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diff --git a/wpa_supplicant/README-WPS b/wpa_supplicant/README-WPS new file mode 100644 index 0000000000000..7fd358dbec667 --- /dev/null +++ b/wpa_supplicant/README-WPS @@ -0,0 +1,184 @@ +wpa_supplicant and Wi-Fi Protected Setup (WPS) +============================================== + +This document describes how the WPS implementation in wpa_supplicant +can be configured and how an external component on the client (e.g., +management GUI) is used to enable WPS enrollment and registrar +registration. + + +Introduction to WPS +------------------- + +Wi-Fi Protected Setup (WPS) is a mechanism for easy configuration of a +wireless network. It allows automated generation of random keys (WPA +passphrase/PSK) and configuration of an access point and client +devices. WPS includes number of methods for setting up connections +with PIN method and push-button configuration (PBC) being the most +commonly deployed options. + +While WPS can enable more home networks to use encryption in the +wireless network, it should be noted that the use of the PIN and +especially PBC mechanisms for authenticating the initial key setup is +not very secure. As such, use of WPS may not be suitable for +environments that require secure network access without chance for +allowing outsiders to gain access during the setup phase. + +WPS uses following terms to describe the entities participating in the +network setup: +- access point: the WLAN access point +- Registrar: a device that control a network and can authorize + addition of new devices); this may be either in the AP ("internal + Registrar") or in an external device, e.g., a laptop, ("external + Registrar") +- Enrollee: a device that is being authorized to use the network + +It should also be noted that the AP and a client device may change +roles (i.e., AP acts as an Enrollee and client device as a Registrar) +when WPS is used to configure the access point. + + +More information about WPS is available from Wi-Fi Alliance: +http://www.wi-fi.org/wifi-protected-setup + + +wpa_supplicant implementation +----------------------------- + +wpa_supplicant includes an optional WPS component that can be used as +an Enrollee to enroll new network credential or as a Registrar to +configure an AP. The current version of wpa_supplicant does not +support operation as an external WLAN Management Registrar for adding +new client devices or configuring the AP over UPnP. + + +wpa_supplicant configuration +---------------------------- + +WPS is an optional component that needs to be enabled in +wpa_supplicant build configuration (.config). Here is an example +configuration that includes WPS support and Linux wireless extensions +-based driver interface: + +CONFIG_DRIVER_WEXT=y +CONFIG_EAP=y +CONFIG_WPS=y + + +WPS needs the Universally Unique IDentifier (UUID; see RFC 4122) for +the device. This is configured in the runtime configuration for +wpa_supplicant (if not set, UUID will be generated based on local MAC +address): + +# example UUID for WPS +uuid=12345678-9abc-def0-1234-56789abcdef0 + +The network configuration blocks needed for WPS are added +automatically based on control interface commands, so they do not need +to be added explicitly in the configuration file. + +WPS registration will generate new network blocks for the acquired +credentials. If these are to be stored for future use (after +restarting wpa_supplicant), wpa_supplicant will need to be configured +to allow configuration file updates: + +update_config=1 + + + +External operations +------------------- + +WPS requires either a device PIN code (usually, 8-digit number) or a +pushbutton event (for PBC) to allow a new WPS Enrollee to join the +network. wpa_supplicant uses the control interface as an input channel +for these events. + +If the client device has a display, a random PIN has to be generated +for each WPS registration session. wpa_supplicant can do this with a +control interface request, e.g., by calling wpa_cli: + +wpa_cli wps_pin any + +This will return the generated 8-digit PIN which will then need to be +entered at the Registrar to complete WPS registration. At that point, +the client will be enrolled with credentials needed to connect to the +AP to access the network. + + +If the client device does not have a display that could show the +random PIN, a hardcoded PIN that is printed on a label can be +used. wpa_supplicant is notified this with a control interface +request, e.g., by calling wpa_cli: + +wpa_cli wps_pin any 12345670 + +This starts the WPS negotiation in the same way as above with the +generated PIN. + + +If the client design wants to support optional WPS PBC mode, this can +be enabled by either a physical button in the client device or a +virtual button in the user interface. The PBC operation requires that +a button is also pressed at the AP/Registrar at about the same time (2 +minute window). wpa_supplicant is notified of the local button event +over the control interface, e.g., by calling wpa_cli: + +wpa_cli wps_pbc + +At this point, the AP/Registrar has two minutes to complete WPS +negotiation which will generate a new WPA PSK in the same way as the +PIN method described above. + + +If the client wants to operation in the Registrar role to configure an +AP, wpa_supplicant is notified over the control interface, e.g., with +wpa_cli: + +wpa_cli wps_reg <AP BSSID> <AP PIN> +(example: wpa_cli wps_reg 02:34:56:78:9a:bc 12345670) + + +Scanning +-------- + +Scan results ('wpa_cli scan_results' or 'wpa_cli bss <idx>') include a +flags field that is used to indicate whether the BSS support WPS. If +the AP support WPS, but has not recently activated a Registrar, [WPS] +flag will be included. If PIN method has been recently selected, +[WPS-PIN] is shown instead. Similarly, [WPS-PBC] is shown if PBC mode +is in progress. GUI programs can use these as triggers for suggesting +a guided WPS configuration to the user. In addition, control interface +monitor events WPS-AP-AVAILABLE{,-PBC,-PIN} can be used to find out if +there are WPS enabled APs in scan results without having to go through +all the details in the GUI. These notification could be used, e.g., to +suggest possible WPS connection to the user. + + +wpa_gui +------- + +wpa_gui-qt4 directory contains a sample GUI that shows an example of +how WPS support can be integrated into the GUI. Its main window has a +WPS tab that guides user through WPS registration with automatic AP +selection. In addition, it shows how WPS can be started manually by +selecting an AP from scan results. + + +Credential processing +--------------------- + +By default, wpa_supplicant processes received credentials and updates +its configuration internally. However, it is possible to +control these operations from external programs, if desired. + +This internal processing can be disabled with wps_cred_processing=1 +option. When this is used, an external program is responsible for +processing the credential attributes and updating wpa_supplicant +configuration based on them. + +Following control interface messages are sent out for external programs: + +WPS-CRED-RECEIVED <hexdump of Credential attribute(s)> +For example: +<2>WPS-CRED-RECEIVED 100e006f10260001011045000c6a6b6d2d7770732d74657374100300020020100f000200081027004030653462303435366332363666653064333961643135353461316634626637313234333761636664623766333939653534663166316230323061643434386235102000060266a0ee1727 |