wpa_supplicant and Wi-Fi P2P ============================ This document describes how the Wi-Fi P2P 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 Wi-Fi P2P ------------------------- TODO More information about Wi-Fi P2P is available from Wi-Fi Alliance: http://www.wi-fi.org/Wi-Fi_Direct.php wpa_supplicant implementation ----------------------------- TODO wpa_supplicant configuration ---------------------------- Wi-Fi P2P is an optional component that needs to be enabled in the wpa_supplicant build configuration (.config). Here is an example configuration that includes Wi-Fi P2P support and Linux nl80211 -based driver interface: CONFIG_DRIVER_NL80211=y CONFIG_CTRL_IFACE=y CONFIG_P2P=y CONFIG_AP=y CONFIG_WPS=y In run-time configuration file (wpa_supplicant.conf), some parameters for P2P may be set. In order to make the devices easier to recognize, device_name and device_type should be specified. For example, something like this should be included: ctrl_interface=/var/run/wpa_supplicant device_name=My P2P Device device_type=1-0050F204-1 wpa_cli ------- Actual Wi-Fi P2P operations are requested during runtime. These can be done for example using wpa_cli (which is described below) or a GUI like wpa_gui-qt4. wpa_cli starts in interactive mode if no command string is included on the command line. By default, it will select the first network interface that it can find (and that wpa_supplicant controls). If more than one interface is in use, it may be necessary to select one of the explicitly by adding -i argument on the command line (e.g., 'wpa_cli -i wlan1'). Most of the P2P operations are done on the main interface (e.g., the interface that is automatically added when the driver is loaded, e.g., wlan0). When using a separate virtual interface for group operations (e.g., wlan1), the control interface for that group interface may need to be used for some operations (mainly WPS activation in GO). This may change in the future so that all the needed operations could be done over the main control interface. Device Discovery p2p_find [timeout in seconds] [type=<social|progressive>] \ [dev_id=<addr>] [dev_type=<device type>] \ [delay=<search delay in ms>] The default behavior is to run a single full scan in the beginning and then scan only social channels. type=social will scan only social channels, i.e., it skips the initial full scan. type=progressive is like the default behavior, but it will scan through all the channels progressively one channel at the time in the Search state rounds. This will help in finding new groups or groups missed during the initial full scan. The optional dev_id option can be used to specify a single P2P peer to search for. The optional delay parameter can be used to request an extra delay to be used between search iterations (e.g., to free up radio resources for concurrent operations). The optional dev_type option can be used to specify a single device type (primary or secondary) to search for, e.g., "p2p_find dev_type=1-0050F204-1". p2p_listen [timeout in seconds] Start Listen-only state (become discoverable without searching for other devices). Optional parameter can be used to specify the duration for the Listen operation in seconds. This command may not be of that much use during normal operations and is mainly designed for testing. It can also be used to keep the device discoverable without having to maintain a group. p2p_stop_find Stop ongoing P2P device discovery or other operation (connect, listen mode). p2p_flush Flush P2P peer table and state. Group Formation p2p_prov_disc <peer device address> <display|keypad|pbc> [join|auto] Send P2P provision discovery request to the specified peer. The parameters for this command are the P2P device address of the peer and the desired configuration method. For example, "p2p_prov_disc 02:01:02:03:04:05 display" would request the peer to display a PIN for us and "p2p_prov_disc 02:01:02:03:04:05 keypad" would request the peer to enter a PIN that we display. The optional "join" parameter can be used to indicate that this command is requesting an already running GO to prepare for a new client. This is mainly used with "display" to request it to display a PIN. The "auto" parameter can be used to request wpa_supplicant to automatically figure out whether the peer device is operating as a GO and if so, use join-a-group style PD instead of GO Negotiation style PD. p2p_connect <peer device address> <pbc|pin|PIN#> [display|keypad] [persistent|persistent=<network id>] [join|auth] [go_intent=<0..15>] [freq=<in MHz>] [ht40] [vht] [provdisc] Start P2P group formation with a discovered P2P peer. This includes optional group owner negotiation, group interface setup, provisioning, and establishing data connection. The <pbc|pin|PIN#> parameter specifies the WPS provisioning method. "pbc" string starts pushbutton method, "pin" string start PIN method using an automatically generated PIN (which will be returned as the command return code), PIN# means that a pre-selected PIN can be used (e.g., 12345670). [display|keypad] is used with PIN method to specify which PIN is used (display=dynamically generated random PIN from local display, keypad=PIN entered from peer display). "persistent" parameter can be used to request a persistent group to be formed. The "persistent=<network id>" alternative can be used to pre-populate SSID/passphrase configuration based on a previously used persistent group where this device was the GO. The previously used parameters will then be used if the local end becomes the GO in GO Negotiation (which can be forced with go_intent=15). "join" indicates that this is a command to join an existing group as a client. It skips the GO Negotiation part. This will send a Provision Discovery Request message to the target GO before associating for WPS provisioning. "auth" indicates that the WPS parameters are authorized for the peer device without actually starting GO Negotiation (i.e., the peer is expected to initiate GO Negotiation). This is mainly for testing purposes. "go_intent" can be used to override the default GO Intent for this GO Negotiation. "freq" can be used to set a forced operating channel (e.g., freq=2412 to select 2.4 GHz channel 1). "provdisc" can be used to request a Provision Discovery exchange to be used prior to starting GO Negotiation as a workaround with some deployed P2P implementations that require this to allow the user to accept the connection. p2p_group_add [persistent|persistent=<network id>] [freq=<freq in MHz>] [ht40] [vht] Set up a P2P group owner manually (i.e., without group owner negotiation with a specific peer). This is also known as autonomous GO. Optional persistent=<network id> can be used to specify restart of a persistent group. Optional freq=<freq in MHz> can be used to force the GO to be started on a specific frequency. Special freq=2 or freq=5 options can be used to request the best 2.4 GHz or 5 GHz band channel to be selected automatically. p2p_reject <peer device address> Reject connection attempt from a peer (specified with a device address). This is a mechanism to reject a pending GO Negotiation with a peer and request to automatically block any further connection or discovery of the peer. p2p_group_remove <group interface> Terminate a P2P group. If a new virtual network interface was used for the group, it will also be removed. The network interface name of the group interface is used as a parameter for this command. p2p_cancel Cancel an ongoing P2P group formation and joining-a-group related operation. This operations unauthorizes the specific peer device (if any had been authorized to start group formation), stops P2P find (if in progress), stops pending operations for join-a-group, and removes the P2P group interface (if one was used) that is in the WPS provisioning step. If the WPS provisioning step has been completed, the group is not terminated. p2p_remove_client <peer's P2P Device Address|iface=<interface address>> This command can be used to remove the specified client from all groups (operating and persistent) from the local GO. Note that the peer device can rejoin the group if it is in possession of a valid key. See p2p_set per_sta_psk command below for more details on how the peer can be removed securely. Service Discovery p2p_serv_disc_req Schedule a P2P service discovery request. The parameters for this command are the device address of the peer device (or 00:00:00:00:00:00 for wildcard query that is sent to every discovered P2P peer that supports service discovery) and P2P Service Query TLV(s) as hexdump. For example, p2p_serv_disc_req 00:00:00:00:00:00 02000001 schedules a request for listing all available services of all service discovery protocols and requests this to be sent to all discovered peers (note: this can result in long response frames). The pending requests are sent during device discovery (see p2p_find). There can be multiple pending peer device specific queries (each will be sent in sequence whenever the peer is found). This command returns an identifier for the pending query (e.g., "1f77628") that can be used to cancel the request. Directed requests will be automatically removed when the specified peer has replied to it. Service Query TLV has following format: Length (2 octets, little endian) - length of following data Service Protocol Type (1 octet) - see the table below Service Transaction ID (1 octet) - nonzero identifier for the TLV Query Data (Length - 2 octets of data) - service protocol specific data Service Protocol Types: 0 = All service protocols 1 = Bonjour 2 = UPnP 3 = WS-Discovery 4 = Wi-Fi Display For UPnP, an alternative command format can be used to specify a single query TLV (i.e., a service discovery for a specific UPnP service): p2p_serv_disc_req 00:00:00:00:00:00 upnp <version hex> <ST: from M-SEARCH> For example: p2p_serv_disc_req 00:00:00:00:00:00 upnp 10 urn:schemas-upnp-org:device:InternetGatewayDevice:1 Additional examples for queries: # list of all Bonjour services p2p_serv_disc_req 00:00:00:00:00:00 02000101 # list of all UPnP services p2p_serv_disc_req 00:00:00:00:00:00 02000201 # list of all WS-Discovery services p2p_serv_disc_req 00:00:00:00:00:00 02000301 # list of all Bonjour and UPnP services p2p_serv_disc_req 00:00:00:00:00:00 0200010102000202 # Apple File Sharing over TCP p2p_serv_disc_req 00:00:00:00:00:00 130001010b5f6166706f766572746370c00c000c01 # Bonjour SSTH (supported service type hash) p2p_serv_disc_req 00:00:00:00:00:00 05000101000000 # UPnP examples p2p_serv_disc_req 00:00:00:00:00:00 upnp 10 ssdp:all p2p_serv_disc_req 00:00:00:00:00:00 upnp 10 upnp:rootdevice p2p_serv_disc_req 00:00:00:00:00:00 upnp 10 urn:schemas-upnp-org:service:ContentDirectory:2 p2p_serv_disc_req 00:00:00:00:00:00 upnp 10 uuid:6859dede-8574-59ab-9332-123456789012 p2p_serv_disc_req 00:00:00:00:00:00 upnp 10 urn:schemas-upnp-org:device:InternetGatewayDevice:1 # Wi-Fi Display examples # format: wifi-display <list of roles> <list of subelements> p2p_serv_disc_req 00:00:00:00:00:00 wifi-display [source] 2,3,4,5 p2p_serv_disc_req 02:01:02:03:04:05 wifi-display [pri-sink] 3 p2p_serv_disc_req 00:00:00:00:00:00 wifi-display [sec-source] 2 p2p_serv_disc_req 00:00:00:00:00:00 wifi-display [source+sink] 2,3,4,5 p2p_serv_disc_req 00:00:00:00:00:00 wifi-display [source][pri-sink] 2,3,4,5 p2p_serv_disc_cancel_req <query identifier> Cancel a pending P2P service discovery request. This command takes a single parameter: identifier for the pending query (the value returned by p2p_serv_disc_req, e.g., "p2p_serv_disc_cancel_req 1f77628". p2p_serv_disc_resp Reply to a service discovery query. This command takes following parameters: frequency in MHz, destination address, dialog token, response TLV(s). The first three parameters are copied from the request event. For example, "p2p_serv_disc_resp 2437 02:40:61:c2:f3:b7 1 0300000101". This command is used only if external program is used to process the request (see p2p_serv_disc_external). p2p_service_update Indicate that local services have changed. This is used to increment the P2P service indicator value so that peers know when previously cached information may have changed. This is only needed when external service discovery processing is enabled since the commands to pre-configure services for internal processing will increment the indicator automatically. p2p_serv_disc_external <0|1> Configure external processing of P2P service requests: 0 (default) = no external processing of requests (i.e., internal code will process each request based on pre-configured services), 1 = external processing of requests (external program is responsible for replying to service discovery requests with p2p_serv_disc_resp). Please note that there is quite strict limit on how quickly the response needs to be transmitted, so use of the internal processing is strongly recommended. p2p_service_add bonjour <query hexdump> <RDATA hexdump> Add a local Bonjour service for internal SD query processing. Examples: # AFP Over TCP (PTR) p2p_service_add bonjour 0b5f6166706f766572746370c00c000c01 074578616d706c65c027 # AFP Over TCP (TXT) (RDATA=null) p2p_service_add bonjour 076578616d706c650b5f6166706f766572746370c00c001001 00 # IP Printing over TCP (PTR) (RDATA=MyPrinter._ipp._tcp.local.) p2p_service_add bonjour 045f697070c00c000c01 094d795072696e746572c027 # IP Printing over TCP (TXT) (RDATA=txtvers=1,pdl=application/postscript) p2p_service_add bonjour 096d797072696e746572045f697070c00c001001 09747874766572733d311a70646c3d6170706c69636174696f6e2f706f7374736372797074 # Supported Service Type Hash (SSTH) p2p_service_add bonjour 000000 <32-byte bitfield as hexdump> (note: see P2P spec Annex E.4 for information on how to construct the bitfield) p2p_service_del bonjour <query hexdump> Remove a local Bonjour service from internal SD query processing. p2p_service_add upnp <version hex> <service> Add a local UPnP service for internal SD query processing. Examples: p2p_service_add upnp 10 uuid:6859dede-8574-59ab-9332-123456789012::upnp:rootdevice p2p_service_add upnp 10 uuid:5566d33e-9774-09ab-4822-333456785632::upnp:rootdevice p2p_service_add upnp 10 uuid:1122de4e-8574-59ab-9322-333456789044::urn:schemas-upnp-org:service:ContentDirectory:2 p2p_service_add upnp 10 uuid:5566d33e-9774-09ab-4822-333456785632::urn:schemas-upnp-org:service:ContentDirectory:2 p2p_service_add upnp 10 uuid:6859dede-8574-59ab-9332-123456789012::urn:schemas-upnp-org:device:InternetGatewayDevice:1 p2p_service_del upnp <version hex> <service> Remove a local UPnP service from internal SD query processing. p2p_service_flush Remove all local services from internal SD query processing. Invitation p2p_invite [persistent=<network id>|group=<group ifname>] [peer=address] [go_dev_addr=address] [freq=<freq in MHz>] [ht40] [vht] [pref=<MHz>] Invite a peer to join a group (e.g., group=wlan1) or to reinvoke a persistent group (e.g., persistent=4). If the peer device is the GO of the persistent group, the peer parameter is not needed. Otherwise it is used to specify which device to invite. go_dev_addr parameter can be used to override the GO device address for Invitation Request should it be not known for some reason (this should not be needed in most cases). When reinvoking a persistent group, the GO device can specify the frequency for the group with the freq parameter. When reinvoking a persistent group, the P2P client device can use freq parameter to force a specific operating channel (or invitation failure if GO rejects that) or pref parameter to request a specific channel (while allowing GO to select to use another channel, if needed). Group Operations (These are used on the group interface.) wps_pin <any|address> <PIN> Start WPS PIN method. This allows a single WPS Enrollee to connect to the AP/GO. This is used on the GO when a P2P client joins an existing group. The second parameter is the address of the Enrollee or a string "any" to allow any station to use the entered PIN (which will restrict the PIN for one-time-use). PIN is the Enrollee PIN read either from a label or display on the P2P Client/WPS Enrollee. wps_pbc Start WPS PBC method (i.e., push the button). This allows a single WPS Enrollee to connect to the AP/GO. This is used on the GO when a P2P client joins an existing group. p2p_get_passphrase Get the passphrase for a group (only available when acting as a GO). p2p_presence_req [<duration> <interval>] [<duration> <interval>] Send a P2P Presence Request to the GO (this is only available when acting as a P2P client). If no duration/interval pairs are given, the request indicates that this client has no special needs for GO presence. The first parameter pair gives the preferred duration and interval values in microseconds. If the second pair is included, that indicates which value would be acceptable. This command returns OK immediately and the response from the GO is indicated in a P2P-PRESENCE-RESPONSE event message. Parameters p2p_ext_listen [<period> <interval>] Configure Extended Listen Timing. If the parameters are omitted, this feature is disabled. If the parameters are included, Listen State will be entered every interval msec for at least period msec. Both values have acceptable range of 1-65535 (with interval obviously having to be larger than or equal to duration). If the P2P module is not idle at the time the Extended Listen Timing timeout occurs, the Listen State operation will be skipped. The configured values will also be advertised to other P2P Devices. The received values are available in the p2p_peer command output: ext_listen_period=100 ext_listen_interval=5000 p2p_set <field> <value> Change dynamic P2P parameters p2p_set discoverability <0/1> Disable/enable advertisement of client discoverability. This is enabled by default and this parameter is mainly used to allow testing of device discoverability. p2p_set managed <0/1> Disable/enable managed P2P Device operations. This is disabled by default. p2p_set listen_channel <1/6/11> Set P2P Listen channel. This is mainly meant for testing purposes and changing the Listen channel during normal operations can result in protocol failures. p2p_set ssid_postfix <postfix> Set postfix string to be added to the automatically generated P2P SSID (DIRECT-<two random characters>). For example, postfix of "-testing" could result in the SSID becoming DIRECT-ab-testing. p2p_set per_sta_psk <0/1> Disabled(default)/enables use of per-client PSK in the P2P groups. This can be used to request GO to assign a unique PSK for each client during WPS provisioning. When enabled, this allow clients to be removed from the group securily with p2p_remove_client command since that client's PSK is removed at the same time to prevent it from connecting back using the old PSK. When per-client PSK is not used, the client can still be disconnected, but it will be able to re-join the group since the PSK it learned previously is still valid. It should be noted that the default passphrase on the GO that is normally used to allow legacy stations to connect through manual configuration does not change here, so if that is shared, devices with knowledge of that passphrase can still connect. set <field> <value> Set global configuration parameters which may also affect P2P operations. The format on these parameters is same as is used in wpa_supplicant.conf. Only the parameters listen here should be changed. Modifying other parameters may result in incorrect behavior since not all existing users of the parameters are updated. set uuid <UUID> Set WPS UUID (by default, this is generated based on the MAC address). set device_name <device name> Set WPS Device Name (also included in some P2P messages). set manufacturer <manufacturer> Set WPS Manufacturer. set model_name <model name> Set WPS Model Name. set model_number <model number> Set WPS Model Number. set serial_number <serial number> Set WPS Serial Number. set device_type <device type> Set WPS Device Type. set os_version <OS version> Set WPS OS Version. set config_methods <config methods> Set WPS Configuration Methods. set sec_device_type <device type> Add a new Secondary Device Type. set p2p_go_intent <GO intent> Set the default P2P GO Intent. Note: This value can be overridden in p2p_connect command and as such, there should be no need to change the default value here during normal operations. set p2p_ssid_postfix <P2P SSID postfix> Set P2P SSID postfix. set persistent_reconnect <0/1> Disable/enabled persistent reconnect for reinvocation of persistent groups. If enabled, invitations to reinvoke a persistent group will be accepted without separate authorization (e.g., user interaction). set country <two character country code> Set country code (this is included in some P2P messages). set p2p_search_delay <delay> Set p2p_search_delay which adds extra delay in milliseconds between concurrent search iterations to make p2p_find friendlier to concurrent operations by avoiding it from taking 100% of radio resources. The default value is 500 ms. Status p2p_peers [discovered] List P2P Device Addresses of all the P2P peers we know. The optional "discovered" parameter filters out the peers that we have not fully discovered, i.e., which we have only seen in a received Probe Request frame. p2p_peer <P2P Device Address> Fetch information about a known P2P peer. Group Status (These are used on the group interface.) status Show status information (connection state, role, use encryption parameters, IP address, etc.). sta Show information about an associated station (when acting in AP/GO role). all_sta Lists the currently associated stations. Configuration data list_networks Lists the configured networks, including stored information for persistent groups. The identifier in this list is used with p2p_group_add and p2p_invite to indicate which persistent group is to be reinvoked. remove_network <network id> Remove a network entry from configuration. wpa_cli action script --------------------- See examples/p2p-action.sh TODO: describe DHCP/DNS setup TODO: cross-connection