high-bandwidth "ultra wideband" link
802.15.4	ZigBee	Short range wireless sensor networks
802.15.5	Mesh Network	·         Extension of network coverage without increasing the transmit power or the receiver sensitivity ·         Enhanced reliability via route redundancy ·         Easier network configuration - Better device battery life
802.16	Wireless Metropolitan Area Networks	This family of standards covers Fixed and Mobile Broadband Wireless Access methods used to create Wireless Metropolitan Area Networks (WMANs.) Connects Base Stations to the Internet using OFDM in unlicensed (900 MHz, 2.4, 5.8 GHz) or licensed (700 MHz, 2.5 – 3.6 GHz) frequency bands. Products that implement 802.16 standards can undergoWiMAX certification testing.
802.17	Resilient Packet Ring	IEEE working group description
802.18	Radio Regulatory TAG	IEEE 802.18 standards committee
802.19	Coexistence	IEEE 802.19 Coexistence Technical Advisory Group
802.20	Mobile Broadband Wireless Access	IEEE 802.20 mission and project scope
802.21	Media Independent Handoff	IEEE 802.21 mission and project scope
802.22	Wireless Regional Area Network	IEEE 802.22 mission and project scope

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