1 hostapd - user space IEEE 802.11 AP and IEEE 802.1X/WPA/WPA2/EAP 2 Authenticator and RADIUS authentication server 3 ================================================================ 4 5 Copyright (c) 2002-2012, Jouni Malinen <j (a] w1.fi> and contributors 6 All Rights Reserved. 7 8 This program is licensed under the BSD license (the one with 9 advertisement clause removed). 10 11 If you are submitting changes to the project, please see CONTRIBUTIONS 12 file for more instructions. 13 14 15 16 License 17 ------- 18 19 This software may be distributed, used, and modified under the terms of 20 BSD license: 21 22 Redistribution and use in source and binary forms, with or without 23 modification, are permitted provided that the following conditions are 24 met: 25 26 1. Redistributions of source code must retain the above copyright 27 notice, this list of conditions and the following disclaimer. 28 29 2. 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 33 3. 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 37 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 38 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 39 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 40 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 41 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 42 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 43 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 44 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 45 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 46 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 47 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 48 49 50 51 Introduction 52 ============ 53 54 Originally, hostapd was an optional user space component for Host AP 55 driver. It adds more features to the basic IEEE 802.11 management 56 included in the kernel driver: using external RADIUS authentication 57 server for MAC address based access control, IEEE 802.1X Authenticator 58 and dynamic WEP keying, RADIUS accounting, WPA/WPA2 (IEEE 802.11i/RSN) 59 Authenticator and dynamic TKIP/CCMP keying. 60 61 The current version includes support for other drivers, an integrated 62 EAP server (i.e., allow full authentication without requiring 63 an external RADIUS authentication server), and RADIUS authentication 64 server for EAP authentication. 65 66 67 Requirements 68 ------------ 69 70 Current 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 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 95 Build configuration 96 ------------------- 97 98 In order to be able to build hostapd, you will need to create a build 99 time configuration file, .config that selects which optional 100 components are included. See defconfig file for example configuration 101 and list of available options. 102 103 104 105 IEEE 802.1X 106 =========== 107 108 IEEE Std 802.1X-2001 is a standard for port-based network access 109 control. In case of IEEE 802.11 networks, a "virtual port" is used 110 between each associated station and the AP. IEEE 802.11 specifies 111 minimal authentication mechanism for stations, whereas IEEE 802.1X 112 introduces a extensible mechanism for authenticating and authorizing 113 users. 114 115 IEEE 802.1X uses elements called Supplicant, Authenticator, Port 116 Access Entity, and Authentication Server. Supplicant is a component in 117 a station and it performs the authentication with the Authentication 118 Server. An access point includes an Authenticator that relays the packets 119 between a Supplicant and an Authentication Server. In addition, it has a 120 Port Access Entity (PAE) with Authenticator functionality for 121 controlling the virtual port authorization, i.e., whether to accept 122 packets from or to the station. 123 124 IEEE 802.1X uses Extensible Authentication Protocol (EAP). The frames 125 between a Supplicant and an Authenticator are sent using EAP over LAN 126 (EAPOL) and the Authenticator relays these frames to the Authentication 127 Server (and similarly, relays the messages from the Authentication 128 Server to the Supplicant). The Authentication Server can be colocated with the 129 Authenticator, in which case there is no need for additional protocol 130 for EAP frame transmission. However, a more common configuration is to 131 use an external Authentication Server and encapsulate EAP frame in the 132 frames used by that server. RADIUS is suitable for this, but IEEE 133 802.1X would also allow other mechanisms. 134 135 Host AP driver includes PAE functionality in the kernel driver. It 136 is a relatively simple mechanism for denying normal frames going to 137 or coming from an unauthorized port. PAE allows IEEE 802.1X related 138 frames to be passed between the Supplicant and the Authenticator even 139 on an unauthorized port. 140 141 User space daemon, hostapd, includes Authenticator functionality. It 142 receives 802.1X (EAPOL) frames from the Supplicant using the wlan#ap 143 device that is also used with IEEE 802.11 management frames. The 144 frames to the Supplicant are sent using the same device. 145 146 The normal configuration of the Authenticator would use an external 147 Authentication Server. hostapd supports RADIUS encapsulation of EAP 148 packets, so the Authentication Server should be a RADIUS server, like 149 FreeRADIUS (http://www.freeradius.org/). The Authenticator in hostapd 150 relays the frames between the Supplicant and the Authentication 151 Server. It also controls the PAE functionality in the kernel driver by 152 controlling virtual port authorization, i.e., station-AP 153 connection, based on the IEEE 802.1X state. 154 155 When a station would like to use the services of an access point, it 156 will first perform IEEE 802.11 authentication. This is normally done 157 with open systems authentication, so there is no security. After 158 this, IEEE 802.11 association is performed. If IEEE 802.1X is 159 configured to be used, the virtual port for the station is set in 160 Unauthorized state and only IEEE 802.1X frames are accepted at this 161 point. The Authenticator will then ask the Supplicant to authenticate 162 with the Authentication Server. After this is completed successfully, 163 the virtual port is set to Authorized state and frames from and to the 164 station are accepted. 165 166 Host AP configuration for IEEE 802.1X 167 ------------------------------------- 168 169 The user space daemon has its own configuration file that can be used to 170 define AP options. Distribution package contains an example 171 configuration file (hostapd/hostapd.conf) that can be used as a basis 172 for configuration. It includes examples of all supported configuration 173 options and short description of each option. hostapd should be started 174 with full path to the configuration file as the command line argument, 175 e.g., './hostapd /etc/hostapd.conf'. If you have more that one wireless 176 LAN card, you can use one hostapd process for multiple interfaces by 177 giving a list of configuration files (one per interface) in the command 178 line. 179 180 hostapd includes a minimal co-located IEEE 802.1X server which can be 181 used to test IEEE 802.1X authentication. However, it should not be 182 used in normal use since it does not provide any security. This can be 183 configured by setting ieee8021x and minimal_eap options in the 184 configuration file. 185 186 An external Authentication Server (RADIUS) is configured with 187 auth_server_{addr,port,shared_secret} options. In addition, 188 ieee8021x and own_ip_addr must be set for this mode. With such 189 configuration, the co-located Authentication Server is not used and EAP 190 frames will be relayed using EAPOL between the Supplicant and the 191 Authenticator and RADIUS encapsulation between the Authenticator and 192 the Authentication Server. Other than this, the functionality is similar 193 to the case with the co-located Authentication Server. 194 195 Authentication Server and Supplicant 196 ------------------------------------ 197 198 Any RADIUS server supporting EAP should be usable as an IEEE 802.1X 199 Authentication Server with hostapd Authenticator. FreeRADIUS 200 (http://www.freeradius.org/) has been successfully tested with hostapd 201 Authenticator and both Xsupplicant (http://www.open1x.org) and Windows 202 XP Supplicants. EAP/TLS was used with Xsupplicant and 203 EAP/MD5-Challenge with Windows XP. 204 205 http://www.missl.cs.umd.edu/wireless/eaptls/ has useful information 206 about using EAP/TLS with FreeRADIUS and Xsupplicant (just replace 207 Cisco access point with Host AP driver, hostapd daemon, and a Prism2 208 card ;-). http://www.freeradius.org/doc/EAP-MD5.html has information 209 about using EAP/MD5 with FreeRADIUS, including instructions for WinXP 210 configuration. http://www.denobula.com/EAPTLS.pdf has a HOWTO on 211 EAP/TLS use with WinXP Supplicant. 212 213 Automatic WEP key configuration 214 ------------------------------- 215 216 EAP/TLS generates a session key that can be used to send WEP keys from 217 an AP to authenticated stations. The Authenticator in hostapd can be 218 configured to automatically select a random default/broadcast key 219 (shared by all authenticated stations) with wep_key_len_broadcast 220 option (5 for 40-bit WEP or 13 for 104-bit WEP). In addition, 221 wep_key_len_unicast option can be used to configure individual unicast 222 keys for stations. This requires support for individual keys in the 223 station driver. 224 225 WEP keys can be automatically updated by configuring rekeying. This 226 will improve security of the network since same WEP key will only be 227 used for a limited period of time. wep_rekey_period option sets the 228 interval for rekeying in seconds. 229 230 231 WPA/WPA2 232 ======== 233 234 Features 235 -------- 236 237 Supported 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 242 243 WPA 244 --- 245 246 The original security mechanism of IEEE 802.11 standard was not 247 designed to be strong and has proved to be insufficient for most 248 networks that require some kind of security. Task group I (Security) 249 of IEEE 802.11 working group (http://www.ieee802.org/11/) has worked 250 to address the flaws of the base standard and has in practice 251 completed its work in May 2004. The IEEE 802.11i amendment to the IEEE 252 802.11 standard was approved in June 2004 and this amendment is likely 253 to be published in July 2004. 254 255 Wi-Fi Alliance (http://www.wi-fi.org/) used a draft version of the 256 IEEE 802.11i work (draft 3.0) to define a subset of the security 257 enhancements that can be implemented with existing wlan hardware. This 258 is called Wi-Fi Protected Access<TM> (WPA). This has now become a 259 mandatory component of interoperability testing and certification done 260 by Wi-Fi Alliance. Wi-Fi provides information about WPA at its web 261 site (http://www.wi-fi.org/OpenSection/protected_access.asp). 262 263 IEEE 802.11 standard defined wired equivalent privacy (WEP) algorithm 264 for protecting wireless networks. WEP uses RC4 with 40-bit keys, 265 24-bit initialization vector (IV), and CRC32 to protect against packet 266 forgery. All these choices have proven to be insufficient: key space is 267 too small against current attacks, RC4 key scheduling is insufficient 268 (beginning of the pseudorandom stream should be skipped), IV space is 269 too small and IV reuse makes attacks easier, there is no replay 270 protection, and non-keyed authentication does not protect against bit 271 flipping packet data. 272 273 WPA is an intermediate solution for the security issues. It uses 274 Temporal Key Integrity Protocol (TKIP) to replace WEP. TKIP is a 275 compromise on strong security and possibility to use existing 276 hardware. It still uses RC4 for the encryption like WEP, but with 277 per-packet RC4 keys. In addition, it implements replay protection, 278 keyed packet authentication mechanism (Michael MIC). 279 280 Keys can be managed using two different mechanisms. WPA can either use 281 an external authentication server (e.g., RADIUS) and EAP just like 282 IEEE 802.1X is using or pre-shared keys without need for additional 283 servers. Wi-Fi calls these "WPA-Enterprise" and "WPA-Personal", 284 respectively. Both mechanisms will generate a master session key for 285 the Authenticator (AP) and Supplicant (client station). 286 287 WPA implements a new key handshake (4-Way Handshake and Group Key 288 Handshake) for generating and exchanging data encryption keys between 289 the Authenticator and Supplicant. This handshake is also used to 290 verify that both Authenticator and Supplicant know the master session 291 key. These handshakes are identical regardless of the selected key 292 management mechanism (only the method for generating master session 293 key changes). 294 295 296 IEEE 802.11i / WPA2 297 ------------------- 298 299 The design for parts of IEEE 802.11i that were not included in WPA has 300 finished (May 2004) and this amendment to IEEE 802.11 was approved in 301 June 2004. Wi-Fi Alliance is using the final IEEE 802.11i as a new 302 version of WPA called WPA2. This includes, e.g., support for more 303 robust encryption algorithm (CCMP: AES in Counter mode with CBC-MAC) 304 to replace TKIP and optimizations for handoff (reduced number of 305 messages in initial key handshake, pre-authentication, and PMKSA caching). 306 307 Some wireless LAN vendors are already providing support for CCMP in 308 their WPA products. There is no "official" interoperability 309 certification for CCMP and/or mixed modes using both TKIP and CCMP, so 310 some interoperability issues can be expected even though many 311 combinations seem to be working with equipment from different vendors. 312 Testing for WPA2 is likely to start during the second half of 2004. 313 314 hostapd configuration for WPA/WPA2 315 ---------------------------------- 316 317 TODO 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 373