wpa_supplicant and Hotspot 2.0
==============================
This document describe how the IEEE 802.11u Interworking and Wi-Fi
Hotspot 2.0 (Release 1) implementation in wpa_supplicant can be
configured and how an external component on the client e.g., management
GUI or Wi-Fi framework) is used to manage this functionality.
Introduction to Wi-Fi Hotspot 2.0
---------------------------------
Hotspot 2.0 is the name of the Wi-Fi Alliance specification that is used
in the Wi-Fi CERTIFIED Passpoint<TM> program. More information about
this is available in this white paper:
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
The Hotspot 2.0 specification is also available from WFA:
https://www.wi-fi.org/knowledge-center/published-specifications
The core Interworking functionality (network selection, GAS/ANQP) were
standardized in IEEE Std 802.11u-2011 which is now part of the IEEE Std
802.11-2012.
wpa_supplicant network selection
--------------------------------
Interworking support added option for configuring credentials that can
work with multiple networks as an alternative to configuration of
network blocks (e.g., per-SSID parameters). When requested to perform
network selection, wpa_supplicant picks the highest priority enabled
network block or credential. If a credential is picked (based on ANQP
information from APs), a temporary network block is created
automatically for the matching network. This temporary network block is
used similarly to the network blocks that can be configured by the user,
but it is not stored into the configuration file and is meant to be used
only for temporary period of time since a new one can be created
whenever needed based on ANQP information and the credential.
By default, wpa_supplicant is not using automatic network selection
unless requested explicitly with the interworking_select command. This
can be changed with the auto_interworking=1 parameter to perform network
selection automatically whenever trying to find a network for connection
and none of the enabled network blocks match with the scan results. This
case works similarly to "interworking_select auto", i.e., wpa_supplicant
will internally determine which network or credential is going to be
used based on configured priorities, scan results, and ANQP information.
wpa_supplicant configuration
----------------------------
Interworking and Hotspot 2.0 functionality are optional components that
need to be enabled in the wpa_supplicant build configuration
(.config). This is done by adding following parameters into that file:
CONFIG_INTERWORKING=y
CONFIG_HS20=y
It should be noted that this functionality requires a driver that
supports GAS/ANQP operations. This uses the same design as P2P, i.e.,
Action frame processing and building in user space within
wpa_supplicant. The Linux nl80211 driver interface provides the needed
functionality for this.
There are number of run-time configuration parameters (e.g., in
wpa_supplicant.conf when using the configuration file) that can be used
to control Hotspot 2.0 operations.
# Enable Interworking
interworking=1
# Enable Hotspot 2.0
hs20=1
# Parameters for controlling scanning
# Homogenous ESS identifier
# If this is set, scans will be used to request response only from BSSes
# belonging to the specified Homogeneous ESS. This is used only if interworking
# is enabled.
#hessid=00:11:22:33:44:55
# Access Network Type
# When Interworking is enabled, scans can be limited to APs that advertise the
# specified Access Network Type (0..15; with 15 indicating wildcard match).
# This value controls the Access Network Type value in Probe Request frames.
#access_network_type=15
# Automatic network selection behavior
# 0 = do not automatically go through Interworking network selection
# (i.e., require explicit interworking_select command for this; default)
# 1 = perform Interworking network selection if one or more
# credentials have been configured and scan did not find a
# matching network block
#auto_interworking=0
Credentials can be pre-configured for automatic network selection:
# credential block
#
# Each credential used for automatic network selection is configured as a set
# of parameters that are compared to the information advertised by the APs when
# interworking_select and interworking_connect commands are used.
#
# credential fields:
#
# temporary: Whether this credential is temporary and not to be saved
#
# priority: Priority group
# By default, all networks and credentials get the same priority group
# (0). This field can be used to give higher priority for credentials
# (and similarly in struct wpa_ssid for network blocks) to change the
# Interworking automatic networking selection behavior. The matching
# network (based on either an enabled network block or a credential)
# with the highest priority value will be selected.
#
# pcsc: Use PC/SC and SIM/USIM card
#
# realm: Home Realm for Interworking
#
# username: Username for Interworking network selection
#
# password: Password for Interworking network selection
#
# ca_cert: CA certificate for Interworking network selection
#
# client_cert: File path to client certificate file (PEM/DER)
# This field is used with Interworking networking selection for a case
# where client certificate/private key is used for authentication
# (EAP-TLS). Full path to the file should be used since working
# directory may change when wpa_supplicant is run in the background.
#
# Alternatively, a named configuration blob can be used by setting
# this to blob://blob_name.
#
# private_key: File path to client private key file (PEM/DER/PFX)
# When PKCS#12/PFX file (.p12/.pfx) is used, client_cert should be
# commented out. Both the private key and certificate will be read
# from the PKCS#12 file in this case. Full path to the file should be
# used since working directory may change when wpa_supplicant is run
# in the background.
#
# Windows certificate store can be used by leaving client_cert out and
# configuring private_key in one of the following formats:
#
# cert://substring_to_match
#
# hash://certificate_thumbprint_in_hex
#
# For example: private_key="hash://63093aa9c47f56ae88334c7b65a4"
#
# Note that when running wpa_supplicant as an application, the user
# certificate store (My user account) is used, whereas computer store
# (Computer account) is used when running wpasvc as a service.
#
# Alternatively, a named configuration blob can be used by setting
# this to blob://blob_name.
#
# private_key_passwd: Password for private key file
#
# imsi: IMSI in <MCC> | <MNC> | '-' | <MSIN> format
#
# milenage: Milenage parameters for SIM/USIM simulator in <Ki>:<OPc>:<SQN>
# format
#
# domain_suffix_match: Constraint for server domain name
# If set, this FQDN is used as a suffix match requirement for the AAA
# server certificate in SubjectAltName dNSName element(s). If a
# matching dNSName is found, this constraint is met. If no dNSName
# values are present, this constraint is matched against SubjectName CN
# using same suffix match comparison. Suffix match here means that the
# host/domain name is compared one label at a time starting from the
# top-level domain and all the labels in @domain_suffix_match shall be
# included in the certificate. The certificate may include additional
# sub-level labels in addition to the required labels.
#
# For example, domain_suffix_match=example.com would match
# test.example.com but would not match test-example.com.
#
# domain: Home service provider FQDN(s)
# This is used to compare against the Domain Name List to figure out
# whether the AP is operated by the Home SP. Multiple domain entries can
# be used to configure alternative FQDNs that will be considered home
# networks.
#
# roaming_consortium: Roaming Consortium OI
# If roaming_consortium_len is non-zero, this field contains the
# Roaming Consortium OI that can be used to determine which access
# points support authentication with this credential. This is an
# alternative to the use of the realm parameter. When using Roaming
# Consortium to match the network, the EAP parameters need to be
# pre-configured with the credential since the NAI Realm information
# may not be available or fetched.
#
# eap: Pre-configured EAP method
# This optional field can be used to specify which EAP method will be
# used with this credential. If not set, the EAP method is selected
# automatically based on ANQP information (e.g., NAI Realm).
#
# phase1: Pre-configure Phase 1 (outer authentication) parameters
# This optional field is used with like the 'eap' parameter.
#
# phase2: Pre-configure Phase 2 (inner authentication) parameters
# This optional field is used with like the 'eap' parameter.
#
# excluded_ssid: Excluded SSID
# This optional field can be used to excluded specific SSID(s) from
# matching with the network. Multiple entries can be used to specify more
# than one SSID.
#
# roaming_partner: Roaming partner information
# This optional field can be used to configure preferences between roaming
# partners. The field is a string in following format:
# <FQDN>,<0/1 exact match>,<priority>,<* or country code>
# (non-exact match means any subdomain matches the entry; priority is in
# 0..255 range with 0 being the highest priority)
#
# update_identifier: PPS MO ID
# (Hotspot 2.0 PerProviderSubscription/UpdateIdentifier)
#
# provisioning_sp: FQDN of the SP that provisioned the credential
# This optional field can be used to keep track of the SP that provisioned
# the credential to find the PPS MO (./Wi-Fi/<provisioning_sp>).
#
# sp_priority: Credential priority within a provisioning SP
# This is the priority of the credential among all credentials
# provisioned by the same SP (i.e., for entries that have identical
# provisioning_sp value). The range of this priority is 0-255 with 0
# being the highest and 255 the lower priority.
#
# Minimum backhaul threshold (PPS/<X+>/Policy/MinBackhauldThreshold/*)
# These fields can be used to specify minimum download/upload backhaul
# bandwidth that is preferred for the credential. This constraint is
# ignored if the AP does not advertise WAN Metrics information or if the
# limit would prevent any connection. Values are in kilobits per second.
# min_dl_bandwidth_home
# min_ul_bandwidth_home
# min_dl_bandwidth_roaming
# min_ul_bandwidth_roaming
#
# max_bss_load: Maximum BSS Load Channel Utilization (1..255)
# (PPS/<X+>/Policy/MaximumBSSLoadValue)
# This value is used as the maximum channel utilization for network
# selection purposes for home networks. If the AP does not advertise
# BSS Load or if the limit would prevent any connection, this constraint
# will be ignored.
#
# req_conn_capab: Required connection capability
# (PPS/<X+>/Policy/RequiredProtoPortTuple)
# This value is used to configure set of required protocol/port pairs that
# a roaming network shall support (include explicitly in Connection
# Capability ANQP element). This constraint is ignored if the AP does not
# advertise Connection Capability or if this constraint would prevent any
# network connection. This policy is not used in home networks.
# Format: <protocol>[:<comma-separated list of ports]
# Multiple entries can be used to list multiple requirements.
# For example, number of common TCP protocols:
# req_conn_capab=6:22,80,443
# For example, IPSec/IKE:
# req_conn_capab=17:500
# req_conn_capab=50
#
# ocsp: Whether to use/require OCSP to check server certificate
# 0 = do not use OCSP stapling (TLS certificate status extension)
# 1 = try to use OCSP stapling, but not require response
# 2 = require valid OCSP stapling response
#
# sim_num: Identifier for which SIM to use in multi-SIM devices
#
# for example:
#
#cred={
# realm="example.com"
# username="user@example.com"
# password="password"
# ca_cert="/etc/wpa_supplicant/ca.pem"
# domain="example.com"
# domain_suffix_match="example.com"
#}
#
#cred={
# imsi="310026-000000000"
# milenage="90dca4eda45b53cf0f12d7c9c3bc6a89:cb9cccc4b9258e6dca4760379fb82"
#}
#
#cred={
# realm="example.com"
# username="user"
# password="password"
# ca_cert="/etc/wpa_supplicant/ca.pem"
# domain="example.com"
# roaming_consortium=223344
# eap=TTLS
# phase2="auth=MSCHAPV2"
#}
Control interface
-----------------
wpa_supplicant provides a control interface that can be used from
external programs to manage various operations. The included command
line tool, wpa_cli, can be used for manual testing with this interface.
Following wpa_cli interactive mode commands show some examples of manual
operations related to Hotspot 2.0:
Remove configured networks and credentials:
> remove_network all
OK
> remove_cred all
OK
Add a username/password credential:
> add_cred
0
> set_cred 0 realm "mail.example.com"
OK
> set_cred 0 username "username"
OK
> set_cred 0 password "password"
OK
> set_cred 0 priority 1
OK
> set_cred 0 temporary 1
OK
Add a SIM credential using a simulated SIM/USIM card for testing:
> add_cred
1
> set_cred 1 imsi "23456-0000000000"
OK
> set_cred 1 milenage "90dca4eda45b53cf0f12d7c9c3bc6a89:cb9cccc4b9258e6dca4760379fb82581:000000000123"
OK
> set_cred 1 priority 1
OK
Note: the return value of add_cred is used as the first argument to
the following set_cred commands.
Add a SIM credential using a external SIM/USIM processing:
> set external_sim 1
OK
> add_cred
1
> set_cred 1 imsi "23456-0000000000"
OK
> set_cred 1 eap SIM
OK
Add a WPA2-Enterprise network:
> add_network
0
> set_network 0 key_mgmt WPA-EAP
OK
> set_network 0 ssid "enterprise"
OK
> set_network 0 eap TTLS
OK
> set_network 0 anonymous_identity "anonymous"
OK
> set_network 0 identity "user"
OK
> set_network 0 password "password"
OK
> set_network 0 priority 0
OK
> enable_network 0 no-connect
OK
Add an open network:
> add_network
3
> set_network 3 key_mgmt NONE
OK
> set_network 3 ssid "coffee-shop"
OK
> select_network 3
OK
Note: the return value of add_network is used as the first argument to
the following set_network commands.
The preferred credentials/networks can be indicated with the priority
parameter (1 is higher priority than 0).
Interworking network selection can be started with interworking_select
command. This instructs wpa_supplicant to run a network scan and iterate
through the discovered APs to request ANQP information from the APs that
advertise support for Interworking/Hotspot 2.0:
> interworking_select
OK
<3>Starting ANQP fetch for 02:00:00:00:01:00
<3>RX-ANQP 02:00:00:00:01:00 ANQP Capability list
<3>RX-ANQP 02:00:00:00:01:00 Roaming Consortium list
<3>RX-HS20-ANQP 02:00:00:00:01:00 HS Capability List
<3>ANQP fetch completed
<3>INTERWORKING-AP 02:00:00:00:01:00 type=unknown
INTERWORKING-AP event messages indicate the APs that support network
selection and for which there is a matching
credential. interworking_connect command can be used to select a network
to connect with:
> interworking_connect 02:00:00:00:01:00
OK
<3>CTRL-EVENT-SCAN-RESULTS
<3>SME: Trying to authenticate with 02:00:00:00:01:00 (SSID='Example Network' freq=2412 MHz)
<3>Trying to associate with 02:00:00:00:01:00 (SSID='Example Network' freq=2412 MHz)
<3>Associated with 02:00:00:00:01:00
<3>CTRL-EVENT-EAP-STARTED EAP authentication started
<3>CTRL-EVENT-EAP-PROPOSED-METHOD vendor=0 method=21
<3>CTRL-EVENT-EAP-METHOD EAP vendor 0 method 21 (TTLS) selected
<3>CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
<3>WPA: Key negotiation completed with 02:00:00:00:01:00 [PTK=CCMP GTK=CCMP]
<3>CTRL-EVENT-CONNECTED - Connection to 02:00:00:00:01:00 completed (auth) [id=0 id_str=]
wpa_supplicant creates a temporary network block for the selected
network based on the configured credential and ANQP information from the
AP:
> list_networks
network id / ssid / bssid / flags
0 Example Network any [CURRENT]
> get_network 0 key_mgmt
WPA-EAP
> get_network 0 eap
TTLS
Alternatively to using an external program to select the network,
"interworking_select auto" command can be used to request wpa_supplicant
to select which network to use based on configured priorities:
> remove_network all
OK
<3>CTRL-EVENT-DISCONNECTED bssid=02:00:00:00:01:00 reason=1 locally_generated=1
> interworking_select auto
OK
<3>Starting ANQP fetch for 02:00:00:00:01:00
<3>RX-ANQP 02:00:00:00:01:00 ANQP Capability list
<3>RX-ANQP 02:00:00:00:01:00 Roaming Consortium list
<3>RX-HS20-ANQP 02:00:00:00:01:00 HS Capability List
<3>ANQP fetch completed
<3>INTERWORKING-AP 02:00:00:00:01:00 type=unknown
<3>CTRL-EVENT-SCAN-RESULTS
<3>SME: Trying to authenticate with 02:00:00:00:01:00 (SSID='Example Network' freq=2412 MHz)
<3>Trying to associate with 02:00:00:00:01:00 (SSID='Example Network' freq=2412 MHz)
<3>Associated with 02:00:00:00:01:00
<3>CTRL-EVENT-EAP-STARTED EAP authentication started
<3>CTRL-EVENT-EAP-PROPOSED-METHOD vendor=0 method=21
<3>CTRL-EVENT-EAP-METHOD EAP vendor 0 method 21 (TTLS) selected
<3>CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
<3>WPA: Key negotiation completed with 02:00:00:00:01:00 [PTK=CCMP GTK=CCMP]
<3>CTRL-EVENT-CONNECTED - Connection to 02:00:00:00:01:00 completed (reauth) [id=0 id_str=]
The connection status can be shown with the status command:
> status
bssid=02:00:00:00:01:00
ssid=Example Network
id=0
mode=station
pairwise_cipher=CCMP <--- link layer security indication
group_cipher=CCMP
key_mgmt=WPA2/IEEE 802.1X/EAP
wpa_state=COMPLETED
p2p_device_address=02:00:00:00:00:00
address=02:00:00:00:00:00
hs20=1 <--- HS 2.0 indication
Supplicant PAE state=AUTHENTICATED
suppPortStatus=Authorized
EAP state=SUCCESS
selectedMethod=21 (EAP-TTLS)
EAP TLS cipher=AES-128-SHA
EAP-TTLSv0 Phase2 method=PAP
> status
bssid=02:00:00:00:02:00
ssid=coffee-shop
id=3
mode=station
pairwise_cipher=NONE
group_cipher=NONE
key_mgmt=NONE
wpa_state=COMPLETED
p2p_device_address=02:00:00:00:00:00
address=02:00:00:00:00:00
Note: The Hotspot 2.0 indication is shown as "hs20=1" in the status
command output. Link layer security is indicated with the
pairwise_cipher (CCMP = secure, NONE = no encryption used).
Also the scan results include the Hotspot 2.0 indication:
> scan_results
bssid / frequency / signal level / flags / ssid
02:00:00:00:01:00 2412 -30 [WPA2-EAP-CCMP][ESS][HS20] Example Network
ANQP information for the BSS can be fetched using the BSS command:
> bss 02:00:00:00:01:00
id=1
bssid=02:00:00:00:01:00
freq=2412
beacon_int=100
capabilities=0x0411
qual=0
noise=-92
level=-30
tsf=1345573286517276
age=105
ie=000f4578616d706c65204e6574776f726b010882848b960c1218240301012a010432043048606c30140100000fac040100000fac040100000fac0100007f04000000806b091e07010203040506076c027f006f1001531122331020304050010203040506dd05506f9a1000
flags=[WPA2-EAP-CCMP][ESS][HS20]
ssid=Example Network
anqp_roaming_consortium=031122330510203040500601020304050603fedcba
ANQP queries can also be requested with the anqp_get and hs20_anqp_get
commands:
> anqp_get 02:00:00:00:01:00 261
OK
<3>RX-ANQP 02:00:00:00:01:00 Roaming Consortium list
> hs20_anqp_get 02:00:00:00:01:00 2
OK
<3>RX-HS20-ANQP 02:00:00:00:01:00 HS Capability List
In addition, fetch_anqp command can be used to request similar set of
ANQP queries to be done as is run as part of interworking_select:
> scan
OK
<3>CTRL-EVENT-SCAN-RESULTS
> fetch_anqp
OK
<3>Starting ANQP fetch for 02:00:00:00:01:00
<3>RX-ANQP 02:00:00:00:01:00 ANQP Capability list
<3>RX-ANQP 02:00:00:00:01:00 Roaming Consortium list
<3>RX-HS20-ANQP 02:00:00:00:01:00 HS Capability List
<3>ANQP fetch completed
Hotspot 2.0 Rel 2 online signup and OSEN
----------------------------------------
Following parameters can be used to create a network profile for
link-layer protected Hotspot 2.0 online signup connection with
OSEN. Note that ssid and identify (NAI) values need to be set based on
the information for the selected provider in the OSU Providers list
ANQP-element.
network={
ssid="HS 2.0 OSU"
proto=OSEN
key_mgmt=OSEN
pairwise=CCMP
group=GTK_NOT_USED
eap=WFA-UNAUTH-TLS
identity="anonymous@example.com"
ca_cert="osu-ca.pem"
ocsp=2
}
Hotspot 2.0 connection with external network selection
------------------------------------------------------
When an component controlling wpa_supplicant takes care of Interworking
network selection, following configuration and network profile
parameters can be used to configure a temporary network profile for a
Hotspot 2.0 connection (e.g., with SET, ADD_NETWORK, SET_NETWORK, and
SELECT_NETWORK control interface commands):
interworking=1
hs20=1
auto_interworking=0
network={
ssid="test-hs20"
proto=RSN
key_mgmt=WPA-EAP
pairwise=CCMP
anonymous_identity="anonymous@example.com"
identity="hs20-test@example.com"
password="password"
ca_cert="ca.pem"
eap=TTLS
phase2="auth=MSCHAPV2"
update_identifier=54321
#ocsp=2
}
These parameters are set based on the PPS MO credential and/or NAI Realm
list ANQP-element:
anonymous_identity: Credential/UsernamePassword/Username with username part
replaced with "anonymous"
identity: Credential/UsernamePassword/Username
password: Credential/UsernamePassword/Password
update_identifier: PPS/UpdateIdentifier
ca_cert: from the downloaded trust root based on PPS information
eap: Credential/UsernamePassword/EAPMethod or NAI Realm list
phase2: Credential/UsernamePassword/EAPMethod or NAI Realm list
ocsp: Credential/CheckAAAServerCertStatus