Wireless Troubleshoot

8/9/2019 Wireless Troubleshoot

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WifiDocsWirelessTroubleShootingGuide

WifiDocs/WiFiTroubleshootingshould be merged into thisdocument.

1. Before using this

guide

Open System > Preferences > NetworkConfiguration - on Ubuntu 8.04 andlater this should be System >

Administration > Network. If you cansee a "Wireless Connection" entryunder the Connections tab, then you

may have a working driver alreadyinstalled and simply need to activatethe card. Select the entry and click onthe "Properties" button to the right.Check "Enable this connection" and fillin the appropriate information below(SSID, network name, passcode, andconnection settings). When finished,click OK and wait for the system toactivate your card. If this does notproduce a working connection, make

sure you have entered all settingscorrectly, then consult the remainder ofthis guide to track down your problem(s).

2. Purpose

This guide can serve as a checklist for troubleshooting your wireless networkconnections. While it may not solve all your problems, it can hopefully steer you inthe right direction.

Style Cleanup Required: This article does not follow the style standards inthe Wiki Guide. More info...

Contents

1. Before using this guide2. Purpose3. Overview

1. Steps2. Config files3. Connected but no internet

4. Commands4. Troubleshooting Steps1. Check Device2. Device Drivers3. Router Connection4. ip assignment5. Connected but no internet

5. Config Files6. Connection Established, Problems

Persist1. Dropped Connections2. Connected, Issues with

Certain Websites

3. Incorrect Driver Loads atBoot

7. Commands1. lshw2. lspci3. lsusb4. lsmod5. modprobe6. iwconfig7. ifconfig8. iwlist9. dhclient

10. ping11. Links

Page 1 of 22WifiDocs/WirelessTroubleShootingGuide - Community Ubuntu Documentation

20.Nov.09https://help.ubuntu.com/community/WifiDocs/WirelessTroubleShootingGuide?action...


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3. Overview

3.1. Steps

The basic structure

Check for Device Recognition

Check for driver

Check for router connection

Check for ip address assignment

Connected but no internet

This structure is setup in a specific order. Do not move on until you geteverything resolved in the current step. For example, step 3 is routerassociation. You can not move on to the next step of ip assignment until youget router association. If you can't get past a step, look for more help in thatspecific area. Once it's resolved, move onto the next step.

3.2. Config files

Any config file used in wireless will be listed with notes about the particularfile

3.3. Connected but no internet

This section will be devoted to those who have a working wirelessconnection but other problems occur such as dropped signal. This is afragmented work in progress currently.

3.4. Commands

Reading through the commands section is not necessary for this guide, butcould prove useful.

The first section contains the commands associated with troubleshootingwireless. Details about the command and some basics of what it does will begiven. When going through the steps, anywhere a command is given it willlink to the command section.

With each command will be an example with key points noted. For more information on each command check the manual.

man

Where a word appears inside . you need to input a value to complete thecommand. Do not include the symbols in your command.

eg Where you see you need to replace this with your device's




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logical name (could be ath0; wlan0; eth1; etc...)

To find the device's logical name, run:

sudo iwconfig

4. Troubleshooting Steps

4.1. Check Device

Commands we'll be using in this section: lshw lspci lsusb

4.1.1. PnP

Most devices are plug and play but it is worth checking.

plug and Play is a term used in the computer field to describe a computer'sability to have new device, normally peripherals, added without having toreconfigure or restart the computer. It is not a term stating the device will work asdescribed immediately. A driver has to be installed so the os can communicatewith the device

1. To check if device is recognized use the lshw command. If device shows up

then you can check off step I

4.1.2. Non-recognized Card

Some devices are not recognized by the OS upon insertion. [Needsexpansion.]

1. If card doesn't show up immediately try these steps:

Run the following command.Hopefully you'll get some output about thedevice.

sudo pccardctl ident

Socket 0:

product info: "Atheros Communications, Inc.", "AR5001-

0000-0000", "Wireless LAN Reference Card", "00"

manfid: 0x0271, 0x0012




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function: 6 (network)

If you get no output then the memory on the card cannot be read. Now

we need to open a configuration file and add this information to it:

gksudo gedit /etc/pcmcia/config.opts

the information you add should look like this, with your own datasubstituted.

card ""Atheros Communications, Inc.", "AR5001-0000-0000", "Wireless

0000", "Wireless LAN"

manfid 0x0271, 0x0012

function: 6 (network)

bind "ath_pci"

After making this change run this command:

sudo kill -HUP `cat /var/run/cardmgr.pid`

Now run lshw to see if the card is recognized and loaded properly.

Most cards requiring this step will be older devices. You should not have to dothis with any cards made in the past few years, but there can be exceptions.

Notice the bind line which states what driver should be allocated to the device.You will need to find what driver your device uses. More on that in the next step.

4.1.2.1. Problem with bridge in PCI bus line

On several, especially new systems the Yenta bridge is not on the root PCIbridge, but behind a PCI-to-PCI bridge. On some x86 or x86_64 systems,these bridges aren't corrreclty set up by the BIOS, which may cause CardBusand even PCMCIA devices not to show up in lspci or in pccardctl identcorrectly. If you suspect that this may be the cause, issue this command:

lspci -v | grep subordinate

Its result may be like this:

Bus: primary=00, secondary=02, subordinate=04, sec-latency=6




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latency=64

Bus: primary=02, secondary=03, subordinate=06, sec-

latency=176

Bus: primary=02, secondary=07, subordinate=0a, sec-

latency=176

Let's decode the first line: bus 0 (primary) is bridged to busses 2(secondary) to 4 (subordinate) by a bridge. The second and the thirdline state that bus 2 is bridged to busses 3-6, and 7-10. However, theCPU (which itself is connected to bus 0 through the root bridge) needsto be able to access all these busses. If you try to walk the tree to bus 7,for example, you see that the CPU can't get there, as bus 0 is onlybridged to busses 2 to 4.

If this is the case, or you find a message stating "try pci=assign-busses" inthe dmesg log, append the following to the kernel boot line:

pci=assign-busses

4.1.3. System locks upon card insertion

When a card is first inserted, the system attempts to read the card's memory.This can sometimes cause your system to lock-up. Try this to see if it helps:

1) Open the file /etc/pcmcia/config.opts

gksudo gedit /etc/pcmcia/config.opts

2) Find the following section:

include memory 0xc0000-0xfffff

include memory 0xa0000000-0xa0ffffff

include memory 0x60000000-0x60ffffff

3) Change it to look like this:

include memory 0xd0000-0xdffff

include memory 0xc0000-0xcffff

include memory 0xc8000-0xcffff

include memory 0xd8000-0xdffff

4.2. Device Drivers

Commands we'll be using in this section: lshw lsmod modprobe




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First you should check if a driver automatically loaded. (Your device may besupported in Ubuntu with a native driver.) Use the lshw command. As explainedunder lshw, if there is a line saying "configuration: ...driver=..." in the description

of the wireless card, this indicates the driver is OK

4.2.1. Native Linux Drivers

For Atheros cards, see WifiDocs/Driver/Atheros.

Linux wireless devices.

Devices using the ralink chipset are listed with the rt2x00 driver. thert2x00 driver only works for kernels 2.6.13 or greater. For a kernel older then this

you need to use rt2500 for pci devices or rt2570 for usb devices

4.2.2. ndiswrapper for non supported cards

Not all cards/devices have a linux driver. If you find your card is not supportedyou will have to look at an app called ndiswrapper.

You can check here to see if your card is supported by ndiswrapper.

full information on ndiswrapper kept on this page including troubleshootinghelp specific to ndiswrapper.

Sometimes ndiswrapper is used prematurely. There may be a native driver thatcomes with Ubuntu which is taking the primary driver position and conflictingwith ndiswrapper. In such cases, if the native driver does not work properly withyour card you want to use ndiswrapper, you can blacklist the native driver, byadding a file to/etc/modprobe.d/. The file name must begin with the blacklistprefix. In this file you can blacklist modules (so that they will not be loaded uponcard chipset recognition) with the following syntax :

blacklist modulename

For example, if you own a D-Link DWL-G520+ card which uses the ACX111chipset, and you plan to use the ndiswrapper module, you have to blacklist the acxmodule, by creating the file/etc/modprobe.d/blacklist-acx with a single line insidewhich states :

blacklist acx

4.2.3. Check driver




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If you ran lshw and saw a driver bound to the device then let's test to makesure it's communicating to the kernel.

1. run the command lsmod to see if driver is loaded. (look for the driver

name that was listed in the output of lshw, "configuration" line). If youdid not see the driver module in the list then use the modprobecommand to load it.

2. run the command iwconfig. If you see output like in the example inthe command section then the driver is at least identifying the deviceas a wireless device to the kernel.

a. Opening networking in system>administration> and seeing thedevice in the list is how to identify through gui if driver is atleast communicating to the kernel at a basic level.

3. run the command iwlist to scan for a router. If an access point isidentified this is a second identifier which shows the driver ascommunicating and shows that it's probably working as it cancomplete a wireless interface task. (note not all cards support scanningso this may not work for you)

4.2.4. Multiple drivers loaded

For some cards (e.g., SMC2632W v1.02), an additional set of drivers isincorrectly loaded, effectively disabling wireless networking by generatingtwo apparent wifi cards where there should only be one. Typically, you'll seeentries for both eth1 and wlan0_rename after running the iwconfig

command, with your communication speed divided evenly between them.One of those drivers should not be loaded, and should be blacklisted. To doso, edit /etc/modprobe.d/blacklist and add the following lines:

blacklist

blacklist _cs

where is, for example, "hostap" (the "hostap" driverapparently causes problems for several cards). Then save, reboot, and checkyour connection with iwconfig.

4.2.5. Driver looks ok, device disabled

Newer laptops come with features to disable the wireless radio to savebattery when not in use. Usually this is switched by a FN+Fx key combo orspecific button for the purpose. It is possible driver and everything is ok butthe wireless device is in the disabled state and can't be used. Using thedesignated key(s) in linux sometimes does not work.

Usually this is apparent by running the lshw command you see *-

network:1 DISABLED or wireless=radio off, or if you run the

iwconfig command you see eth1 NOT READY!. So how do you




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rectify this? It varies so much the exact solution can't be put here in thisdocument for all the different models. So...

Look at the LaptopTestingTeam page on the team wiki to see if your laptop

is listed with any information. Do a google search using terms such as manufacture, model, linux, wireless,

enable, button, radio....etc. When searching and finding similar pages thatdon't help, use words that are used in those pages to help you search.

Go to the ubuntu forums and ask, maybe someone else has the same laptopand knows the work around.

4.3. Router Connection

Commands we'll be using in this section: iwconfig

With the driver loaded go to the panel System>Administration>Networking.Highlight your device and click properties. Enter your networking info, clickok then try to activate.

1. You should see an applet in the panel showing a connection. (Youmay need to set properties to show correct interface)

2. You can check if you're associated to router by running the commandiwconfig.

You can also connect to the router via the command line using the commandiwconfig. The syntax looks like this.

sudo iwconfig essid ap key

key mode commit

note: not all these may be used, check theman page for more informatin

If you can not connect to the router then try these.1. Change to an open signal (instead of wep or wpa). This may be an

unattractive option but it's a short term one to make sure the card andap can connect. Once you've verified this then you can add encryptionback in.

a. When using wep more people seem to have success using anopen key instead of shared and a hexadecimal method instead ofascii. But there should be no reason any setting shouldn't work.Try the settings you want and consider adjusting if you haveproblems.

b. To get wpa working you will need to install the wpasupplicantfrom the repositories. There are instructions for various driverson using wpa. See notes on wpa below.

2. Download a scanner such as network manager, gtk wifi, or wifi radar.of course this is not an option if you can not connect to the internet without wireless

3. Try booting with kernel option pci=noacpi or acpi=off as acpi




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sometimes conflicts with network devices. The second option willaffect power management.

4. Check for firmware update on the router and update it if there is newer

firmware available.5. Make sure that your wireless adapter is compatible with the encryptiontype used by the router. Older adapters (such as 802.11b) are often notable to handle WPA or WPA2, at least not without firmware upgrade.

4.3.1. Notes on wep

ubuntu wep faq

If you have a 10 digit wep key try entering it in this format xxxx-xxxx-xx(include dashes)

Use an open setting instead of shared when using wep When using wep, check driver files such as README as some drivers need

a command to adjust the mode to work properly. Here are a coupleexamples.

Madwifi driver needs to change to authmode 2 when using shared keysetting.

manually from command line iwpriv ath0 authmode 2

add linepre-up iwpriv ath0 authmode 2 to interfaces file toautomate during boot

For ipw2200 driver interface file should say wireless-key restricted

4.3.2. Notes on wpa

Information on host AP; hostapd; wpa_supplicant

ndiswrapper w/ wpa

WPA HowTo

ipw2200 and WPA

madwifi/atheros and wpa

There have been a few posts where no association is established with router

even on an open signal. At the point of writing this line, no answer has been seento why this happens. A router reboot has been noted once to resolve but in othersituations has caused heartache as network settings need to be set up again.Booting with acpi=off or noapci should be tried.

4.4. ip assignment

Now that you have association to the router did you get an ip assigned to thedevice? This can be checked two ways.

1. Run the command ifconfig and look for an assigned ip.




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2. You can always try to ping the router with the routers ip. A lot ofhome routers use something similar to 192.168.0.1 You'll have to findwhat that ip address is to ping.

If you do not have an ip then here are things to try Using DHCP

sudo dhclient

or

sudo invoke-rc.d networking restart

after running the invoke-rc.d command try dhclient ath0 again

You may want to try and reboot making sure your networking interfacesfile is set up properly.

If you can connect to the router, but can't get an ip, it may be because you put thewrong WEP key in.

* Using Static ip assignment

sudo ifconfig down

sudo ifconfig ip addr 192.168.x.x netmask 255.255.255.0 broadcast

broadcast 192.168.x.255 up

where the x = an ip address in your network range.

sudo route add default gw dev

Now try to ping your router and a website. If you're connected now and havean ip assigned but can not surf website then move on to next section.

You will need to make sure your interfaces file is set up properly so you getinternet again when you reboot

4.5. Connected but no internet

4.5.1. DNS

If you don't know what DNS means or what it does you can go here to read




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more. Basically it takes a common name such as www.google.com andsearches a database to find the ip address of google. Then it actuallytransfers the request to download the web page via the ip address. If you are

connected to your router and have an ip address assigned to your wirelessdevice but can't search the web, you will need to check to see if you have aDNS nameserver set

A simple test to see if it's a DNS server setting is to use the pingcommand. If you can ping an external site via ip address but can't loada web page in your browser then it is possible you have a dns serverproblem.

Check this file to see if there is a dns server listed.

cat /etc/resolv.conf

search telus.net

nameserver 209.53.4.130

nameserver 209.53.4.150

You can find your dns settings if you have a working windowsmachine

For a Win 95/98 box click start>run then type winipcfg.

Choose the correct adapter and then more. In the sample above,replace telus.net with what's in the "Host Name" box. nameserver will equal what's in the dns server box.

For a Win 2000/xp box click Start>Run...type cmd click ok.type ipconfig /all. In the sample above, replace telus.net

with what's next to the field Connection-Specific DNS suffix.For name server look next to the line DNS servers.

Your DNS server settings can also be found out by calling your ispprovider and asking them.

You can set up your dns settings so they don't change. StaticDnsWithDhcp:StaticDnsWithDhcp

4.5.2. IPV6

The internet standard is currently considered ipv4. The new standard, ipv6,is slowly being implemented to replace ipv4. Because it's not widely used atthe moment, ipv6 can cause problems. It is enabled by default in Ubuntu.This can cause no internet if above seems ok.

Firefox specific




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In the address bar type about:config. Find this linenetwork.dns.disableIPv6 and double click on it to change thevalue to true.

System wide Open the file /etc/modprobe.d/aliases

Add the first three lines to the file. The line with # starting isalready in the file. Find it and add the # in front of it.

alias net-pf-10 ipv6 offalias net-pf-10 offalias ipv6 off#alias net-pf-10 ipv6

After making these changes a reboot is required.

5. Config Files

The following is a list of important config files used with wireless

/etc/network/interfacesThis is where your inteface settings for the network are kept sample

1. man interfaces has information about this file.

2. For a little more detailed info on the interfaces file look at thefile in /usr/share/doc/ifupdown/examples/network-interfaces.gz.You can read through it with the cat command and then adding |less to the end of the command.

3. For pcmcia users who want to start your card at boot do not usean auto stanza. add map to the file. So here is anexample of what it would look like.

Check your routers settings to ensure it can accept another connection.1. Check your /etc/network/intefaces file. You should have something

similar to this:

# The loopback network interface

auto lo

iface lo inet loopback

# This is a list of hotpluggable network interfaces.

# They will be activated automatically by the hotplug

subsystem.

# With lines # out these don't work. If they were removed

this would hotplug only eth0 when cable is plugged in with

active network

#mapping hotplug

# script grep




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# map eth0

#echo connects ath0 when device is hotplugged. using echo

instead of grep allows any device to be brought up when

hotplugged. Note this could cause a problem if a device isactive and another one that is mapped is plugged in.

mapping hotplug

script echo

map ath0

#interfce of ath0 device with wep setting (not all these

lines are required but show you options that may be needed)

iface inet dhcp

wireless-essid xxxx

wireless-key xxxxx

wireless-key xxxx-xxxx-xx (in certain situations a - is

needed after every 4 characters to work)

wireless-key1 xxxx (add a number after key to specify keynumber to use.)

wireless-defaultkey 1 (specifies which key is default)

wireless-key s:xxx (add s: in front of key if ascii form)

wireless-key XXXXXXXXXX open|restricted (if using

shared/restricted setting add this line)

auto

/etc/resolv.confWhere your DNS server settings are kept

/etc/modules

If a driver won't load at boot, you can add it to this list so it does

/etc/modprobe.d/blacklistIf you don't want a driver to load at boot you add it to this list. Usuallythis is used if you have a driver conflict and you want to make sure aspecific driver is used. Note: this method will not work unless it is aLKM (loadable kernel module) If driver/mod was compiled into thebase kernel, it will still load if on blacklist.

6. Connection Established, Problems Persist

This section is reserved for solutions to problems where you can getconnected but the connection is unstable. If you find a solution to yourproblem that's not here, please edit this page and add your solution.

6.1. Dropped Connections

1. One common problem is channel interference. Cordless phones and otherwireless devices can interrupt your wireless connection. If you are having aproblem with dropped connections then try using a different channel.

2. Network-Manager; Wifi-radar; and gtk wifi can cause dropped signals every




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so often as they scan the interfaces, causing the connection to drop. You cantry uninstalling these apps to see if your problem goes away, but doing sowill remove any GUI tools that you may or may not have been using to

configure and monitor your wireless connections. If removing these toolssolves your problem, please file a bug report on the product's launchpad pageto help improve the app's performance.

6.2. Connected, Issues with Certain Websites

1. Disable IPV6.

6.3. Incorrect Driver Loads at Boot

1. Some devices will have multiple drivers, and some will function better thanothers. To prevent a specific driver from loading during boot, read themodprobe command section.

7. Commands

This section gives a real brief summary of commands used to help youtroubleshoot. There are also examples of the commands discussed. For moreinformation, consult the man page of the command or do a google search.

7.1. lshw

This command shows information about hardware:

sudo lshw

We can limit the the output to show just specific devices by adding options tothe command:

sudo lshw -businfo

BusInfo Device Class Description

pci@00:1f.5 multimedia82801CA/CAM AC'97 AudioController

82801CA/CAM AC'97 Modem




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You can then use a different option to limit output so it shows just yournetworking devices.

Find your device in the list and notice it's class then:

sudo lshw -C

*-network

description: Wireless interface

product: AR5212 802.11abg NIC

vendor: Atheros Communications, Inc.

physical id: 1

bus info: pci@03:00.0

logical name: ath0

version: 01

serial: 00:11:95:50:be:62

width: 32 bits

clock: 33MHz

capabilities: bus_master cap_list ethernet physical

wireless

configuration: broadcast=yes '''driver=ath_pci

driverversion=0.9.6.0 (EXPERIMENTAL)''' ip=192.168.1.12

multicast=yes wireless=IEEE 802.11g

resources: iomemory:10800000-1080ffff irq:11

Key Points

1. Notice the configuration line. This area will tell you if there is a driver

loaded for your device. (except devices using orinoco driver, these don'tshow here) If you do not see a driver listed here then there is not one loadedand assigned to the device and it will not show up in iwconfig output or thenework-admin gui.

2. The businfo line has importance as some devices are recognized andmemory is readable but the device is not physically on the bus. This is rarebut it has been seen. It may seem cryptic but your output will vary greatlyand there needs to be some characters (other then 0) here denoting it's placein the pci bus.

TODO: describe what it means when it shows *-network UNCLAIMED, and no

pci@00:1f.6 communication Controller

pci@03:00.0 ath0 network AR5212 802.11abg NIC




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configuration line is present.

7.2. lspci

This command lists information about devices on the pci bus:

lspci -v

Lists out pci devices with information about the device. (information isdifferent then output from lshw)

You can limit the output by piping the output with grep

lspci -v | grep Ethernet

0000:03:00.0 Ethernet controller: Atheros Communications, Inc. AR521

Inc. AR5212 802.11abg NIC (rev 01)

'''Subsystem: D-Link System Inc D-link DWL-G650

(Rev B5)''' Wireless cardbus adapter

Flags: bus master, medium devsel, latency 168, IRQ

11

Memory at 10800000 (32-bit, non-prefetchable)

[size=64K]

Capabilities: [44] Power Management version 2

command:

sudo lspci -n

0000:03:00.0 0200: '''168c:0013''' (rev 01)

Key Points

1. This command shows the revision of the card (in above example the revisionof the card is B5 not 01).

2. Using the -n option you can find the PCI ID (168C:0013) of the card and




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find the correct driver to use with ndiswrapper. ndiswrapper list

7.3. lsusb

This command lists information about devices on the usb bus.

sudo lsusb -v

$ lsusb

Bus 005 Device 001: ID 0000:0000Bus 001 Device 001: ID 0000:0000

Bus 004 Device 002: ID 2001:3700 D-Link Corp. [hex] DWL-122

802.11b

Bus 004 Device 001: ID 0000:0000

Bus 003 Device 001: ID 0000:0000

Bus 002 Device 001: ID 0000:0000

7.4. lsmod

This command simply shows what modules are loaded and running.

sudo lsmod

When the command lshw was run, you saw the name of the driver allocated tothe device. You can pipe this command through grep to limit the output.

lsmod | grep ath

ath_pci 78908 0

ath_rate_sample 16776 1 ath_pci

wlan 141532 4

wlan_wep,ath_pci,ath_rate_sample

ath_hal 148432 3 ath_pci,ath_rate_sample

7.5. modprobe




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modprobe runs or stops a module from running. Most wireless drivers inbreezy are in a module form. The following commands remove or add amodule.

When a recognized device loads, the kernel automatically loads the correctmodule for the device. This command is only needed to manually run a module

To start a module run this command:

sudo modprobe

To stop and remove a module run this command:

sudo modprobe -r

7.6. iwconfig

This command prints information about a wireless interface and allows youto configure the network interface from the command line.

sudo iwconfig

* eth0 no wireless extensions.

* ath0 IEEE 802.11g ESSID:"XXXXX"

Mode- Managed '''Frequency- 2.437

GHz''' '''Access Point- 00:17:16:1D:FC:DE'''

Bit Rate-36 Mb/s Tx-Power-18 dBm

Sensitivity=0/3

Retry- off RTS thr:off Fragment thr- off

Encryption key:xxxx-xxxx-xx Security

mode:restrictedPower Management off

Link Quality=50/94 Signal level=-45 dBm Noise

level=-95 dBm

Rx invalid nwid:10911 Rx invalid crypt:0 Rx

invalid frag:0

Tx excessive retries:0 Invalid misc:0 Missed

beacon:0

Key Points

1. This example shows the interface of ath0. If you do not see anything like this




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sample then you do not have a working driver.2. The interface may not be named "ath0". It could say "wlan1". You may need

to use the correct interface name to configure WICD or other wireless

manager.3. Access Point: If you see all zeros here or nothing then you are notconnected/associated to your router. When you are connected it will showthe mac address of the router here.

4. Frequency more commonly known as channel. If you can not connect toyour router ensure frequency is correct.

You can not set the channel(currently with breezy or earlier) via the networkgui. Most drivers are set up as auto so it changes to the corresponding channel ofthe ap you're trying to connect to. But if you must make the change then this is thecommand to change it.

sudo iwconfig channel

or

sudo iwconfig freq

7.7. ifconfig

Channel/FrequencyChart

Ch 1 2.412

Ch 2 2.417

Ch 3 2.422Ch 4 2.427

Ch 5 2.432

Ch 6 2.437

Ch 7 2.442

Ch 8 2.447

Ch 9 2.452

Ch 10 2.457

Ch 11 2.462

Ch 12 2.467

Non US Channels

Ch 13 2.472

Ch 14 2.484




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This command is similar to iwconfig with the following differences. It's a more general networking command. It works with any interface

whether wireless or wired.

It's configuration options and output show different networkingreferences or set different settings.

sudo ifconfig

ath0 Link encap:Ethernet HWaddr 00:11:95:50:BE:62

inet addr:192.168.1.11 Bcast:192.168.255.255

Mask:255.255.255.0inet6 addr: fe80::211:95ff:fe50:be62/64 Scope;Link

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:32568 errors:162786 dropped:0

overruns:0 frame:162786

TX packets:17252 errors:0 dropped:0 overruns:0

carrier:0

collisions:0 txqueuelen:200

RX bytes:20362191 (19.4 MiB) TX bytes:6778264

(6.4 MiB)

Interrupt:11 Memory:d0c80000-d0c90000

Key Points

1. The benefit with ifconfig on a wireless device is it shows if you have an ipaddress assigned to the device which is noted next to inet addr. iwconfigmay show you're connected to your router but you still have no internetconnection with out an ip address assigned to the device.

7.8. iwlist

This command will give you more detailed information from the wireless

interface such as a scan of all available routers with in range.

sudo iwlist scan

ath0 Scan completed :

Cell 01 - Address: 00:13:46:1D:BC;0E

ESSID:"xxx"




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Mode: Master

Frequency: 2.437 GHz (Channel 6)

Quality=49/94 Signal level=-46 dBm

Noise level=-95 dBm

Encryption key:onBit Rate:1 Mb/s

Bit Rate:2 Mb/s

Bit Rate:5 Mb/s

Bit Rate:6 Mb/s

Bit Rate:9 Mb/s

Bit Rate;11 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

Extra bcn_int=100

Key Points

1. If you get a completed scan like example, then your device and driver isprobably working properly.

2. Some devices do not support scanning so this command may not work foryou.(such as orinoco cards)

7.9. dhclient

dhclient is simply the program that deals with dhcp if you're dealing with arouter running as a dhcp server.

sudo dhclient

If you are associated with your router try running this command to get ip andother information to set up connection.

7.10. ping

ping is a good troubleshooting command to track down where the connectionproblem may be: First ping your local loopback device

ping -c 4 127.0.0.1

If this doesn't work then there is a problem in the tcp/ip stack some where.

If the device is assigned an ip address next ping that. use ifconfig to findthe ip address assigned to the device




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ping -c 4

Next ping your router

ping -c 4

Next ping an external site using the ip address

ping -c 4 216.239.57.99

Next ping using common name

ping -c 4 www.google.com

If you can ping an external site with the ip address but not the common namethen there is a dns nameserver problem

7.11. Links

These are sites with information on wireless networking:

linux wireless access point HOWTO

Wireless linux resourcestldp Linux networking howto

Debian Network ConfigurationSurvey of Linux and Wifi

CategoryNetworking CategoryWireless

WifiDocs/WirelessTroubleShootingGuide (last edited 2009-10-16 01:07:05 byZoubidoo)


Documents

Wireless Troubleshoot