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 agmode       "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 agmode     11b, 11g, 11a, 11bg (atheros only)
 103
 104 config wifi-iface
 105     option network  the interface you want wifi to bridge with
 106     option device   wifi0, wifi1, wifi2, wifiN
 107     option mode     ap, sta, adhoc, monitor, or wds
 108     option ssid     ssid name
 109     option bssid    bssid address
 110     option encryption none, wep, psk, psk2, wpa, wpa2
 111     option key      encryption key
 112     option key1     key 1
 113     option key2     key 2
 114     option key3     key 3
 115     option key4     key 4
 116     option server   ip address
 117     option port     port
 118     option hidden   0,1
 119     option isolate  0,1
 120 \end{Verbatim}
 121
 122 \paragraph{Options for the \texttt{wifi-device}:}
 123
 124 \begin{itemize}
 125     \item \texttt{type} \\
 126         The driver to use for this interface.
 127
 128     \item \texttt{country} \\
 129         The country code used to determine the regulatory settings.
 130
 131     \item \texttt{channel} \\
 132         The wifi channel (e.g. 1-14, depending on your country setting).
 133
 134     \item \texttt{maxassoc} \\
 135         Optional: Maximum number of associated clients. This feature is supported only on the broadcom chipset.
 136
 137     \item \texttt{distance} \\
 138         Optional: Distance between the ap and the furthest client in meters. This feature is supported only on the atheros chipset.
 139
 140         \item \texttt{mode} \\
 141                 The frequency band (\texttt{b}, \texttt{g}, \texttt{bg}, \texttt{a}). This feature is only supported on the atheros chipset.
 142
 143
 144 \end{itemize}
 145
 146 \paragraph{Options for the \texttt{wifi-iface}:}
 147
 148 \begin{itemize}
 149     \item \texttt{network} \\
 150         Selects the interface section from \texttt{/etc/config/network} to be
 151         used with this interface
 152
 153     \item \texttt{device} \\
 154         Set the wifi device name.
 155
 156     \item \texttt{mode} \\
 157         Operating mode:
 158
 159         \begin{itemize}
 160             \item \texttt{ap} \\
 161                 Access point mode
 162
 163             \item \texttt{sta} \\
 164                 Client mode
 165
 166             \item \texttt{adhoc} \\
 167                 Ad-Hoc mode
 168
 169             \item \texttt{monitor} \\
 170                 Monitor mode
 171
 172             \item \texttt{wds} \\
 173                 WDS point-to-point link
 174
 175         \end{itemize}
 176
 177     \item \texttt{ssid}
 178         Set the SSID to be used on the wifi device.
 179
 180     \item \texttt{bssid}
 181         Set the BSSID address to be used for wds to set the mac address of the other wds unit.
 182
 183     \item \texttt{encryption} \\
 184         Encryption setting. Accepts the following values:
 185
 186         \begin{itemize}
 187             \item \texttt{none}
 188             \item \texttt{wep}
 189             \item \texttt{psk}, \texttt{psk2} \\
 190                 WPA(2) Pre-shared Key
 191
 192             \item \texttt{wpa}, \texttt{wpa2} \\
 193                 WPA(2) RADIUS
 194         \end{itemize}
 195
 196     \item \texttt{key, key1, key2, key3, key4} (wep, wpa and psk) \\
 197         WEP key, WPA key (PSK mode) or the RADIUS shared secret (WPA RADIUS mode)
 198
 199     \item \texttt{server} (wpa) \\
 200         The RADIUS server ip address
 201
 202     \item \texttt{port} (wpa) \\
 203         The RADIUS server port (defaults to 1812)
 204
 205     \item \texttt{hidden} \\
 206         0 broadcasts the ssid; 1 disables broadcasting of the ssid
 207
 208     \item \texttt{isolate} \\
 209         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.
 210         0 disables ap isolation (default); 1 enables ap isolation.
 211
 212 \end{itemize}
 213
 214
 215 \paragraph{Limitations:}
 216
 217 There are certain limitations when combining modes.
 218 Only the following mode combinations are supported:
 219
 220 \begin{itemize}
 221     \item \textbf{Broadcom}: \\
 222         \begin{itemize}
 223             \item 1x \texttt{sta}, 0-3x \texttt{ap}
 224             \item 1-4x \texttt{ap}
 225             \item 1x \texttt{adhoc}
 226             \item 1x \texttt{monitor}
 227         \end{itemize}
 228
 229         WDS links can only be used in pure AP mode and cannot use WEP (except when sharing the
 230         settings with the master interface, which is done automatically).
 231
 232     \item \textbf{Atheros}: \\
 233         \begin{itemize}
 234             \item 1x \texttt{sta}, 0-Nx \texttt{ap}
 235             \item 1-Nx \texttt{ap}
 236             \item 1x \texttt{adhoc}
 237         \end{itemize}
 238
 239         N is the maximum number of VAPs that the module allows, it defaults to 4, but can be
 240         changed by loading the module with the maxvaps=N parameter.
 241 \end{itemize}
 242
 243 \paragraph{Adding a new driver configuration}
 244
 245 Since we currently only support two different wireless drivers : Broadcom and Atheros,
 246 you might be interested in adding support for another driver like Ralink RT2x00,
 247 Texas Instruments ACX100/111.
 248
 249 The driver specific script should be placed in \texttt{/lib/wifi/<driver>.sh} and has to
 250 include several functions providing :
 251
 252 \begin{itemize}
 253         \item detection of the driver presence
 254         \item enabling/disabling the wifi interface(s)
 255         \item configuration reading and setting
 256         \item third-party programs calling (nas, supplicant)
 257 \end{itemize}
 258
 259 Each driver script should append the driver to a global DRIVERS variable :
 260
 261 \begin{Verbatim}
 262 append DRIVERS "driver name"
 263 \end{Verbatim}
 264
 265 \subparagraph{\texttt{scan\_<driver>}}
 266
 267 This function will parse the \texttt{/etc/config/wireless} and make sure there
 268 are no configuration incompatibilities, like enabling hidden SSIDS with ad-hoc mode
 269 for instance. This can be more complex if your driver supports a lof of configuration
 270 options. It does not change the state of the interface.
 271
 272 Example:
 273 \begin{Verbatim}
 274 scan_dummy() {
 275         local device="$1"
 276
 277         config_get vifs "$device" vifs
 278         for vif in $vifs; do
 279                 # check config consistency for wifi-iface sections
 280         done
 281         # check mode combination
 282 }
 283 \end{Verbatim}
 284
 285 \subparagraph{\texttt{enable\_<driver>}}
 286
 287 This function will bring up the wifi device and optionally create application specific
 288 configuration files, e.g. for the WPA authenticator or supplicant.
 289
 290 Example:
 291 \begin{Verbatim}
 292 enable_dummy() {
 293         local device="$1"
 294
 295         config_get vifs "$device" vifs
 296         for vif in $vifs; do
 297                 # bring up virtual interface belonging to
 298                 # the wifi-device "$device"
 299         done
 300 }
 301 \end{Verbatim}
 302
 303 \subparagraph{\texttt{disable\_<driver>}}
 304
 305 This function will bring down the wifi device and all its virtual interfaces (if supported).
 306
 307 Example:
 308 \begin{Verbatim}
 309 disable_dummy() {
 310         local device="$1"
 311
 312         # bring down virtual interfaces belonging to
 313         # "$device" regardless of whether they are
 314         # configured or not. Don't rely on the vifs
 315         # variable at this point
 316 }
 317 \end{Verbatim}
 318
 319 \subparagraph{\texttt{detect\_<driver>}}
 320
 321 This function looks for interfaces that are usable with the driver. Template config sections
 322 for new devices should be written to stdout. Must check for already existing config sections
 323 belonging to the interfaces before creating new templates.
 324
 325 Example:
 326 \begin{Verbatim}
 327 detect_dummy() {
 328         [ wifi-device = "$(config_get dummydev type)" ] && return 0
 329         cat <<EOF
 330 config wifi-device dummydev
 331         option type dummy
 332         # REMOVE THIS LINE TO ENABLE WIFI:
 333         option disabled 1
 334
 335 config wifi-iface
 336         option device dummydev
 337         option mode ap
 338         option ssid OpenWrt
 339 EOF
 340 }
 341 \end{Verbatim}