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, mesh, 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{mesh} \\
 188                 Mesh Point mode (802.11s)
 189
 190             \item \texttt{wds} \\
 191                 WDS point-to-point link
 192
 193         \end{itemize}
 194
 195     \item \texttt{ssid}
 196         Set the SSID to be used on the wifi device.
 197
 198     \item \texttt{bssid}
 199         Set the BSSID address to be used for wds to set the mac address of the other wds unit.
 200
 201     \item \texttt{txpower}
 202         (Deprecated, set in wifi-device) Set the transmission power to be used. The amount is specified in dBm.
 203
 204     \item \texttt{encryption} \\
 205         Encryption setting. Accepts the following values:
 206
 207         \begin{itemize}
 208             \item \texttt{none}
 209             \item \texttt{wep}
 210             \item \texttt{psk}, \texttt{psk2} \\
 211                 WPA(2) Pre-shared Key
 212
 213             \item \texttt{wpa}, \texttt{wpa2} \\
 214                 WPA(2) RADIUS
 215         \end{itemize}
 216
 217     \item \texttt{key, key1, key2, key3, key4} (wep, wpa and psk) \\
 218         WEP key, WPA key (PSK mode) or the RADIUS shared secret (WPA RADIUS mode)
 219
 220     \item \texttt{server} (wpa) \\
 221         The RADIUS server ip address
 222
 223     \item \texttt{port} (wpa) \\
 224         The RADIUS server port (defaults to 1812)
 225
 226     \item \texttt{hidden} \\
 227         0 broadcasts the ssid; 1 disables broadcasting of the ssid
 228
 229     \item \texttt{isolate} \\
 230         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.
 231         0 disables ap isolation (default); 1 enables ap isolation.
 232
 233 \end{itemize}
 234
 235 \paragraph{Mesh Point}
 236
 237 Mesh Point (802.11s) is only supported by some mac80211 drivers. It requires the iw package
 238 to be installed to setup mesh links. OpenWrt creates mshN mesh point interfaces.
 239
 240 \paragraph{Wireless Distribution System}
 241
 242 WDS is a non-standard mode which will be working between two Broadcom devices for instance
 243 but not between a Broadcom and Atheros device.
 244
 245 \subparagraph{Unencrypted WDS connections}
 246
 247 This configuration example shows you how to setup unencrypted WDS connections.
 248 We assume that the peer configured as below as the BSSID ca:fe:ba:be:00:01
 249 and the remote WDS endpoint ca:fe:ba:be:00:02 (option bssid field).
 250
 251 \begin{Verbatim}
 252 config wifi-device      "wl0"
 253     option type         "broadcom"
 254     option channel      "5"
 255
 256 config wifi-iface
 257     option device       "wl0"
 258     option network      lan
 259     option mode         "ap"
 260     option ssid         "OpenWrt"
 261     option hidden       "0"
 262     option encryption   "none"
 263
 264 config wifi-iface
 265     option device       "wl0"
 266     option network      lan
 267     option mode         wds
 268     option ssid         "OpenWrt WDS"
 269     option bssid        "ca:fe:ba:be:00:02"
 270 \end{Verbatim}
 271
 272 \subparagraph{Encrypted WDS connections}
 273
 274 It is also possible to encrypt WDS connections. \texttt{psk}, \texttt{psk2} and
 275 \texttt{psk+psk2} modes are supported. Configuration below is an example
 276 configuration using Pre-Shared-Keys with AES algorithm.
 277
 278 \begin{Verbatim}
 279 config wifi-device  wl0
 280     option type     broadcom
 281     option channel  5
 282
 283 config wifi-iface
 284     option device   "wl0"
 285     option network  lan
 286     option mode     ap
 287     option ssid     "OpenWrt"
 288     option encryption  psk2
 289     option key      "<key for clients>"
 290
 291 config wifi-iface
 292     option device   "wl0"
 293     option network  lan
 294     option mode     wds
 295     option bssid    ca:fe:ba:be:00:02
 296     option ssid     "OpenWrt WDS"
 297     option encryption   psk2
 298     option key      "<psk for WDS>"
 299 \end{Verbatim}
 300
 301 \paragraph{802.1x configurations}
 302
 303 OpenWrt supports both 802.1x client and Access Point
 304 configurations. 802.1x client is only working with
 305 Atheros or mac80211 drivers. Configuration only
 306 supports EAP types TLS, TTLS or PEAP.
 307
 308 \subparagraph{EAP-TLS}
 309
 310 \begin{Verbatim}
 311 config wifi-iface
 312     option device         "ath0"
 313     option network        lan
 314     option ssid           OpenWrt
 315     option eap_type       tls
 316     option ca_cert        "/etc/config/certs/ca.crt"
 317     option priv_key       "/etc/config/certs/priv.crt"
 318     option priv_key_pwd   "PKCS#12 passphrase"
 319 \end{Verbatim}
 320
 321 \subparagraph{EAP-PEAP}
 322
 323 \begin{Verbatim}
 324 config wifi-iface
 325     option device         "ath0"
 326     option network        lan
 327     option ssid           OpenWrt
 328     option eap_type       peap
 329     option ca_cert        "/etc/config/certs/ca.crt"
 330     option auth           MSCHAPV2
 331     option identity       username
 332     option password       password
 333 \end{Verbatim}
 334
 335 \paragraph{Limitations:}
 336
 337 There are certain limitations when combining modes.
 338 Only the following mode combinations are supported:
 339
 340 \begin{itemize}
 341     \item \textbf{Broadcom}: \\
 342         \begin{itemize}
 343             \item 1x \texttt{sta}, 0-3x \texttt{ap}
 344             \item 1-4x \texttt{ap}
 345             \item 1x \texttt{adhoc}
 346             \item 1x \texttt{monitor}
 347         \end{itemize}
 348
 349         WDS links can only be used in pure AP mode and cannot use WEP (except when sharing the
 350         settings with the master interface, which is done automatically).
 351
 352     \item \textbf{Atheros}: \\
 353         \begin{itemize}
 354             \item 1x \texttt{sta}, 0-Nx \texttt{ap}
 355             \item 1-Nx \texttt{ap}
 356             \item 1x \texttt{adhoc}
 357         \end{itemize}
 358
 359         N is the maximum number of VAPs that the module allows, it defaults to 4, but can be
 360         changed by loading the module with the maxvaps=N parameter.
 361 \end{itemize}
 362
 363 \paragraph{Adding a new driver configuration}
 364
 365 Since we currently only support thread different wireless drivers : Broadcom, Atheros and mac80211,
 366 you might be interested in adding support for another driver like Ralink RT2x00,
 367 Texas Instruments ACX100/111.
 368
 369 The driver specific script should be placed in \texttt{/lib/wifi/<driver>.sh} and has to
 370 include several functions providing :
 371
 372 \begin{itemize}
 373         \item detection of the driver presence
 374         \item enabling/disabling the wifi interface(s)
 375         \item configuration reading and setting
 376         \item third-party programs calling (nas, supplicant)
 377 \end{itemize}
 378
 379 Each driver script should append the driver to a global DRIVERS variable :
 380
 381 \begin{Verbatim}
 382 append DRIVERS "driver name"
 383 \end{Verbatim}
 384
 385 \subparagraph{\texttt{scan\_<driver>}}
 386
 387 This function will parse the \texttt{/etc/config/wireless} and make sure there
 388 are no configuration incompatibilities, like enabling hidden SSIDS with ad-hoc mode
 389 for instance. This can be more complex if your driver supports a lof of configuration
 390 options. It does not change the state of the interface.
 391
 392 Example:
 393 \begin{Verbatim}
 394 scan_dummy() {
 395         local device="$1"
 396
 397         config_get vifs "$device" vifs
 398         for vif in $vifs; do
 399                 # check config consistency for wifi-iface sections
 400         done
 401         # check mode combination
 402 }
 403 \end{Verbatim}
 404
 405 \subparagraph{\texttt{enable\_<driver>}}
 406
 407 This function will bring up the wifi device and optionally create application specific
 408 configuration files, e.g. for the WPA authenticator or supplicant.
 409
 410 Example:
 411 \begin{Verbatim}
 412 enable_dummy() {
 413         local device="$1"
 414
 415         config_get vifs "$device" vifs
 416         for vif in $vifs; do
 417                 # bring up virtual interface belonging to
 418                 # the wifi-device "$device"
 419         done
 420 }
 421 \end{Verbatim}
 422
 423 \subparagraph{\texttt{disable\_<driver>}}
 424
 425 This function will bring down the wifi device and all its virtual interfaces (if supported).
 426
 427 Example:
 428 \begin{Verbatim}
 429 disable_dummy() {
 430         local device="$1"
 431
 432         # bring down virtual interfaces belonging to
 433         # "$device" regardless of whether they are
 434         # configured or not. Don't rely on the vifs
 435         # variable at this point
 436 }
 437 \end{Verbatim}
 438
 439 \subparagraph{\texttt{detect\_<driver>}}
 440
 441 This function looks for interfaces that are usable with the driver. Template config sections
 442 for new devices should be written to stdout. Must check for already existing config sections
 443 belonging to the interfaces before creating new templates.
 444
 445 Example:
 446 \begin{Verbatim}
 447 detect_dummy() {
 448         [ wifi-device = "$(config_get dummydev type)" ] && return 0
 449         cat <<EOF
 450 config wifi-device dummydev
 451         option type dummy
 452         # REMOVE THIS LINE TO ENABLE WIFI:
 453         option disabled 1
 454
 455 config wifi-iface
 456         option device dummydev
 457         option mode ap
 458         option ssid OpenWrt
 459 EOF
 460 }
 461 \end{Verbatim}