Disconnect hostapd from building in base
[dragonfly.git] / contrib / hostapd / hostapd / README
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1hostapd - user space IEEE 802.11 AP and IEEE 802.1X/WPA/WPA2/EAP
2 Authenticator and RADIUS authentication server
3================================================================
4
4781064b 5Copyright (c) 2002-2014, Jouni Malinen <j@w1.fi> and contributors
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6All Rights Reserved.
7
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8This program is licensed under the BSD license (the one with
9advertisement clause removed).
10
11If you are submitting changes to the project, please see CONTRIBUTIONS
12file for more instructions.
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13
14
15
16License
17-------
18
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19This software may be distributed, used, and modified under the terms of
20BSD license:
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21
22Redistribution and use in source and binary forms, with or without
23modification, are permitted provided that the following conditions are
24met:
25
261. Redistributions of source code must retain the above copyright
27 notice, this list of conditions and the following disclaimer.
28
292. Redistributions in binary form must reproduce the above copyright
30 notice, this list of conditions and the following disclaimer in the
31 documentation and/or other materials provided with the distribution.
32
333. Neither the name(s) of the above-listed copyright holder(s) nor the
34 names of its contributors may be used to endorse or promote products
35 derived from this software without specific prior written permission.
36
37THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
38"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
39LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
40A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
41OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
44DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
45THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
46(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
47OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
48
49
50
51Introduction
52============
53
54Originally, hostapd was an optional user space component for Host AP
55driver. It adds more features to the basic IEEE 802.11 management
56included in the kernel driver: using external RADIUS authentication
57server for MAC address based access control, IEEE 802.1X Authenticator
58and dynamic WEP keying, RADIUS accounting, WPA/WPA2 (IEEE 802.11i/RSN)
59Authenticator and dynamic TKIP/CCMP keying.
60
61The current version includes support for other drivers, an integrated
62EAP server (i.e., allow full authentication without requiring
63an external RADIUS authentication server), and RADIUS authentication
64server for EAP authentication.
65
66
67Requirements
68------------
69
70Current hardware/software requirements:
71- drivers:
72 Host AP driver for Prism2/2.5/3.
73 (http://hostap.epitest.fi/)
74 Please note that station firmware version needs to be 1.7.0 or newer
75 to work in WPA mode.
76
77 madwifi driver for cards based on Atheros chip set (ar521x)
78 (http://sourceforge.net/projects/madwifi/)
79 Please note that you will need to add the correct path for
80 madwifi driver root directory in .config (see defconfig file for
81 an example: CFLAGS += -I<path>)
82
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83 mac80211-based drivers that support AP mode (with driver=nl80211).
84 This includes drivers for Atheros (ath9k) and Broadcom (b43)
85 chipsets.
86
87 Any wired Ethernet driver for wired IEEE 802.1X authentication
88 (experimental code)
89
90 FreeBSD -current (with some kernel mods that have not yet been
91 committed when hostapd v0.3.0 was released)
92 BSD net80211 layer (e.g., Atheros driver)
93
94
95Build configuration
96-------------------
97
98In order to be able to build hostapd, you will need to create a build
99time configuration file, .config that selects which optional
100components are included. See defconfig file for example configuration
101and list of available options.
102
103
104
105IEEE 802.1X
106===========
107
108IEEE Std 802.1X-2001 is a standard for port-based network access
109control. In case of IEEE 802.11 networks, a "virtual port" is used
110between each associated station and the AP. IEEE 802.11 specifies
111minimal authentication mechanism for stations, whereas IEEE 802.1X
112introduces a extensible mechanism for authenticating and authorizing
113users.
114
115IEEE 802.1X uses elements called Supplicant, Authenticator, Port
116Access Entity, and Authentication Server. Supplicant is a component in
117a station and it performs the authentication with the Authentication
118Server. An access point includes an Authenticator that relays the packets
119between a Supplicant and an Authentication Server. In addition, it has a
120Port Access Entity (PAE) with Authenticator functionality for
121controlling the virtual port authorization, i.e., whether to accept
122packets from or to the station.
123
124IEEE 802.1X uses Extensible Authentication Protocol (EAP). The frames
125between a Supplicant and an Authenticator are sent using EAP over LAN
126(EAPOL) and the Authenticator relays these frames to the Authentication
127Server (and similarly, relays the messages from the Authentication
128Server to the Supplicant). The Authentication Server can be colocated with the
129Authenticator, in which case there is no need for additional protocol
130for EAP frame transmission. However, a more common configuration is to
131use an external Authentication Server and encapsulate EAP frame in the
132frames used by that server. RADIUS is suitable for this, but IEEE
133802.1X would also allow other mechanisms.
134
135Host AP driver includes PAE functionality in the kernel driver. It
136is a relatively simple mechanism for denying normal frames going to
137or coming from an unauthorized port. PAE allows IEEE 802.1X related
138frames to be passed between the Supplicant and the Authenticator even
139on an unauthorized port.
140
141User space daemon, hostapd, includes Authenticator functionality. It
142receives 802.1X (EAPOL) frames from the Supplicant using the wlan#ap
143device that is also used with IEEE 802.11 management frames. The
144frames to the Supplicant are sent using the same device.
145
146The normal configuration of the Authenticator would use an external
147Authentication Server. hostapd supports RADIUS encapsulation of EAP
148packets, so the Authentication Server should be a RADIUS server, like
149FreeRADIUS (http://www.freeradius.org/). The Authenticator in hostapd
150relays the frames between the Supplicant and the Authentication
151Server. It also controls the PAE functionality in the kernel driver by
152controlling virtual port authorization, i.e., station-AP
153connection, based on the IEEE 802.1X state.
154
155When a station would like to use the services of an access point, it
156will first perform IEEE 802.11 authentication. This is normally done
157with open systems authentication, so there is no security. After
158this, IEEE 802.11 association is performed. If IEEE 802.1X is
159configured to be used, the virtual port for the station is set in
160Unauthorized state and only IEEE 802.1X frames are accepted at this
161point. The Authenticator will then ask the Supplicant to authenticate
162with the Authentication Server. After this is completed successfully,
163the virtual port is set to Authorized state and frames from and to the
164station are accepted.
165
166Host AP configuration for IEEE 802.1X
167-------------------------------------
168
169The user space daemon has its own configuration file that can be used to
170define AP options. Distribution package contains an example
171configuration file (hostapd/hostapd.conf) that can be used as a basis
172for configuration. It includes examples of all supported configuration
173options and short description of each option. hostapd should be started
174with full path to the configuration file as the command line argument,
175e.g., './hostapd /etc/hostapd.conf'. If you have more that one wireless
176LAN card, you can use one hostapd process for multiple interfaces by
177giving a list of configuration files (one per interface) in the command
178line.
179
180hostapd includes a minimal co-located IEEE 802.1X server which can be
181used to test IEEE 802.1X authentication. However, it should not be
182used in normal use since it does not provide any security. This can be
183configured by setting ieee8021x and minimal_eap options in the
184configuration file.
185
186An external Authentication Server (RADIUS) is configured with
187auth_server_{addr,port,shared_secret} options. In addition,
188ieee8021x and own_ip_addr must be set for this mode. With such
189configuration, the co-located Authentication Server is not used and EAP
190frames will be relayed using EAPOL between the Supplicant and the
191Authenticator and RADIUS encapsulation between the Authenticator and
192the Authentication Server. Other than this, the functionality is similar
193to the case with the co-located Authentication Server.
194
195Authentication Server and Supplicant
196------------------------------------
197
198Any RADIUS server supporting EAP should be usable as an IEEE 802.1X
199Authentication Server with hostapd Authenticator. FreeRADIUS
200(http://www.freeradius.org/) has been successfully tested with hostapd
201Authenticator and both Xsupplicant (http://www.open1x.org) and Windows
202XP Supplicants. EAP/TLS was used with Xsupplicant and
203EAP/MD5-Challenge with Windows XP.
204
205http://www.missl.cs.umd.edu/wireless/eaptls/ has useful information
206about using EAP/TLS with FreeRADIUS and Xsupplicant (just replace
207Cisco access point with Host AP driver, hostapd daemon, and a Prism2
208card ;-). http://www.freeradius.org/doc/EAP-MD5.html has information
209about using EAP/MD5 with FreeRADIUS, including instructions for WinXP
210configuration. http://www.denobula.com/EAPTLS.pdf has a HOWTO on
211EAP/TLS use with WinXP Supplicant.
212
213Automatic WEP key configuration
214-------------------------------
215
216EAP/TLS generates a session key that can be used to send WEP keys from
217an AP to authenticated stations. The Authenticator in hostapd can be
218configured to automatically select a random default/broadcast key
219(shared by all authenticated stations) with wep_key_len_broadcast
220option (5 for 40-bit WEP or 13 for 104-bit WEP). In addition,
221wep_key_len_unicast option can be used to configure individual unicast
222keys for stations. This requires support for individual keys in the
223station driver.
224
225WEP keys can be automatically updated by configuring rekeying. This
226will improve security of the network since same WEP key will only be
227used for a limited period of time. wep_rekey_period option sets the
228interval for rekeying in seconds.
229
230
231WPA/WPA2
232========
233
234Features
235--------
236
237Supported WPA/IEEE 802.11i features:
238- WPA-PSK ("WPA-Personal")
239- WPA with EAP (e.g., with RADIUS authentication server) ("WPA-Enterprise")
240- key management for CCMP, TKIP, WEP104, WEP40
241- RSN/WPA2 (IEEE 802.11i), including PMKSA caching and pre-authentication
242
243WPA
244---
245
246The original security mechanism of IEEE 802.11 standard was not
247designed to be strong and has proved to be insufficient for most
248networks that require some kind of security. Task group I (Security)
249of IEEE 802.11 working group (http://www.ieee802.org/11/) has worked
250to address the flaws of the base standard and has in practice
251completed its work in May 2004. The IEEE 802.11i amendment to the IEEE
252802.11 standard was approved in June 2004 and this amendment is likely
253to be published in July 2004.
254
255Wi-Fi Alliance (http://www.wi-fi.org/) used a draft version of the
256IEEE 802.11i work (draft 3.0) to define a subset of the security
257enhancements that can be implemented with existing wlan hardware. This
258is called Wi-Fi Protected Access<TM> (WPA). This has now become a
259mandatory component of interoperability testing and certification done
260by Wi-Fi Alliance. Wi-Fi provides information about WPA at its web
261site (http://www.wi-fi.org/OpenSection/protected_access.asp).
262
263IEEE 802.11 standard defined wired equivalent privacy (WEP) algorithm
264for protecting wireless networks. WEP uses RC4 with 40-bit keys,
26524-bit initialization vector (IV), and CRC32 to protect against packet
266forgery. All these choices have proven to be insufficient: key space is
267too small against current attacks, RC4 key scheduling is insufficient
268(beginning of the pseudorandom stream should be skipped), IV space is
269too small and IV reuse makes attacks easier, there is no replay
270protection, and non-keyed authentication does not protect against bit
271flipping packet data.
272
273WPA is an intermediate solution for the security issues. It uses
274Temporal Key Integrity Protocol (TKIP) to replace WEP. TKIP is a
275compromise on strong security and possibility to use existing
276hardware. It still uses RC4 for the encryption like WEP, but with
277per-packet RC4 keys. In addition, it implements replay protection,
278keyed packet authentication mechanism (Michael MIC).
279
280Keys can be managed using two different mechanisms. WPA can either use
281an external authentication server (e.g., RADIUS) and EAP just like
282IEEE 802.1X is using or pre-shared keys without need for additional
283servers. Wi-Fi calls these "WPA-Enterprise" and "WPA-Personal",
284respectively. Both mechanisms will generate a master session key for
285the Authenticator (AP) and Supplicant (client station).
286
287WPA implements a new key handshake (4-Way Handshake and Group Key
288Handshake) for generating and exchanging data encryption keys between
289the Authenticator and Supplicant. This handshake is also used to
290verify that both Authenticator and Supplicant know the master session
291key. These handshakes are identical regardless of the selected key
292management mechanism (only the method for generating master session
293key changes).
294
295
296IEEE 802.11i / WPA2
297-------------------
298
299The design for parts of IEEE 802.11i that were not included in WPA has
300finished (May 2004) and this amendment to IEEE 802.11 was approved in
301June 2004. Wi-Fi Alliance is using the final IEEE 802.11i as a new
302version of WPA called WPA2. This includes, e.g., support for more
303robust encryption algorithm (CCMP: AES in Counter mode with CBC-MAC)
304to replace TKIP and optimizations for handoff (reduced number of
305messages in initial key handshake, pre-authentication, and PMKSA caching).
306
307Some wireless LAN vendors are already providing support for CCMP in
308their WPA products. There is no "official" interoperability
309certification for CCMP and/or mixed modes using both TKIP and CCMP, so
310some interoperability issues can be expected even though many
311combinations seem to be working with equipment from different vendors.
312Testing for WPA2 is likely to start during the second half of 2004.
313
314hostapd configuration for WPA/WPA2
315----------------------------------
316
317TODO
318
319# Enable WPA. Setting this variable configures the AP to require WPA (either
320# WPA-PSK or WPA-RADIUS/EAP based on other configuration). For WPA-PSK, either
321# wpa_psk or wpa_passphrase must be set and wpa_key_mgmt must include WPA-PSK.
322# For WPA-RADIUS/EAP, ieee8021x must be set (but without dynamic WEP keys),
323# RADIUS authentication server must be configured, and WPA-EAP must be included
324# in wpa_key_mgmt.
325# This field is a bit field that can be used to enable WPA (IEEE 802.11i/D3.0)
326# and/or WPA2 (full IEEE 802.11i/RSN):
327# bit0 = WPA
328# bit1 = IEEE 802.11i/RSN (WPA2)
329#wpa=1
330
331# WPA pre-shared keys for WPA-PSK. This can be either entered as a 256-bit
332# secret in hex format (64 hex digits), wpa_psk, or as an ASCII passphrase
333# (8..63 characters) that will be converted to PSK. This conversion uses SSID
334# so the PSK changes when ASCII passphrase is used and the SSID is changed.
335#wpa_psk=0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef
336#wpa_passphrase=secret passphrase
337
338# Set of accepted key management algorithms (WPA-PSK, WPA-EAP, or both). The
339# entries are separated with a space.
340#wpa_key_mgmt=WPA-PSK WPA-EAP
341
342# Set of accepted cipher suites (encryption algorithms) for pairwise keys
343# (unicast packets). This is a space separated list of algorithms:
344# CCMP = AES in Counter mode with CBC-MAC [RFC 3610, IEEE 802.11i]
345# TKIP = Temporal Key Integrity Protocol [IEEE 802.11i]
346# Group cipher suite (encryption algorithm for broadcast and multicast frames)
347# is automatically selected based on this configuration. If only CCMP is
348# allowed as the pairwise cipher, group cipher will also be CCMP. Otherwise,
349# TKIP will be used as the group cipher.
350#wpa_pairwise=TKIP CCMP
351
352# Time interval for rekeying GTK (broadcast/multicast encryption keys) in
353# seconds.
354#wpa_group_rekey=600
355
356# Time interval for rekeying GMK (master key used internally to generate GTKs
357# (in seconds).
358#wpa_gmk_rekey=86400
359
360# Enable IEEE 802.11i/RSN/WPA2 pre-authentication. This is used to speed up
361# roaming be pre-authenticating IEEE 802.1X/EAP part of the full RSN
362# authentication and key handshake before actually associating with a new AP.
363#rsn_preauth=1
364#
365# Space separated list of interfaces from which pre-authentication frames are
366# accepted (e.g., 'eth0' or 'eth0 wlan0wds0'. This list should include all
367# interface that are used for connections to other APs. This could include
368# wired interfaces and WDS links. The normal wireless data interface towards
369# associated stations (e.g., wlan0) should not be added, since
370# pre-authentication is only used with APs other than the currently associated
371# one.
372#rsn_preauth_interfaces=eth0