1hostapd - user space IEEE 802.11 AP and IEEE 802.1X/WPA/WPA2/EAP 2 Authenticator and RADIUS authentication server 3================================================================ 4 5Copyright (c) 2002-2022, Jouni Malinen <j@w1.fi> and contributors 6All Rights Reserved. 7 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. 13 14 15 16License 17------- 18 19This software may be distributed, used, and modified under the terms of 20BSD license: 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://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 88Build configuration 89------------------- 90 91In order to be able to build hostapd, you will need to create a build 92time configuration file, .config that selects which optional 93components are included. See defconfig file for example configuration 94and list of available options. 95 96 97 98IEEE 802.1X 99=========== 100 101IEEE Std 802.1X-2001 is a standard for port-based network access 102control. In case of IEEE 802.11 networks, a "virtual port" is used 103between each associated station and the AP. IEEE 802.11 specifies 104minimal authentication mechanism for stations, whereas IEEE 802.1X 105introduces a extensible mechanism for authenticating and authorizing 106users. 107 108IEEE 802.1X uses elements called Supplicant, Authenticator, Port 109Access Entity, and Authentication Server. Supplicant is a component in 110a station and it performs the authentication with the Authentication 111Server. An access point includes an Authenticator that relays the packets 112between a Supplicant and an Authentication Server. In addition, it has a 113Port Access Entity (PAE) with Authenticator functionality for 114controlling the virtual port authorization, i.e., whether to accept 115packets from or to the station. 116 117IEEE 802.1X uses Extensible Authentication Protocol (EAP). The frames 118between a Supplicant and an Authenticator are sent using EAP over LAN 119(EAPOL) and the Authenticator relays these frames to the Authentication 120Server (and similarly, relays the messages from the Authentication 121Server to the Supplicant). The Authentication Server can be colocated with the 122Authenticator, in which case there is no need for additional protocol 123for EAP frame transmission. However, a more common configuration is to 124use an external Authentication Server and encapsulate EAP frame in the 125frames used by that server. RADIUS is suitable for this, but IEEE 126802.1X would also allow other mechanisms. 127 128Host AP driver includes PAE functionality in the kernel driver. It 129is a relatively simple mechanism for denying normal frames going to 130or coming from an unauthorized port. PAE allows IEEE 802.1X related 131frames to be passed between the Supplicant and the Authenticator even 132on an unauthorized port. 133 134User space daemon, hostapd, includes Authenticator functionality. It 135receives 802.1X (EAPOL) frames from the Supplicant using the wlan#ap 136device that is also used with IEEE 802.11 management frames. The 137frames to the Supplicant are sent using the same device. 138 139The normal configuration of the Authenticator would use an external 140Authentication Server. hostapd supports RADIUS encapsulation of EAP 141packets, so the Authentication Server should be a RADIUS server, like 142FreeRADIUS (http://www.freeradius.org/). The Authenticator in hostapd 143relays the frames between the Supplicant and the Authentication 144Server. It also controls the PAE functionality in the kernel driver by 145controlling virtual port authorization, i.e., station-AP 146connection, based on the IEEE 802.1X state. 147 148When a station would like to use the services of an access point, it 149will first perform IEEE 802.11 authentication. This is normally done 150with open systems authentication, so there is no security. After 151this, IEEE 802.11 association is performed. If IEEE 802.1X is 152configured to be used, the virtual port for the station is set in 153Unauthorized state and only IEEE 802.1X frames are accepted at this 154point. The Authenticator will then ask the Supplicant to authenticate 155with the Authentication Server. After this is completed successfully, 156the virtual port is set to Authorized state and frames from and to the 157station are accepted. 158 159Host AP configuration for IEEE 802.1X 160------------------------------------- 161 162The user space daemon has its own configuration file that can be used to 163define AP options. Distribution package contains an example 164configuration file (hostapd/hostapd.conf) that can be used as a basis 165for configuration. It includes examples of all supported configuration 166options and short description of each option. hostapd should be started 167with full path to the configuration file as the command line argument, 168e.g., './hostapd /etc/hostapd.conf'. If you have more that one wireless 169LAN card, you can use one hostapd process for multiple interfaces by 170giving a list of configuration files (one per interface) in the command 171line. 172 173hostapd includes a minimal co-located IEEE 802.1X server which can be 174used to test IEEE 802.1X authentication. However, it should not be 175used in normal use since it does not provide any security. This can be 176configured by setting ieee8021x and minimal_eap options in the 177configuration file. 178 179An external Authentication Server (RADIUS) is configured with 180auth_server_{addr,port,shared_secret} options. In addition, 181ieee8021x and own_ip_addr must be set for this mode. With such 182configuration, the co-located Authentication Server is not used and EAP 183frames will be relayed using EAPOL between the Supplicant and the 184Authenticator and RADIUS encapsulation between the Authenticator and 185the Authentication Server. Other than this, the functionality is similar 186to the case with the co-located Authentication Server. 187 188Authentication Server 189--------------------- 190 191Any RADIUS server supporting EAP should be usable as an IEEE 802.1X 192Authentication Server with hostapd Authenticator. FreeRADIUS 193(http://www.freeradius.org/) has been successfully tested with hostapd 194Authenticator. 195 196Automatic WEP key configuration 197------------------------------- 198 199EAP/TLS generates a session key that can be used to send WEP keys from 200an AP to authenticated stations. The Authenticator in hostapd can be 201configured to automatically select a random default/broadcast key 202(shared by all authenticated stations) with wep_key_len_broadcast 203option (5 for 40-bit WEP or 13 for 104-bit WEP). In addition, 204wep_key_len_unicast option can be used to configure individual unicast 205keys for stations. This requires support for individual keys in the 206station driver. 207 208WEP keys can be automatically updated by configuring rekeying. This 209will improve security of the network since same WEP key will only be 210used for a limited period of time. wep_rekey_period option sets the 211interval for rekeying in seconds. 212 213 214WPA/WPA2 215======== 216 217Features 218-------- 219 220Supported 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 226WPA 227--- 228 229The original security mechanism of IEEE 802.11 standard was not 230designed to be strong and has proved to be insufficient for most 231networks that require some kind of security. Task group I (Security) 232of IEEE 802.11 working group (http://www.ieee802.org/11/) has worked 233to address the flaws of the base standard and has in practice 234completed its work in May 2004. The IEEE 802.11i amendment to the IEEE 235802.11 standard was approved in June 2004 and this amendment was 236published in July 2004. 237 238Wi-Fi Alliance (http://www.wi-fi.org/) used a draft version of the 239IEEE 802.11i work (draft 3.0) to define a subset of the security 240enhancements that can be implemented with existing wlan hardware. This 241is called Wi-Fi Protected Access<TM> (WPA). This has now become a 242mandatory component of interoperability testing and certification done 243by Wi-Fi Alliance. 244 245IEEE 802.11 standard defined wired equivalent privacy (WEP) algorithm 246for protecting wireless networks. WEP uses RC4 with 40-bit keys, 24724-bit initialization vector (IV), and CRC32 to protect against packet 248forgery. All these choices have proven to be insufficient: key space is 249too small against current attacks, RC4 key scheduling is insufficient 250(beginning of the pseudorandom stream should be skipped), IV space is 251too small and IV reuse makes attacks easier, there is no replay 252protection, and non-keyed authentication does not protect against bit 253flipping packet data. 254 255WPA is an intermediate solution for the security issues. It uses 256Temporal Key Integrity Protocol (TKIP) to replace WEP. TKIP is a 257compromise on strong security and possibility to use existing 258hardware. It still uses RC4 for the encryption like WEP, but with 259per-packet RC4 keys. In addition, it implements replay protection, 260keyed packet authentication mechanism (Michael MIC). 261 262Keys can be managed using two different mechanisms. WPA can either use 263an external authentication server (e.g., RADIUS) and EAP just like 264IEEE 802.1X is using or pre-shared keys without need for additional 265servers. Wi-Fi calls these "WPA-Enterprise" and "WPA-Personal", 266respectively. Both mechanisms will generate a master session key for 267the Authenticator (AP) and Supplicant (client station). 268 269WPA implements a new key handshake (4-Way Handshake and Group Key 270Handshake) for generating and exchanging data encryption keys between 271the Authenticator and Supplicant. This handshake is also used to 272verify that both Authenticator and Supplicant know the master session 273key. These handshakes are identical regardless of the selected key 274management mechanism (only the method for generating master session 275key changes). 276 277 278IEEE 802.11i / WPA2 279------------------- 280 281The design for parts of IEEE 802.11i that were not included in WPA has 282finished (May 2004) and this amendment to IEEE 802.11 was approved in 283June 2004. Wi-Fi Alliance is using the final IEEE 802.11i as a new 284version of WPA called WPA2. This includes, e.g., support for more 285robust encryption algorithm (CCMP: AES in Counter mode with CBC-MAC) 286to replace TKIP and optimizations for handoff (reduced number of 287messages in initial key handshake, pre-authentication, and PMKSA caching). 288 289Some wireless LAN vendors are already providing support for CCMP in 290their WPA products. There is no "official" interoperability 291certification for CCMP and/or mixed modes using both TKIP and CCMP, so 292some interoperability issues can be expected even though many 293combinations seem to be working with equipment from different vendors. 294Testing for WPA2 is likely to start during the second half of 2004. 295 296hostapd configuration for WPA/WPA2 297---------------------------------- 298 299TODO 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
