linux查看wifi信号命令_linux无线网络命令

1、iwconfig

iwconfig是Linux Wireless Extensions(LWE)的用户层配置工具之一。LWE是Linux下对无线网络配置的工具，包括内核的支持、用户层配置工具和驱动接口的支持三部 分。目前很多无线网卡都支持LWE，而且主流的Linux发布版本，比如Redhat Linux、Ubuntu Linux都已经带了这个配置工具。

用法: iwconfig interface [essid {NN|on|off}]

[nwid {NN|on|off}]

[mode {managed|ad-hoc|...}

[freq N.NNNN[k|M|G]]

[channel N]

[ap {N|off|auto}]

[sens N]

[nick N]

[rate {N|auto|fixed}]

[rts {N|auto|fixed|off}]

[frag {N|auto|fixed|off}]

[enc {NNNN-NNNN|off}]

[power {period N|timeout N}]

[retry {limit N|lifetime N}]

[txpower N {mW|dBm}]

[commit]

说明：iwconfig是LWE最主要的工具，可以对无线网卡的大部分参数进行配置。

参数：

essid： 设置无线网卡的ESSID(Extension Service Set ID)。通过ESSID来区分不同的无线网络，正常情况下只有相同ESSID的无线站点才可以互相通讯，除非想监听无线网络。其后的参数为双引号括起的 ESSID字符串，或者是any/on/off，如果ESSID字符串中包含any/no/off，则需要在前面加"--"。

示例：

#iwconfig eth0 essid any 允许任何ESSID，也就是混杂模式

#iwconfig eth0 essid "My Network" 设置ESSID为"My Network"

#iwconfig eth0 essid -- "ANY" 设置ESSID为"ANY"

nwid: Network ID，只用于pre-802.11的无线网卡，802.11网卡利用ESSID和AP的MAC地址来替换nwid，现在基本上不用设置。

示例：

#iwconfig eth0 nwid AB34

#iwconfig eth0 nwid off

nick: Nickname，一些网卡需要设置该参数，但是802.11协议栈、MAC都没有用到该参数，一般也不用设置。

示例：

#iwconfig eth0 nickname "My Linux Node"

mode：设置无线网卡的工作模式，可以是

Ad-hoc：不带AP的点对点无线网络

Managed：通过多个AP组成的网络，无线设备可以在这个网络中漫游

Master：设置该无线网卡为一个AP

Repeater：设置为无线网络中继设备，可以转发网络包

Secondary：设置为备份的AP/Repeater

Monitor：监听模式

Auto：由无线网卡自动选择工作模式

示例：

#iwconfig eth0 mode Managed

#iwconfig eth0 mode Ad-Hoc

freq/channel： 设置无线网卡的工作频率或者频道，小于1000的参数被认为是频道，大于10000的参数被认为是频率。频率单位为Hz，可以在数字后面附带k, M, G来改变数量级，比如2.4G。频道从1开始。使用lwlist工具可以查看无线网卡支持的频率和频道。参数off/auto指示无线网络自动挑选频率。

注意：如果是Managed模式，AP会指示无线网卡的工作频率，因此该设置的参数会被忽略。Ad-hoc模式下只使用该设定的频率初始无线网络，如果加入已经存在的Ad-hoc网络则会忽略该设置的频率参数。

示例：

#iwconfig eth0 freq 2422000000

#iwconfig eth0 freq 2.422G

#iwconfig eth0 channel 3

#iwconfig eth0 channel auto

ap： 连接到指定的AP或者无线网络，后面的参数可以是AP的MAC地址，也可以是iwlist scan出来的标识符。如果是Ad-hoc，则连接到一个已经存在的Ad-hoc网络。使用off参数让无线网卡不改变当前已连接的AP下进入自动模式。 any/auto参数，无线网卡自动选择最好的AP。

注意：如果无线信号低到一定程度，无线网络会进入自动选择AP模式。

示例：

#iwconfig eth0 ap 00:60:1D:01:23:45

#iwconfig eth0 ap any

#iwconfig eth0 ap off

rate/bit： 如果无线网卡支持多速率，则可以通过该命令设置工作的速率。小于1000的参数由具体的无线网卡驱动定义，一般是传输速率的索引值，大于1000的为速 率，单位bps，可以在数字后面附带k, M, G来指定数量级。auto参数让无线网卡自动选择速率fixed参数让无线网卡不使用自动速率模式。

示例：

#iwconfig eth0 rate 11M

#iwconfig eth0 rate auto

#iwconfig eth0 rate 5.5M auto //自动选择5.5M以下的速率

txpower：如果无线网卡支持多发射功率设定，则使用该参数设定发射，单位为dBm，如果指定为W(毫瓦)，只转换公式为：

dBm=30+log(W)。参数on/off可以打开和关闭发射单元，auto和fixed指定无线是否自动选择发射功率。

示例：

#iwconfig eth0 txpower 15

#iwconfig eth0 txpower 30mW

#iwconfig eth0 txpower auto

#iwconfig eth0 txpower off

sens：设置接收灵敏度的下限，在该下限之下，无线网卡认为该无线网络信号太差，不同的网卡会采取不同的措施，一些现代的无线网卡会自动选择新的AP。正的参数为raw data，直接传给无线网卡驱动处理，一般认为是百分比。负值表示dBm值。

示例：

#iwconfig eth0 sens -80

#iwconfig eth0 sens 2

retry： 设置无线网卡的重传机制。limit ‘value’ 指定最大重传次数；lifetime ‘value’指定最长重试时间，单位为秒，可以附带m和u来指定单位为毫秒和微秒。如果无线网卡支持自动模式，则在limit和lifetime之前还 可以附加min和max来指定上下限值。

示例：

#iwconfig eth0 retry 16

#iwconfig eth0 retry lifetime 300m

#iwconfig eth0 retry min limit 8

rts：指定RTS/CTS握手方式，使用RTS/CTS握手会增加额外开销，但如果无线网络中有隐藏无线节点或者有很多无线节点时可以提高性能。

后面的参数指定一个使用该机制的最小包的大小，如果该值等于最大包大小，则相当于禁止使用该机制。可以使用auto/off/fixed

参数。

示例：

#iwconfig eth0 rts 250

#iwconfig eth0 rts off

frag：设置发送数据包的分片大小。设置分片会增加额外开销，但在噪声环境下可以提高数据包的到达率。一般情况下该参数小于最大包大小，有些支持Burst模式的无线网卡可以设置大于最大包大小的值来允许Burst模式。还可以使用auto/fixed/off参数。

示例：

#iwconfig eth0 frag 512

#iwconfig eth0 frag off

key/enc[ryption]：设置无线网卡使用的加密密钥，此处为设置WEP模式的加密key，如果要使用WPA，需要wpa_supplicant工具包。

密 钥参数可以是 XXXX-XXXX-XXXX-XXXX 或者 XXXXXXXX 格式的十六进制数值，也可以是s:xxxxxx的ASCII字符。如果在密钥参数之前加了[index]，则只是设置该索引值对应的密钥，并不改变当前的 密钥。直接指定[index]值可以设置当前使用哪一个密钥。指定on/off可以控制是否使用加密模式。open/restricted指定加密模式， 取决于不同的无线网卡，大多数无线网卡的open模式不使用加密且允许接收没有加密的数据包，restricted模式使用加密。可以使用多个key参 数，但只有最后一个生效。

WEP密钥可以是40bit，用10个十六进制数字或者5个ASCII字符表示，也可以是128bit，用26个十六进制数字或者13个ASCII字符表

示。

示例：

#iwconfig eth0 key 0123-4567-89

#iwconfig eth0 key [3] 0123-4567-89

#iwconfig eth0 key s:password [2]

#iwconfig eth0 key [2]

#iwconfig eth0 key open

#iwconfig eth0 key off

#iwconfig eth0 key restricted [3] 0123456789

#iwconfig eth0 key 01-23 key 45-67 [4] key [4]

power：设置无线网卡的电源管理模式。period ‘value’ 指定唤醒的周期，timeout ‘value’指定进入休眠的等待时间，这两个参数之前可以

加min和max修饰，这些值的单位为秒，可以附加m和u来指定毫秒和微秒。off/on参数指定是否允许电源管理，all/unicast/multicast

指定允许唤醒的数据包类型。

示例：

#iwconfig eth0 power period 2

#iwconfig eth0 power 500m unicast

#iwconfig eth0 power timeout 300u all

#iwconfig eth0 power off

#iwconfig eth0 power min period 2 power max period 4

commit：提交所有的参数修改给无线网卡驱动。有些无线网卡驱动会先缓存无线网卡参数修，使用这个命令来让无线网卡的参数修改生效。不过一般不需要使用该命令，因为无线网卡驱动最终都会是参数的修改生效，一般在debug时会用到。

-----------

iwlist eth1 scan 搜索无线网络:

显示搜到的网络(此处只显示一个)：

eth1 Scan completed :

Cell 01 - Address: 00:04:E2:E3:04:FC

ESSID:"ap_demo"

Mode:Managed

Frequency:2.437 GHz

Quality:0/0 Signal level=-61 dBm Noise level=-96 dBm

Encryption key:on

Bit Rate:1 Mb/s

Bit Rate:2 Mb/s

Bit Rate:5.5 Mb/s

Bit Rate:11 Mb/s

Bit Rate:6 Mb/s

Bit Rate:9 Mb/s

Bit Rate:12 Mb/s

Bit Rate:18 Mb/s

Bit Rate:24 Mb/s

Bit Rate:36 Mb/s

Bit Rate:48 Mb/s

Bit Rate:54 Mb/s

Cell 02 ……

---------------

设置板子的channel

iwlist eth1 channel 11

--------------

设置模式：

iwconfig eth1 mode managed

通过MAC 设置AP：

iwconfig eth1 ap 00:0A:EB:CA:79:B0

连接到WEP on 的AP：

iwconfig eth1 key s:12345 等效于 iwconfig eth1 enc 3132333435(12345的hex值) (为什么AP64bit的口令是40bit呢)

iwconfig eth1 key on

iwconfig eth1 essid sychip_demo

断开WEP：

iwconfig eth1 enc off

查看IP：

ifconfig eth1

设置IP：

ifconfig eth1 10.3.1.74

把IP: 129.158.215.204 , netmask: 255.255.255.0分配给rh0，

# ifconfig rh0 129.158.215.204 netmask 255.255.255.0

获取IP；

ifconfig eth1 dhcp start (从eth1走，不需要ip即可dhcp)

udhcpc -i eth1

udhcpc --help

路由处理：

若要删除以 10. 起始的 IP 路由表中的所有路由，请键入：

route delete 10.*

route del default

route add -net 10.3.0.0 netmask 255.255.0.0 eth1 (eth1获得IP之前，使用此命令显示：No such device)

iwconfig(8) - Linux man page

Name iwconfig - configure a wireless network interface

Synopsis

iwconfig [

interface

]

iwconfig

interface

[essid

X

] [nwid

N

] [mode

M

] [freq

F

]

[channel

C

]

[sens

S

]

[ap

A

]

[nick

NN ]

[rate

R

] [rts

RT

] [frag

FT

] [txpower

T

]

[enc

E

] [key

K

] [power

P

] [retry

R

]

[commit]

iwconfig --help

iwconfig --version

Description

Iwconfig is similar to

Iwconfig may also be used to display those parameters, and the wireless statistics (extracted from

/proc/net/wireless).

All these parameters and statistics are device dependent. Each driver will provide only some of them depending on hardware support, and the range of values may change. Please refer to the man page of each device for details.

Parameters

essid

Set the ESSID (or Network Name - in some products it may also be called Domain ID). The ESSID is used to identify cells which are part of the same virtual network.

As opposed to the AP Address or NWID which define a single cell, the ESSID defines a group of cells connected via repeaters or infrastructure, where the user may roam transparently.

With some cards, you may disable the ESSID checking (ESSID promiscuous) with

off or

any (and

on to reenable it).

If the ESSID of your network is one of the special keywords (

off,

on or

any), you should use

-- to escape it.

Examples :

iwconfig eth0 essid any

iwconfig eth0 essid "My Network""

iwconfig eth0 essid -- "ANY""

nwid/

domain

Set the Network ID (in some products it may also be called Domain ID). As all adjacent wireless networks share the same medium, this parameter is used to differenciate them (create logical colocated networks) and identify nodes belonging to the same cell.

This parameter is only used for pre-802.11 hardware, the 802.11 protocol uses the ESSID and AP Address for this function.

With some cards, you may disable the Network ID checking (NWID promiscuous) with

off (and

on to reenable it).

Examples :

iwconfig eth0 nwid AB34

iwconfig eth0 nwid off

nick[name]

Set the nickname, or the station name. Some 802.11 products do define it, but this is not used as far as the protocols (MAC, IP, TCP) are concerned and completely useless as far as configuration goes. Only some wireless diagnostic tools may use it.

Example :

iwconfig eth0 nickname "My Linux Node""

mode

Set the operating mode of the device, which depends on the network topology. The mode can be

Ad-Hoc (network composed of only one cell and without Access Point),

Managed (node connects to a network composed of many Access Points, with roaming),

Master (the node is the synchronisation master or acts as an Access Point),

Repeater (the node forwards packets between other wireless nodes),

Secondary (the node acts as a backup master/repeater),

Monitor (the node is not associated with any cell and passively monitor all packets on the frequency) or

Auto.

Example :

iwconfig eth0 mode Managed

iwconfig eth0 mode Ad-Hoc

freq/

channel

Set the operating frequency or channel in the device. A value below 1000 indicates a channel number, a value greater than 1000 is a frequency in Hz. You may append the suffix k, M or G to the value (for example, "2.46G" for 2.46 GHz frequency), or add enough '0'.

Channels are usually numbered starting at 1, and you may use

off or

auto to let the card pick up the best channel (when supported).

Examples :

iwconfig eth0 freq 2422000000

iwconfig eth0 freq 2.422G

iwconfig eth0 channel 3

iwconfig eth0 channel auto

ap

Force the card to register to the Access Point given by the address, if it is possible. This address is the cell identity of the Access Point, as reported by wireless scanning, which may be different from its network MAC address. If the wireless link is point to point, set the address of the other end of the link. If the link is ad-hoc, set the cell identity of the ad-hoc network.

When the quality of the connection goes too low, the driver may revert back to automatic mode (the card selects the best Access Point in range).

You may also use

off to re-enable automatic mode without changing the current Access Point, or you may use

any or

auto to force the card to reassociate with the currently best Access Point.

Example :

iwconfig eth0 ap 00:60:1D:01:23:45

iwconfig eth0 ap any

iwconfig eth0 ap off

rate/

bit[rate]

For cards supporting multiple bit rates, set the bit-rate in b/s. The bit-rate is the speed at which bits are transmitted over the medium, the user speed of the link is lower due to medium sharing and various overhead.

You may append the suffix k, M or G to the value (decimal multiplier : 10^3, 10^6 and 10^9 b/s), or add enough '0'. Values below 1000 are card specific, usually an index in the bit-rate list. Use

auto to select automatic bit-rate mode (fallback to lower rate on noisy channels), which is the default for most cards, and

fixed to revert back to fixed setting. If you specify a bit-rate value and append

auto, the driver will use all bit-rates lower and equal than this value.

Examples :

iwconfig eth0 rate 11M

iwconfig eth0 rate auto

iwconfig eth0 rate 5.5M auto

txpower

For cards supporting multiple transmit powers, sets the transmit power in dBm. If

W is the power in Watt, the power in dBm is

P = 30 +10.log(W). If the value is postfixed by

mW, it will be automatically converted to dBm.

In addition,

on and

off enable and disable the radio, and

auto and

fixed enable and disable power control (if those features are available).

Examples :

iwconfig eth0 txpower 15

iwconfig eth0 txpower 30mW

iwconfig eth0 txpower auto

iwconfig eth0 txpower off

sens

Set the sensitivity threshold. This define how sensitive is the card to poor operating conditions (low signal, interference). Positive values are assumed to be the raw value used by the hardware or a percentage, negative values are assumed to be dBm. Depending on the hardware implementation, this parameter may control various functions.

On modern cards, this parameter usually control handover/roaming threshold, the lowest signal level for which the hardware remains associated with the current Access Point. When the signal level goes below this threshold the card starts looking for a new/better Access Point. Some cards may use the number of missed beacons to trigger this. For high density of Access Points, a higher threshold make sure the card is always associated with the best AP, for low density of APs, a lower threshold minimise the number of failed handoffs.

On more ancient card this parameter usually controls the defer threshold, the lowest signal level for which the hardware considers the channel busy. Signal levels above this threshold make the hardware inhibits its own transmission whereas signals weaker than this are ignored and the hardware is free to transmit. This is usually strongly linked to the receive threshold, the lowest signal level for which the hardware attempts packet reception. Proper setting of these thresholds prevent the card to waste time on background noise while still receiving weak transmissions. Modern designs seems to control those thresholds automatically.

Example :

iwconfig eth0 sens -80

iwconfig eth0 sens 2

retry

Most cards have MAC retransmissions, and some allow to set the behaviour of the retry mechanism.

To set the maximum number of retries, enter

limit 'value'. This is an absolute value (without unit). To set the maximum length of time the MAC should retry, enter

lifetime 'value'. By defaults, this value in in seconds, append the suffix m or u to specify values in milliseconds or microseconds.

You can also add the

min and

max modifiers. If the card supports automatic mode, they define the bounds of the limit or lifetime. Some other cards define different values depending on packet size, for example in 802.11

min limit is the short retry limit (non RTS/CTS packets).

Examples :

iwconfig eth0 retry 16

iwconfig eth0 retry lifetime 300m

iwconfig eth0 retry min limit 8

rts[_threshold]

RTS/CTS adds a handshake before each packet transmission to make sure that the channel is clear. This adds overhead, but increases performance in case of hidden nodes or a large number of active nodes. This parameter sets the size of the smallest packet for which the node sends RTS ; a value equal to the maximum packet size disables the mechanism. You may also set this parameter to

auto,

fixed or

off.

Examples :

iwconfig eth0 rts 250

iwconfig eth0 rts off

frag[mentation_threshold]

Fragmentation allows to split an IP packet in a burst of smaller fragments transmitted on the medium. In most cases this adds overhead, but in a very noisy environment this reduces the error penalty and allow packets to get through interference bursts. This parameter sets the maximum fragment size which is always lower than the maximum packet size.

This parameter may also control Frame Bursting available on some cards, the ability to send multiple IP packets together. This mechanism would be enabled if the fragment size is larger than the maximum packet size.

You may also set this parameter to

auto,

fixed or

off.

Examples :

iwconfig eth0 frag 512

iwconfig eth0 frag off

key/

enc[ryption]

Used to manipulate encryption or scrambling keys and security mode.

To set the current encryption key, just enter the key in hex digits as

XXXX-XXXX-XXXX-XXXX or

XXXXXXXX. To set a key other than the current key, prepend or append

[index] to the key itself (this won't change which is the active key). You can also enter the key as an ASCII string by using the

s: prefix. Passphrase is currently not supported.

To change which key is the currently active key, just enter

[index] (without entering any key value).

off and

on disable and reenable encryption.

The security mode may be

open or

restricted, and its meaning depends on the card used. With most cards, in

open mode no authentication is used and the card may also accept non-encrypted sessions, whereas in

restricted mode only encrypted sessions are accepted and the card will use authentication if available.

If you need to set multiple keys, or set a key and change the active key, you need to use multiple

key directives. Arguments can be put in any order, the last one will take precedence.

Examples :

iwconfig eth0 key 0123-4567-89

iwconfig eth0 key [3] 0123-4567-89

iwconfig eth0 key s:password [2]

iwconfig eth0 key [2]

iwconfig eth0 key open

iwconfig eth0 key off

iwconfig eth0 key restricted [3] 0123456789

iwconfig eth0 key 01-23 key 45-67 [4] key [4]

power

Used to manipulate power management scheme parameters and mode.

To set the period between wake ups, enter

period 'value'. To set the timeout before going back to sleep, enter

timeout 'value'. You can also add the

min and

max modifiers. By default, those values are in seconds, append the suffix m or u to specify values in milliseconds or microseconds. Sometimes, those values are without units (number of beacon periods, dwell or similar).

off and

on disable and reenable power management. Finally, you may set the power management mode to

all (receive all packets),

unicast (receive unicast packets only, discard multicast and broadcast) and

multicast (receive multicast and broadcast only, discard unicast packets).

Examples :

iwconfig eth0 power period 2

iwconfig eth0 power 500m unicast

iwconfig eth0 power timeout 300u all

iwconfig eth0 power off

iwconfig eth0 power min period 2 power max period 4

commit

Some cards may not apply changes done through Wireless Extensions immediately (they may wait to aggregate the changes or apply it only when the card is brought up via ifconfig). This command (when available) forces the card to apply all pending changes.

This is normally not needed, because the card will eventually apply the changes, but can be useful for debugging.

Display For each device which supports wireless extensions,

iwconfig will display the name of the

MAC protocol used (name of device for proprietary protocols), the

ESSID (Network Name), the

NWID, the

frequency (or channel), the

sensitivity, the

mode of operation, the

Access Point address, the

bit-rate, the

RTS threshold, the

fragmentation threshold, the

encryption key and the

power management settings (depending on availability).

The parameters displayed have the same meaning and values as the parameters you can set, please refer to the previous part for a detailed explanation of them.

Some parameters are only displayed in short/abbreviated form (such as encryption). You may use =', it means that the parameter is fixed and forced to that value, if it is prefixed by ':', the parameter is in automatic mode and the current value is shown (and may change).

Access Point/

Cell

An address equal to 00:00:00:00:00:00 means that the card failed to associate with an Access Point (most likely a configuration issue). The

Access Point parameter will be shown as

Cell in ad-hoc mode (for obvious reasons), but otherwise works the same.

If /proc/net/wireless exists, iwconfig will also display its content. Note that those values will depend on the driver and the hardware specifics, so you need to refer to your driver documentation for proper interpretation of those values.

Link quality

Overall quality of the link. May be based on the level of contention or interference, the bit or frame error rate, how good the received signal is, some timing synchronisation, or other hardware metric. This is an aggregate value, and depends totally on the driver and hardware.

Signal level

Received signal strength (RSSI - how strong the received signal is). May be arbitrary units or dBm,

iwconfig uses driver meta information to interpret the raw value given by

/proc/net/wireless and display the proper unit or maximum value (using 8 bit arithmetic). In

Ad-Hoc mode, this may be undefined and you should use

iwspy.

Noise level

Background noise level (when no packet is transmitted). Similar comments as for

Signal level.

Rx invalid nwid

Number of packets received with a different NWID or ESSID. Used to detect configuration problems or adjacent network existence (on the same frequency).

Rx invalid crypt

Number of packets that the hardware was unable to decrypt. This can be used to detect invalid encryption settings.

Rx invalid frag

Number of packets for which the hardware was not able to properly re-assemble the link layer fragments (most likely one was missing).

Tx excessive retries

Number of packets that the hardware failed to deliver. Most MAC protocols will retry the packet a number of times before giving up.

Invalid misc

Other packets lost in relation with specific wireless operations.

Missed beacon

Number of periodic beacons from the Cell or the Access Point we have missed. Beacons are sent at regular intervals to maintain the cell coordination, failure to receive them usually indicates that the card is out of range.