471 lines
15 KiB
Plaintext
471 lines
15 KiB
Plaintext
wpa_supplicant and Hotspot 2.0
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==============================
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This document describe how the IEEE 802.11u Interworking and Wi-Fi
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Hotspot 2.0 (Release 1) implementation in wpa_supplicant can be
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configured and how an external component on the client e.g., management
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GUI or Wi-Fi framework) is used to manage this functionality.
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Introduction to Wi-Fi Hotspot 2.0
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---------------------------------
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Hotspot 2.0 is the name of the Wi-Fi Alliance specification that is used
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in the Wi-Fi CERTIFIED Passpoint<TM> program. More information about
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this is available in this white paper:
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http://www.wi-fi.org/knowledge-center/white-papers/wi-fi-certified-passpoint%E2%84%A2-new-program-wi-fi-alliance%C2%AE-enable-seamless
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The Hotspot 2.0 specification is also available from WFA:
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https://www.wi-fi.org/knowledge-center/published-specifications
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The core Interworking functionality (network selection, GAS/ANQP) were
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standardized in IEEE Std 802.11u-2011 which is now part of the IEEE Std
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802.11-2012.
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wpa_supplicant network selection
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--------------------------------
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Interworking support added option for configuring credentials that can
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work with multiple networks as an alternative to configuration of
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network blocks (e.g., per-SSID parameters). When requested to perform
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network selection, wpa_supplicant picks the highest priority enabled
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network block or credential. If a credential is picked (based on ANQP
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information from APs), a temporary network block is created
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automatically for the matching network. This temporary network block is
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used similarly to the network blocks that can be configured by the user,
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but it is not stored into the configuration file and is meant to be used
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only for temporary period of time since a new one can be created
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whenever needed based on ANQP information and the credential.
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By default, wpa_supplicant is not using automatic network selection
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unless requested explicitly with the interworking_select command. This
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can be changed with the auto_interworking=1 parameter to perform network
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selection automatically whenever trying to find a network for connection
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and none of the enabled network blocks match with the scan results. This
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case works similarly to "interworking_select auto", i.e., wpa_supplicant
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will internally determine which network or credential is going to be
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used based on configured priorities, scan results, and ANQP information.
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wpa_supplicant configuration
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----------------------------
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Interworking and Hotspot 2.0 functionality are optional components that
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need to be enabled in the wpa_supplicant build configuration
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(.config). This is done by adding following parameters into that file:
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CONFIG_INTERWORKING=y
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CONFIG_HS20=y
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It should be noted that this functionality requires a driver that
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supports GAS/ANQP operations. This uses the same design as P2P, i.e.,
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Action frame processing and building in user space within
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wpa_supplicant. The Linux nl80211 driver interface provides the needed
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functionality for this.
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There are number of run-time configuration parameters (e.g., in
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wpa_supplicant.conf when using the configuration file) that can be used
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to control Hotspot 2.0 operations.
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# Enable Interworking
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interworking=1
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# Enable Hotspot 2.0
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hs20=1
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# Parameters for controlling scanning
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# Homogenous ESS identifier
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# If this is set, scans will be used to request response only from BSSes
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# belonging to the specified Homogeneous ESS. This is used only if interworking
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# is enabled.
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#hessid=00:11:22:33:44:55
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# Access Network Type
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# When Interworking is enabled, scans can be limited to APs that advertise the
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# specified Access Network Type (0..15; with 15 indicating wildcard match).
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# This value controls the Access Network Type value in Probe Request frames.
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#access_network_type=15
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# Automatic network selection behavior
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# 0 = do not automatically go through Interworking network selection
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# (i.e., require explicit interworking_select command for this; default)
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# 1 = perform Interworking network selection if one or more
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# credentials have been configured and scan did not find a
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# matching network block
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#auto_interworking=0
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Credentials can be pre-configured for automatic network selection:
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# credential block
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#
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# Each credential used for automatic network selection is configured as a set
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# of parameters that are compared to the information advertised by the APs when
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# interworking_select and interworking_connect commands are used.
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#
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# credential fields:
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#
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# priority: Priority group
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# By default, all networks and credentials get the same priority group
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# (0). This field can be used to give higher priority for credentials
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# (and similarly in struct wpa_ssid for network blocks) to change the
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# Interworking automatic networking selection behavior. The matching
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# network (based on either an enabled network block or a credential)
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# with the highest priority value will be selected.
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#
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# pcsc: Use PC/SC and SIM/USIM card
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#
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# realm: Home Realm for Interworking
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#
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# username: Username for Interworking network selection
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#
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# password: Password for Interworking network selection
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#
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# ca_cert: CA certificate for Interworking network selection
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#
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# client_cert: File path to client certificate file (PEM/DER)
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# This field is used with Interworking networking selection for a case
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# where client certificate/private key is used for authentication
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# (EAP-TLS). Full path to the file should be used since working
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# directory may change when wpa_supplicant is run in the background.
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#
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# Alternatively, a named configuration blob can be used by setting
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# this to blob://blob_name.
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#
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# private_key: File path to client private key file (PEM/DER/PFX)
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# When PKCS#12/PFX file (.p12/.pfx) is used, client_cert should be
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# commented out. Both the private key and certificate will be read
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# from the PKCS#12 file in this case. Full path to the file should be
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# used since working directory may change when wpa_supplicant is run
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# in the background.
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#
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# Windows certificate store can be used by leaving client_cert out and
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# configuring private_key in one of the following formats:
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#
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# cert://substring_to_match
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#
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# hash://certificate_thumbprint_in_hex
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#
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# For example: private_key="hash://63093aa9c47f56ae88334c7b65a4"
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#
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# Note that when running wpa_supplicant as an application, the user
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# certificate store (My user account) is used, whereas computer store
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# (Computer account) is used when running wpasvc as a service.
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#
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# Alternatively, a named configuration blob can be used by setting
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# this to blob://blob_name.
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#
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# private_key_passwd: Password for private key file
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#
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# imsi: IMSI in <MCC> | <MNC> | '-' | <MSIN> format
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#
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# milenage: Milenage parameters for SIM/USIM simulator in <Ki>:<OPc>:<SQN>
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# format
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#
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# domain: Home service provider FQDN
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# This is used to compare against the Domain Name List to figure out
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# whether the AP is operated by the Home SP.
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#
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# roaming_consortium: Roaming Consortium OI
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# If roaming_consortium_len is non-zero, this field contains the
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# Roaming Consortium OI that can be used to determine which access
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# points support authentication with this credential. This is an
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# alternative to the use of the realm parameter. When using Roaming
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# Consortium to match the network, the EAP parameters need to be
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# pre-configured with the credential since the NAI Realm information
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# may not be available or fetched.
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#
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# eap: Pre-configured EAP method
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# This optional field can be used to specify which EAP method will be
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# used with this credential. If not set, the EAP method is selected
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# automatically based on ANQP information (e.g., NAI Realm).
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#
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# phase1: Pre-configure Phase 1 (outer authentication) parameters
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# This optional field is used with like the 'eap' parameter.
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#
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# phase2: Pre-configure Phase 2 (inner authentication) parameters
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# This optional field is used with like the 'eap' parameter.
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#
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# for example:
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#
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#cred={
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# realm="example.com"
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# username="user@example.com"
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# password="password"
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# ca_cert="/etc/wpa_supplicant/ca.pem"
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# domain="example.com"
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#}
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#
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#cred={
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# imsi="310026-000000000"
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# milenage="90dca4eda45b53cf0f12d7c9c3bc6a89:cb9cccc4b9258e6dca4760379fb82"
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#}
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#
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#cred={
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# realm="example.com"
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# username="user"
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# password="password"
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# ca_cert="/etc/wpa_supplicant/ca.pem"
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# domain="example.com"
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# roaming_consortium=223344
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# eap=TTLS
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# phase2="auth=MSCHAPV2"
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#}
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Control interface
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-----------------
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wpa_supplicant provides a control interface that can be used from
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external programs to manage various operations. The included command
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line tool, wpa_cli, can be used for manual testing with this interface.
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Following wpa_cli interactive mode commands show some examples of manual
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operations related to Hotspot 2.0:
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Remove configured networks and credentials:
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> remove_network all
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OK
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> remove_cred all
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OK
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Add a username/password credential:
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> add_cred
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0
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> set_cred 0 realm "mail.example.com"
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OK
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> set_cred 0 username "username"
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OK
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> set_cred 0 password "password"
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OK
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> set_cred 0 priority 1
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OK
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Add a SIM credential using a simulated SIM/USIM card for testing:
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> add_cred
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1
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> set_cred 1 imsi "23456-0000000000"
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OK
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> set_cred 1 milenage "90dca4eda45b53cf0f12d7c9c3bc6a89:cb9cccc4b9258e6dca4760379fb82581:000000000123"
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OK
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> set_cred 1 priority 1
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OK
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Note: the return value of add_cred is used as the first argument to
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the following set_cred commands.
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Add a WPA2-Enterprise network:
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> add_network
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0
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> set_network 0 key_mgmt WPA-EAP
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OK
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> set_network 0 ssid "enterprise"
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OK
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> set_network 0 eap TTLS
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OK
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> set_network 0 anonymous_identity "anonymous"
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OK
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> set_network 0 identity "user"
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OK
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> set_network 0 password "password"
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OK
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> set_network 0 priority 0
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OK
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> enable_network 0 no-connect
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OK
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Add an open network:
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> add_network
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3
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> set_network 3 key_mgmt NONE
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OK
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> set_network 3 ssid "coffee-shop"
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OK
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> select_network 3
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OK
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Note: the return value of add_network is used as the first argument to
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the following set_network commands.
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The preferred credentials/networks can be indicated with the priority
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parameter (1 is higher priority than 0).
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Interworking network selection can be started with interworking_select
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command. This instructs wpa_supplicant to run a network scan and iterate
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through the discovered APs to request ANQP information from the APs that
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advertise support for Interworking/Hotspot 2.0:
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> interworking_select
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OK
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<3>Starting ANQP fetch for 02:00:00:00:01:00
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<3>RX-ANQP 02:00:00:00:01:00 ANQP Capability list
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<3>RX-ANQP 02:00:00:00:01:00 Roaming Consortium list
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<3>RX-HS20-ANQP 02:00:00:00:01:00 HS Capability List
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<3>ANQP fetch completed
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<3>INTERWORKING-AP 02:00:00:00:01:00 type=unknown
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INTERWORKING-AP event messages indicate the APs that support network
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selection and for which there is a matching
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credential. interworking_connect command can be used to select a network
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to connect with:
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> interworking_connect 02:00:00:00:01:00
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OK
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<3>CTRL-EVENT-SCAN-RESULTS
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<3>SME: Trying to authenticate with 02:00:00:00:01:00 (SSID='Example Network' freq=2412 MHz)
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<3>Trying to associate with 02:00:00:00:01:00 (SSID='Example Network' freq=2412 MHz)
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<3>Associated with 02:00:00:00:01:00
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<3>CTRL-EVENT-EAP-STARTED EAP authentication started
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<3>CTRL-EVENT-EAP-PROPOSED-METHOD vendor=0 method=21
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<3>CTRL-EVENT-EAP-METHOD EAP vendor 0 method 21 (TTLS) selected
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<3>CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
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<3>WPA: Key negotiation completed with 02:00:00:00:01:00 [PTK=CCMP GTK=CCMP]
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<3>CTRL-EVENT-CONNECTED - Connection to 02:00:00:00:01:00 completed (auth) [id=0 id_str=]
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wpa_supplicant creates a temporary network block for the selected
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network based on the configured credential and ANQP information from the
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AP:
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> list_networks
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network id / ssid / bssid / flags
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0 Example Network any [CURRENT]
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> get_network 0 key_mgmt
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WPA-EAP
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> get_network 0 eap
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TTLS
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Alternatively to using an external program to select the network,
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"interworking_select auto" command can be used to request wpa_supplicant
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to select which network to use based on configured priorities:
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> remove_network all
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OK
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<3>CTRL-EVENT-DISCONNECTED bssid=02:00:00:00:01:00 reason=1 locally_generated=1
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> interworking_select auto
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OK
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<3>Starting ANQP fetch for 02:00:00:00:01:00
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<3>RX-ANQP 02:00:00:00:01:00 ANQP Capability list
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<3>RX-ANQP 02:00:00:00:01:00 Roaming Consortium list
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<3>RX-HS20-ANQP 02:00:00:00:01:00 HS Capability List
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<3>ANQP fetch completed
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<3>INTERWORKING-AP 02:00:00:00:01:00 type=unknown
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<3>CTRL-EVENT-SCAN-RESULTS
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<3>SME: Trying to authenticate with 02:00:00:00:01:00 (SSID='Example Network' freq=2412 MHz)
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<3>Trying to associate with 02:00:00:00:01:00 (SSID='Example Network' freq=2412 MHz)
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<3>Associated with 02:00:00:00:01:00
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<3>CTRL-EVENT-EAP-STARTED EAP authentication started
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<3>CTRL-EVENT-EAP-PROPOSED-METHOD vendor=0 method=21
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<3>CTRL-EVENT-EAP-METHOD EAP vendor 0 method 21 (TTLS) selected
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<3>CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
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<3>WPA: Key negotiation completed with 02:00:00:00:01:00 [PTK=CCMP GTK=CCMP]
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<3>CTRL-EVENT-CONNECTED - Connection to 02:00:00:00:01:00 completed (reauth) [id=0 id_str=]
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The connection status can be shown with the status command:
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> status
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bssid=02:00:00:00:01:00
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ssid=Example Network
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id=0
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mode=station
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pairwise_cipher=CCMP <--- link layer security indication
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group_cipher=CCMP
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key_mgmt=WPA2/IEEE 802.1X/EAP
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wpa_state=COMPLETED
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p2p_device_address=02:00:00:00:00:00
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address=02:00:00:00:00:00
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hs20=1 <--- HS 2.0 indication
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Supplicant PAE state=AUTHENTICATED
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suppPortStatus=Authorized
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EAP state=SUCCESS
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selectedMethod=21 (EAP-TTLS)
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EAP TLS cipher=AES-128-SHA
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EAP-TTLSv0 Phase2 method=PAP
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> status
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bssid=02:00:00:00:02:00
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ssid=coffee-shop
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id=3
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mode=station
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pairwise_cipher=NONE
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group_cipher=NONE
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key_mgmt=NONE
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wpa_state=COMPLETED
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p2p_device_address=02:00:00:00:00:00
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address=02:00:00:00:00:00
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Note: The Hotspot 2.0 indication is shown as "hs20=1" in the status
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command output. Link layer security is indicated with the
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pairwise_cipher (CCMP = secure, NONE = no encryption used).
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Also the scan results include the Hotspot 2.0 indication:
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> scan_results
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bssid / frequency / signal level / flags / ssid
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02:00:00:00:01:00 2412 -30 [WPA2-EAP-CCMP][ESS][HS20] Example Network
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ANQP information for the BSS can be fetched using the BSS command:
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> bss 02:00:00:00:01:00
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id=1
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bssid=02:00:00:00:01:00
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freq=2412
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beacon_int=100
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capabilities=0x0411
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qual=0
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noise=-92
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level=-30
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tsf=1345573286517276
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age=105
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ie=000f4578616d706c65204e6574776f726b010882848b960c1218240301012a010432043048606c30140100000fac040100000fac040100000fac0100007f04000000806b091e07010203040506076c027f006f1001531122331020304050010203040506dd05506f9a1000
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flags=[WPA2-EAP-CCMP][ESS][HS20]
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ssid=Example Network
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anqp_roaming_consortium=031122330510203040500601020304050603fedcba
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ANQP queries can also be requested with the anqp_get and hs20_anqp_get
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commands:
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> anqp_get 02:00:00:00:01:00 261
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OK
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<3>RX-ANQP 02:00:00:00:01:00 Roaming Consortium list
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> hs20_anqp_get 02:00:00:00:01:00 2
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OK
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<3>RX-HS20-ANQP 02:00:00:00:01:00 HS Capability List
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In addition, fetch_anqp command can be used to request similar set of
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ANQP queries to be done as is run as part of interworking_select:
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> scan
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OK
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<3>CTRL-EVENT-SCAN-RESULTS
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> fetch_anqp
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OK
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<3>Starting ANQP fetch for 02:00:00:00:01:00
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<3>RX-ANQP 02:00:00:00:01:00 ANQP Capability list
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<3>RX-ANQP 02:00:00:00:01:00 Roaming Consortium list
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<3>RX-HS20-ANQP 02:00:00:00:01:00 HS Capability List
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<3>ANQP fetch completed
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