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Interpreting output from ifconfig & iwconfig

Posted on 2006-07-03
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Last Modified: 2013-12-15
Hi

Being new to Linux (Suse 10.1) I'm having some problems interpreting the output from ifconfig and iwconfig. There's something stopping my wireless network from functioning correctly but I can't spot what it is. Is there something in the following output that doesn't look right? Or is there another query I can run which might tell me why my connection isn't working?

Output from 'ifconfig -a':

eth0      Link encap:Ethernet  HWaddr 00:02:3F:82:34:EB
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
          Interrupt:185 Base address:0xe800

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:104 errors:0 dropped:0 overruns:0 frame:0
          TX packets:104 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:7522 (7.3 Kb)  TX bytes:7522 (7.3 Kb)

sit0      Link encap:IPv6-in-IPv4
          NOARP  MTU:1480  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

wlan0     Link encap:Ethernet  HWaddr 00:12:17:41:79:50
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:3 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:332 (332.0 b)  TX bytes:90 (90.0 b)
          Interrupt:177 Memory:36000000-36002000

Output from 'iwconfig':
lo        no wireless extensions.

eth0      no wireless extensions.

wlan0     IEEE 802.11g  ESSID:"linksys"
          Mode:Managed  Frequency:2.462 GHz  Access Point: 00:06:25:2C:68:3B
          Bit Rate:11 Mb/s   Tx-Power:14 dBm
          RTS thr:2347 B   Fragment thr:2346 B
          Encryption key:off
          Power Management:off
          Link Quality:100/100  Signal level:-53 dBm  Noise level:-256 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

sit0      no wireless extensions.
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Question by:Nicola-H
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by:rindi
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Sorry, I think I forgot about your other Q about this (blush). To me this looks OK. What happens with the following commands?

iwlist wlan0 scan
iwconfig wlan0 essid ESSID
iwlist wlan0 scan
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by:Nicola-H
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No probs - I'm sure you're very busy being a technical genius and I appreciate any help at all :-)

I'll post the output for those commands in a couple of hours when I have access to the lappy.
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by:rindi
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I'll be off anyway for a couple of hours, so no problem.
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by:bmquintas
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To me the only thing missing in there is an ip address associated with wlan0

Have you tried :

 dhclient wlan0

?
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by:Nicola-H
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iwlist wlan0 scanoutputs this:
wlan0     Scan completed :
          Cell 01 - Address: 00:06:25:1A:9E:D4
                    ESSID:"linksys"
                    Protocol:IEEE 802.11b
                    Mode:Managed
                    Frequency:2.462 GHz (Channel 11)
                    Quality:0/100  Signal level:-63 dBm  Noise level:-256 dBm
                    Encryption key:off
                    Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s
                    Extra:bcn_int=100
                    Extra:atim=0

wconfig wlan0 essid ESSID doesn't do anything obvious, and iwlist wlan0 scan again outputs this:

wlan0     Scan completed :
          Cell 01 - Address: 00:06:25:1A:9E:D4
                    ESSID:"linksys"
                    Protocol:IEEE 802.11b
                    Mode:Managed
                    Frequency:2.462 GHz (Channel 11)
                    Quality:0/100  Signal level:-65 dBm  Noise level:-256 dBm
                    Encryption key:off
                    Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s
                    Extra:bcn_int=100
                    Extra:atim=0

dhclient wlan0  outputs this:
Listening on LPF/wlan0/00:12:17:41:79:50
Sending on   LPF/wlan0/00:12:17:41:79:50
Sending on   Socket/fallback
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 5
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 5
DHCPOFFER from 192.168.1.1
DHCPREQUEST on wlan0 to 255.255.255.255 port 67
DHCPACK from 192.168.1.1
bound to 192.168.1.101 -- renewal in 1440 seconds.

The router is set to assign IP addresses on connection.

I can still see linksys in the connection list, but it just tries to connect for a while and then fails when I select it.

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bmquintas earned 250 total points
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Well, that's a different story now, in the above you received the IP address 192.168.1.101 from a DHCP (router) server at 192.168.1.1

you should be able to ping 192.168.1.1 , meaning you have communication between the router and the pc.

Probably just a tweaking now (i guess!), if you can ping 66.249.85.104 , but you can't browse www.google.com you probably have a bad dns  config (or firewall rules in the router??)

you can use the route command to show what routes are configured on your pc, and what interfaces does it uses to reach them, just type route
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by:Nicola-H
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'Route' gives me this lot:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
loopback        *                       255.0.0.0           U     0         0            0 lo

I can't ping 66.249.85.104 - I just get 'network is unreachable'.

If I plug the lappy in with an ethernet cable it connects straight away. There's no firewall active on the laptop and all security settings on the router have been turned off. I know the card works cos I've tested it in another machine. I get the feeling I'm missing something obvious but I'm so unfamiliar with the OS that I can't see it.
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by:rindi
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Is the Access Point your DHCP server? If so you must make sure it is correctly setup to pass the correct values to your PC. If you aren't using an internal LAN you need to connect to, the AP should have a subnet mask like 255.255.255.0 set, the DNS servers of your ISP should be set too. If your using an internal LAN we may need to have more info about that, and then ideally the AP shouldn't be the DHCP server, but a server on your LAN.
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by:Nicola-H
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The access point is a wireless/wired Linksys ADSL router. It seems to be set up correctly - I have 2 wireless networked machines (a Mac and a PC) which are currently connecting via the router with no problem, and another wired one which works fine. The problem seems to be at the laptop end of things unless there are router settings that work with Mac/Win but not Linux?

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by:ircpamanager
ircpamanager earned 250 total points
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what does your /etc/resolv.conf file have in it.
make sure it has your nameserver in it:
search <your domain or ip's domain>
nameserver <your dns or ip's dns server>


after you run dhclient and obtain ip from router, type ifconfig again to see if  wlan0 has ip address in it.
if all that looks good try to ping router.
Post back your results
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by:Nicola-H
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After a great deal of struggling I decided to give up on ndiswrapper, downloaded DriverLoader, tried one last time to connect to the internet before I started installing it, and it worked. I have no idea how it got from not working to working without my doing anything, but I'm sure it was something you guys got me to do.

Thanks for all your help :-)
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