docs/wireless.tex

   1 The WiFi settings are configured in the file \texttt{/etc/config/wireless}
   2 (currently supported on Broadcom, Atheros and mac80211). When booting the router for the first time
   3 it should detect your card and create a sample configuration file. By default '\texttt{option network  lan}' is
   4 commented. This prevents unsecured sharing of the network over the wireless interface.
   5
   6 Each wireless driver has its own configuration script in \texttt{/lib/wifi/driver\_name.sh} which handles
   7 driver specific options and configurations. This script is also calling driver specific binaries like wlc for
   8 Broadcom, or hostapd and wpa\_supplicant for atheros.
   9
  10 The reason for using such architecture, is that it abstracts the driver configuration.
  11
  12 \paragraph{Generic Broadcom wireless config:}
  13
  14 \begin{Verbatim}
  15 config wifi-device      "wl0"
  16     option type         "broadcom"
  17     option channel      "5"
  18
  19 config wifi-iface
  20     option device       "wl0"
  21 #   option network  lan
  22     option mode         "ap"
  23     option ssid         "OpenWrt"
  24     option hidden       "0"
  25     option encryption   "none"
  26 \end{Verbatim}
  27
  28 \paragraph{Generic Atheros wireless config:}
  29
  30 \begin{Verbatim}
  31 config wifi-device      "wifi0"
  32     option type         "atheros"
  33     option channel      "5"
  34     option hwmode       "11g"
  35
  36 config wifi-iface
  37     option device       "wifi0"
  38 #   option network  lan
  39     option mode         "ap"
  40     option ssid         "OpenWrt"
  41     option hidden       "0"
  42     option encryption   "none"
  43 \end{Verbatim}
  44
  45 \paragraph{Generic mac80211 wireless config:}
  46
  47 \begin{Verbatim}
  48 config wifi-device      "wifi0"
  49     option type         "mac80211"
  50     option channel      "5"
  51
  52 config wifi-iface
  53     option device       "wlan0"
  54 #   option network  lan
  55     option mode         "ap"
  56     option ssid         "OpenWrt"
  57     option hidden       "0"
  58     option encryption   "none"
  59 \end{Verbatim}
  60
  61 \paragraph{Generic multi-radio Atheros wireless config:}
  62
  63 \begin{Verbatim}
  64 config wifi-device  wifi0
  65     option type     atheros
  66     option channel  1
  67
  68 config wifi-iface
  69     option device   wifi0
  70 #   option network  lan
  71     option mode     ap
  72     option ssid     OpenWrt_private
  73     option hidden   0
  74     option encryption none
  75
  76 config wifi-device  wifi1
  77     option type     atheros
  78     option channel  11
  79
  80 config wifi-iface
  81     option device   wifi1
  82 #   option network  lan
  83     option mode     ap
  84     option ssid     OpenWrt_public
  85     option hidden   1
  86     option encryption none
  87 \end{Verbatim}
  88
  89 There are two types of config sections in this file. The '\texttt{wifi-device}' refers to
  90 the physical wifi interface and '\texttt{wifi-iface}' configures a virtual interface on top
  91 of that (if supported by the driver).
  92
  93 A full outline of the wireless configuration file with description of each field:
  94
  95 \begin{Verbatim}
  96 config wifi-device    wifi device name
  97     option type       broadcom, atheros, mac80211
  98     option country    us, uk, fr, de, etc.
  99     option channel    1-14
 100     option maxassoc   1-128 (broadcom only)
 101     option distance   1-n
 102     option hwmode     11b, 11g, 11a, 11bg (atheros, mac80211)
 103     option rxantenna  0,1,2 (atheros, broadcom)
 104     option txantenna  0,1,2 (atheros, broadcom)
 105     option txpower  transmission power in dBm
 106
 107 config wifi-iface
 108     option network  the interface you want wifi to bridge with
 109     option device   wifi0, wifi1, wifi2, wifiN
 110     option mode     ap, sta, adhoc, monitor, or wds
 111     option txpower  (deprecated) transmission power in dBm
 112     option ssid     ssid name
 113     option bssid    bssid address
 114     option encryption none, wep, psk, psk2, wpa, wpa2
 115     option key      encryption key
 116     option key1     key 1
 117     option key2     key 2
 118     option key3     key 3
 119     option key4     key 4
 120     option server   ip address
 121     option port     port
 122     option hidden   0,1
 123     option isolate  0,1
 124 \end{Verbatim}
 125
 126 \paragraph{Options for the \texttt{wifi-device}:}
 127
 128 \begin{itemize}
 129     \item \texttt{type} \\
 130         The driver to use for this interface.
 131
 132     \item \texttt{country} \\
 133         The country code used to determine the regulatory settings.
 134
 135     \item \texttt{channel} \\
 136         The wifi channel (e.g. 1-14, depending on your country setting).
 137
 138     \item \texttt{maxassoc} \\
 139         Optional: Maximum number of associated clients. This feature is supported only on the broadcom chipset.
 140
 141     \item \texttt{distance} \\
 142         Optional: Distance between the ap and the furthest client in meters. This feature is supported only on the atheros chipset.
 143
 144         \item \texttt{mode} \\
 145                 The frequency band (\texttt{b}, \texttt{g}, \texttt{bg}, \texttt{a}). This feature is only supported on the atheros chipset.
 146
 147     \item \texttt{diversity} \\
 148         Optional: Enable diversity for the Wi-Fi device. This feature is supported only on the atheros chipset.
 149
 150     \item \texttt{rxantenna} \\
 151         Optional: Antenna identifier (0, 1 or 2) for reception. This feature is supported by atheros and some broadcom chipsets.
 152
 153     \item \texttt{txantenna} \\
 154         Optional: Antenna identifier (0, 1 or 2) for emission. This feature is supported by atheros and some broadcom chipsets.
 155
 156     \item \texttt{txpower}
 157         Set the transmission power to be used. The amount is specified in dBm.
 158
 159 \end{itemize}
 160
 161 \paragraph{Options for the \texttt{wifi-iface}:}
 162
 163 \begin{itemize}
 164     \item \texttt{network} \\
 165         Selects the interface section from \texttt{/etc/config/network} to be
 166         used with this interface
 167
 168     \item \texttt{device} \\
 169         Set the wifi device name.
 170
 171     \item \texttt{mode} \\
 172         Operating mode:
 173
 174         \begin{itemize}
 175             \item \texttt{ap} \\
 176                 Access point mode
 177
 178             \item \texttt{sta} \\
 179                 Client mode
 180
 181             \item \texttt{adhoc} \\
 182                 Ad-Hoc mode
 183
 184             \item \texttt{monitor} \\
 185                 Monitor mode
 186
 187             \item \texttt{wds} \\
 188                 WDS point-to-point link
 189
 190         \end{itemize}
 191
 192     \item \texttt{ssid}
 193         Set the SSID to be used on the wifi device.
 194
 195     \item \texttt{bssid}
 196         Set the BSSID address to be used for wds to set the mac address of the other wds unit.
 197
 198     \item \texttt{txpower}
 199         (Deprecated, set in wifi-device) Set the transmission power to be used. The amount is specified in dBm.
 200
 201     \item \texttt{encryption} \\
 202         Encryption setting. Accepts the following values:
 203
 204         \begin{itemize}
 205             \item \texttt{none}
 206             \item \texttt{wep}
 207             \item \texttt{psk}, \texttt{psk2} \\
 208                 WPA(2) Pre-shared Key
 209
 210             \item \texttt{wpa}, \texttt{wpa2} \\
 211                 WPA(2) RADIUS
 212         \end{itemize}
 213
 214     \item \texttt{key, key1, key2, key3, key4} (wep, wpa and psk) \\
 215         WEP key, WPA key (PSK mode) or the RADIUS shared secret (WPA RADIUS mode)
 216
 217     \item \texttt{server} (wpa) \\
 218         The RADIUS server ip address
 219
 220     \item \texttt{port} (wpa) \\
 221         The RADIUS server port (defaults to 1812)
 222
 223     \item \texttt{hidden} \\
 224         0 broadcasts the ssid; 1 disables broadcasting of the ssid
 225
 226     \item \texttt{isolate} \\
 227         Optional: Isolation is a mode usually set on hotspots that limits the clients to communicate only with the AP and not with other wireless clients.
 228         0 disables ap isolation (default); 1 enables ap isolation.
 229
 230 \end{itemize}
 231
 232 \paragraph{Wireless Distribution System}
 233
 234 WDS is a non-standard mode which will be working between two Broadcom devices for instance
 235 but not between a Broadcom and Atheros device.
 236
 237 \subparagraph{Unencrypted WDS connections}
 238
 239 This configuration example shows you how to setup unencrypted WDS connections.
 240 We assume that the peer configured as below as the BSSID ca:fe:ba:be:00:01
 241 and the remote WDS endpoint ca:fe:ba:be:00:02 (option bssid field).
 242
 243 \begin{Verbatim}
 244 config wifi-device      "wl0"
 245     option type         "broadcom"
 246     option channel      "5"
 247
 248 config wifi-iface
 249     option device       "wl0"
 250     option network      lan
 251     option mode         "ap"
 252     option ssid         "OpenWrt"
 253     option hidden       "0"
 254     option encryption   "none"
 255
 256 config wifi-iface
 257     option device       "wl0"
 258     option network      lan
 259     option mode         wds
 260     option ssid         "OpenWrt WDS"
 261     option bssid        "ca:fe:ba:be:00:02"
 262 \end{Verbatim}
 263
 264 \subparagraph{Encrypted WDS connections}
 265
 266 It is also possible to encrypt WDS connections. \texttt{psk}, \texttt{psk2} and
 267 \texttt{psk+psk2} modes are supported. Configuration below is an example
 268 configuration using Pre-Shared-Keys with AES algorithm.
 269
 270 \begin{Verbatim}
 271 config wifi-device  wl0
 272     option type     broadcom
 273     option channel  5
 274
 275 config wifi-iface
 276     option device   "wl0"
 277     option network  lan
 278     option mode     ap
 279     option ssid     "OpenWrt"
 280     option encryption  psk2
 281     option key      "<key for clients>"
 282
 283 config wifi-iface
 284     option device   "wl0"
 285     option network  lan
 286     option mode     wds
 287     option bssid    ca:fe:ba:be:00:02
 288     option ssid     "OpenWrt WDS"
 289     option encryption   psk2
 290     option key      "<psk for WDS>"
 291 \end{Verbatim}
 292
 293 \paragraph{802.1x configurations}
 294
 295 OpenWrt supports both 802.1x client and Access Point
 296 configurations. 802.1x client is only working with
 297 Atheros or mac80211 drivers. Configuration only
 298 supports EAP types TLS, TTLS or PEAP.
 299
 300 \subparagraph{EAP-TLS}
 301
 302 \begin{Verbatim}
 303 config wifi-iface
 304     option device         "ath0"
 305     option network        lan
 306     option ssid           OpenWrt
 307     option eap_type       tls
 308     option ca_cert        "/etc/config/certs/ca.crt"
 309     option priv_key       "/etc/config/certs/priv.crt"
 310     option priv_key_pwd   "PKCS#12 passphrase"
 311 \end{Verbatim}
 312
 313 \subparagraph{EAP-PEAP}
 314
 315 \begin{Verbatim}
 316 config wifi-iface
 317     option device         "ath0"
 318     option network        lan
 319     option ssid           OpenWrt
 320     option eap_type       peap
 321     option ca_cert        "/etc/config/certs/ca.crt"
 322     option auth           MSCHAPV2
 323     option identity       username
 324     option password       password
 325 \end{Verbatim}
 326
 327 \paragraph{Limitations:}
 328
 329 There are certain limitations when combining modes.
 330 Only the following mode combinations are supported:
 331
 332 \begin{itemize}
 333     \item \textbf{Broadcom}: \\
 334         \begin{itemize}
 335             \item 1x \texttt{sta}, 0-3x \texttt{ap}
 336             \item 1-4x \texttt{ap}
 337             \item 1x \texttt{adhoc}
 338             \item 1x \texttt{monitor}
 339         \end{itemize}
 340
 341         WDS links can only be used in pure AP mode and cannot use WEP (except when sharing the
 342         settings with the master interface, which is done automatically).
 343
 344     \item \textbf{Atheros}: \\
 345         \begin{itemize}
 346             \item 1x \texttt{sta}, 0-Nx \texttt{ap}
 347             \item 1-Nx \texttt{ap}
 348             \item 1x \texttt{adhoc}
 349         \end{itemize}
 350
 351         N is the maximum number of VAPs that the module allows, it defaults to 4, but can be
 352         changed by loading the module with the maxvaps=N parameter.
 353 \end{itemize}
 354
 355 \paragraph{Adding a new driver configuration}
 356
 357 Since we currently only support thread different wireless drivers : Broadcom, Atheros and mac80211,
 358 you might be interested in adding support for another driver like Ralink RT2x00,
 359 Texas Instruments ACX100/111.
 360
 361 The driver specific script should be placed in \texttt{/lib/wifi/<driver>.sh} and has to
 362 include several functions providing :
 363
 364 \begin{itemize}
 365         \item detection of the driver presence
 366         \item enabling/disabling the wifi interface(s)
 367         \item configuration reading and setting
 368         \item third-party programs calling (nas, supplicant)
 369 \end{itemize}
 370
 371 Each driver script should append the driver to a global DRIVERS variable :
 372
 373 \begin{Verbatim}
 374 append DRIVERS "driver name"
 375 \end{Verbatim}
 376
 377 \subparagraph{\texttt{scan\_<driver>}}
 378
 379 This function will parse the \texttt{/etc/config/wireless} and make sure there
 380 are no configuration incompatibilities, like enabling hidden SSIDS with ad-hoc mode
 381 for instance. This can be more complex if your driver supports a lof of configuration
 382 options. It does not change the state of the interface.
 383
 384 Example:
 385 \begin{Verbatim}
 386 scan_dummy() {
 387         local device="$1"
 388
 389         config_get vifs "$device" vifs
 390         for vif in $vifs; do
 391                 # check config consistency for wifi-iface sections
 392         done
 393         # check mode combination
 394 }
 395 \end{Verbatim}
 396
 397 \subparagraph{\texttt{enable\_<driver>}}
 398
 399 This function will bring up the wifi device and optionally create application specific
 400 configuration files, e.g. for the WPA authenticator or supplicant.
 401
 402 Example:
 403 \begin{Verbatim}
 404 enable_dummy() {
 405         local device="$1"
 406
 407         config_get vifs "$device" vifs
 408         for vif in $vifs; do
 409                 # bring up virtual interface belonging to
 410                 # the wifi-device "$device"
 411         done
 412 }
 413 \end{Verbatim}
 414
 415 \subparagraph{\texttt{disable\_<driver>}}
 416
 417 This function will bring down the wifi device and all its virtual interfaces (if supported).
 418
 419 Example:
 420 \begin{Verbatim}
 421 disable_dummy() {
 422         local device="$1"
 423
 424         # bring down virtual interfaces belonging to
 425         # "$device" regardless of whether they are
 426         # configured or not. Don't rely on the vifs
 427         # variable at this point
 428 }
 429 \end{Verbatim}
 430
 431 \subparagraph{\texttt{detect\_<driver>}}
 432
 433 This function looks for interfaces that are usable with the driver. Template config sections
 434 for new devices should be written to stdout. Must check for already existing config sections
 435 belonging to the interfaces before creating new templates.
 436
 437 Example:
 438 \begin{Verbatim}
 439 detect_dummy() {
 440         [ wifi-device = "$(config_get dummydev type)" ] && return 0
 441         cat <<EOF
 442 config wifi-device dummydev
 443         option type dummy
 444         # REMOVE THIS LINE TO ENABLE WIFI:
 445         option disabled 1
 446
 447 config wifi-iface
 448         option device dummydev
 449         option mode ap
 450         option ssid OpenWrt
 451 EOF
 452 }
 453 \end{Verbatim}