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) 2002-2017, 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://w1.fi/hostap-driver.html) 74 Please note that station firmware version needs to be 1.7.0 or newer 75 to work in WPA mode. 76 77 mac80211-based drivers that support AP mode (with driver=nl80211). 78 This includes drivers for Atheros (ath9k) and Broadcom (b43) 79 chipsets. 80 81 Any wired Ethernet driver for wired IEEE 802.1X authentication 82 (experimental code) 83 84 FreeBSD -current 85 BSD net80211 layer (e.g., Atheros driver) 86 87 88 Build configuration 89 ------------------- 90 91 In order to be able to build hostapd, you will need to create a build 92 time configuration file, .config that selects which optional 93 components are included. See defconfig file for example configuration 94 and list of available options. 95 96 97 98 IEEE 802.1X 99 =========== 100 101 IEEE Std 802.1X-2001 is a standard for port-based network access 102 control. In case of IEEE 802.11 networks, a "virtual port" is used 103 between each associated station and the AP. IEEE 802.11 specifies 104 minimal authentication mechanism for stations, whereas IEEE 802.1X 105 introduces a extensible mechanism for authenticating and authorizing 106 users. 107 108 IEEE 802.1X uses elements called Supplicant, Authenticator, Port 109 Access Entity, and Authentication Server. Supplicant is a component in 110 a station and it performs the authentication with the Authentication 111 Server. An access point includes an Authenticator that relays the packets 112 between a Supplicant and an Authentication Server. In addition, it has a 113 Port Access Entity (PAE) with Authenticator functionality for 114 controlling the virtual port authorization, i.e., whether to accept 115 packets from or to the station. 116 117 IEEE 802.1X uses Extensible Authentication Protocol (EAP). The frames 118 between a Supplicant and an Authenticator are sent using EAP over LAN 119 (EAPOL) and the Authenticator relays these frames to the Authentication 120 Server (and similarly, relays the messages from the Authentication 121 Server to the Supplicant). The Authentication Server can be colocated with the 122 Authenticator, in which case there is no need for additional protocol 123 for EAP frame transmission. However, a more common configuration is to 124 use an external Authentication Server and encapsulate EAP frame in the 125 frames used by that server. RADIUS is suitable for this, but IEEE 126 802.1X would also allow other mechanisms. 127 128 Host AP driver includes PAE functionality in the kernel driver. It 129 is a relatively simple mechanism for denying normal frames going to 130 or coming from an unauthorized port. PAE allows IEEE 802.1X related 131 frames to be passed between the Supplicant and the Authenticator even 132 on an unauthorized port. 133 134 User space daemon, hostapd, includes Authenticator functionality. It 135 receives 802.1X (EAPOL) frames from the Supplicant using the wlan#ap 136 device that is also used with IEEE 802.11 management frames. The 137 frames to the Supplicant are sent using the same device. 138 139 The normal configuration of the Authenticator would use an external 140 Authentication Server. hostapd supports RADIUS encapsulation of EAP 141 packets, so the Authentication Server should be a RADIUS server, like 142 FreeRADIUS (http://www.freeradius.org/). The Authenticator in hostapd 143 relays the frames between the Supplicant and the Authentication 144 Server. It also controls the PAE functionality in the kernel driver by 145 controlling virtual port authorization, i.e., station-AP 146 connection, based on the IEEE 802.1X state. 147 148 When a station would like to use the services of an access point, it 149 will first perform IEEE 802.11 authentication. This is normally done 150 with open systems authentication, so there is no security. After 151 this, IEEE 802.11 association is performed. If IEEE 802.1X is 152 configured to be used, the virtual port for the station is set in 153 Unauthorized state and only IEEE 802.1X frames are accepted at this 154 point. The Authenticator will then ask the Supplicant to authenticate 155 with the Authentication Server. After this is completed successfully, 156 the virtual port is set to Authorized state and frames from and to the 157 station are accepted. 158 159 Host AP configuration for IEEE 802.1X 160 ------------------------------------- 161 162 The user space daemon has its own configuration file that can be used to 163 define AP options. Distribution package contains an example 164 configuration file (hostapd/hostapd.conf) that can be used as a basis 165 for configuration. It includes examples of all supported configuration 166 options and short description of each option. hostapd should be started 167 with full path to the configuration file as the command line argument, 168 e.g., './hostapd /etc/hostapd.conf'. If you have more that one wireless 169 LAN card, you can use one hostapd process for multiple interfaces by 170 giving a list of configuration files (one per interface) in the command 171 line. 172 173 hostapd includes a minimal co-located IEEE 802.1X server which can be 174 used to test IEEE 802.1X authentication. However, it should not be 175 used in normal use since it does not provide any security. This can be 176 configured by setting ieee8021x and minimal_eap options in the 177 configuration file. 178 179 An external Authentication Server (RADIUS) is configured with 180 auth_server_{addr,port,shared_secret} options. In addition, 181 ieee8021x and own_ip_addr must be set for this mode. With such 182 configuration, the co-located Authentication Server is not used and EAP 183 frames will be relayed using EAPOL between the Supplicant and the 184 Authenticator and RADIUS encapsulation between the Authenticator and 185 the Authentication Server. Other than this, the functionality is similar 186 to the case with the co-located Authentication Server. 187 188 Authentication Server 189 --------------------- 190 191 Any RADIUS server supporting EAP should be usable as an IEEE 802.1X 192 Authentication Server with hostapd Authenticator. FreeRADIUS 193 (http://www.freeradius.org/) has been successfully tested with hostapd 194 Authenticator. 195 196 Automatic WEP key configuration 197 ------------------------------- 198 199 EAP/TLS generates a session key that can be used to send WEP keys from 200 an AP to authenticated stations. The Authenticator in hostapd can be 201 configured to automatically select a random default/broadcast key 202 (shared by all authenticated stations) with wep_key_len_broadcast 203 option (5 for 40-bit WEP or 13 for 104-bit WEP). In addition, 204 wep_key_len_unicast option can be used to configure individual unicast 205 keys for stations. This requires support for individual keys in the 206 station driver. 207 208 WEP keys can be automatically updated by configuring rekeying. This 209 will improve security of the network since same WEP key will only be 210 used for a limited period of time. wep_rekey_period option sets the 211 interval for rekeying in seconds. 212 213 214 WPA/WPA2 215 ======== 216 217 Features 218 -------- 219 220 Supported WPA/IEEE 802.11i features: 221 - WPA-PSK ("WPA-Personal") 222 - WPA with EAP (e.g., with RADIUS authentication server) ("WPA-Enterprise") 223 - key management for CCMP, TKIP, WEP104, WEP40 224 - RSN/WPA2 (IEEE 802.11i), including PMKSA caching and pre-authentication 225 226 WPA 227 --- 228 229 The original security mechanism of IEEE 802.11 standard was not 230 designed to be strong and has proved to be insufficient for most 231 networks that require some kind of security. Task group I (Security) 232 of IEEE 802.11 working group (http://www.ieee802.org/11/) has worked 233 to address the flaws of the base standard and has in practice 234 completed its work in May 2004. The IEEE 802.11i amendment to the IEEE 235 802.11 standard was approved in June 2004 and this amendment was 236 published in July 2004. 237 238 Wi-Fi Alliance (http://www.wi-fi.org/) used a draft version of the 239 IEEE 802.11i work (draft 3.0) to define a subset of the security 240 enhancements that can be implemented with existing wlan hardware. This 241 is called Wi-Fi Protected Access<TM> (WPA). This has now become a 242 mandatory component of interoperability testing and certification done 243 by Wi-Fi Alliance. 244 245 IEEE 802.11 standard defined wired equivalent privacy (WEP) algorithm 246 for protecting wireless networks. WEP uses RC4 with 40-bit keys, 247 24-bit initialization vector (IV), and CRC32 to protect against packet 248 forgery. All these choices have proven to be insufficient: key space is 249 too small against current attacks, RC4 key scheduling is insufficient 250 (beginning of the pseudorandom stream should be skipped), IV space is 251 too small and IV reuse makes attacks easier, there is no replay 252 protection, and non-keyed authentication does not protect against bit 253 flipping packet data. 254 255 WPA is an intermediate solution for the security issues. It uses 256 Temporal Key Integrity Protocol (TKIP) to replace WEP. TKIP is a 257 compromise on strong security and possibility to use existing 258 hardware. It still uses RC4 for the encryption like WEP, but with 259 per-packet RC4 keys. In addition, it implements replay protection, 260 keyed packet authentication mechanism (Michael MIC). 261 262 Keys can be managed using two different mechanisms. WPA can either use 263 an external authentication server (e.g., RADIUS) and EAP just like 264 IEEE 802.1X is using or pre-shared keys without need for additional 265 servers. Wi-Fi calls these "WPA-Enterprise" and "WPA-Personal", 266 respectively. Both mechanisms will generate a master session key for 267 the Authenticator (AP) and Supplicant (client station). 268 269 WPA implements a new key handshake (4-Way Handshake and Group Key 270 Handshake) for generating and exchanging data encryption keys between 271 the Authenticator and Supplicant. This handshake is also used to 272 verify that both Authenticator and Supplicant know the master session 273 key. These handshakes are identical regardless of the selected key 274 management mechanism (only the method for generating master session 275 key changes). 276 277 278 IEEE 802.11i / WPA2 279 ------------------- 280 281 The design for parts of IEEE 802.11i that were not included in WPA has 282 finished (May 2004) and this amendment to IEEE 802.11 was approved in 283 June 2004. Wi-Fi Alliance is using the final IEEE 802.11i as a new 284 version of WPA called WPA2. This includes, e.g., support for more 285 robust encryption algorithm (CCMP: AES in Counter mode with CBC-MAC) 286 to replace TKIP and optimizations for handoff (reduced number of 287 messages in initial key handshake, pre-authentication, and PMKSA caching). 288 289 Some wireless LAN vendors are already providing support for CCMP in 290 their WPA products. There is no "official" interoperability 291 certification for CCMP and/or mixed modes using both TKIP and CCMP, so 292 some interoperability issues can be expected even though many 293 combinations seem to be working with equipment from different vendors. 294 Testing for WPA2 is likely to start during the second half of 2004. 295 296 hostapd configuration for WPA/WPA2 297 ---------------------------------- 298 299 TODO 300 301 # Enable WPA. Setting this variable configures the AP to require WPA (either 302 # WPA-PSK or WPA-RADIUS/EAP based on other configuration). For WPA-PSK, either 303 # wpa_psk or wpa_passphrase must be set and wpa_key_mgmt must include WPA-PSK. 304 # For WPA-RADIUS/EAP, ieee8021x must be set (but without dynamic WEP keys), 305 # RADIUS authentication server must be configured, and WPA-EAP must be included 306 # in wpa_key_mgmt. 307 # This field is a bit field that can be used to enable WPA (IEEE 802.11i/D3.0) 308 # and/or WPA2 (full IEEE 802.11i/RSN): 309 # bit0 = WPA 310 # bit1 = IEEE 802.11i/RSN (WPA2) 311 #wpa=1 312 313 # WPA pre-shared keys for WPA-PSK. This can be either entered as a 256-bit 314 # secret in hex format (64 hex digits), wpa_psk, or as an ASCII passphrase 315 # (8..63 characters) that will be converted to PSK. This conversion uses SSID 316 # so the PSK changes when ASCII passphrase is used and the SSID is changed. 317 #wpa_psk=0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef 318 #wpa_passphrase=secret passphrase 319 320 # Set of accepted key management algorithms (WPA-PSK, WPA-EAP, or both). The 321 # entries are separated with a space. 322 #wpa_key_mgmt=WPA-PSK WPA-EAP 323 324 # Set of accepted cipher suites (encryption algorithms) for pairwise keys 325 # (unicast packets). This is a space separated list of algorithms: 326 # CCMP = AES in Counter mode with CBC-MAC [RFC 3610, IEEE 802.11i] 327 # TKIP = Temporal Key Integrity Protocol [IEEE 802.11i] 328 # Group cipher suite (encryption algorithm for broadcast and multicast frames) 329 # is automatically selected based on this configuration. If only CCMP is 330 # allowed as the pairwise cipher, group cipher will also be CCMP. Otherwise, 331 # TKIP will be used as the group cipher. 332 #wpa_pairwise=TKIP CCMP 333 334 # Time interval for rekeying GTK (broadcast/multicast encryption keys) in 335 # seconds. 336 #wpa_group_rekey=600 337 338 # Time interval for rekeying GMK (master key used internally to generate GTKs 339 # (in seconds). 340 #wpa_gmk_rekey=86400 341 342 # Enable IEEE 802.11i/RSN/WPA2 pre-authentication. This is used to speed up 343 # roaming be pre-authenticating IEEE 802.1X/EAP part of the full RSN 344 # authentication and key handshake before actually associating with a new AP. 345 #rsn_preauth=1 346 # 347 # Space separated list of interfaces from which pre-authentication frames are 348 # accepted (e.g., 'eth0' or 'eth0 wlan0wds0'. This list should include all 349 # interface that are used for connections to other APs. This could include 350 # wired interfaces and WDS links. The normal wireless data interface towards 351 # associated stations (e.g., wlan0) should not be added, since 352 # pre-authentication is only used with APs other than the currently associated 353 # one. 354 #rsn_preauth_interfaces=eth0 355
