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Old 05-29-2013, 05:30 PM   #1
confgr
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No network connectivity


Hi all,

I just got a new Lenovo Thinkpad T430, to which Scientific Linux 6.4 was installed. All features work perfectly at my workplace (where installation was done). Among others, wireless and wired internet connections worked as expected.

When I brought the laptop at home, I realised that internt doesn't work (wired or wireless) although I get notifications that connection to my router is successful. I also cannot ping anything,

The only error message I see is through Google Chrome, which gives:

Error 137 (net:: ERR_NAME_RESOLUTION_FAILED): Unknown error

Mozilla also doesnt connect to anything, but gives no specific error message.

The only thing I found for the Chrome type of message is that when i appears in Windows systems, a solution is to give:

netsh winsock reset

Anyone knows what does this command do and if there is anything similar for Linux systems? Or in general: does anyone have clue of what is going on and how it can be fixed?

Thanks a lot in advance
 
Old 05-30-2013, 03:20 AM   #2
Nikosis
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Welcome to LQ

It looks like your DNS nameserver is mixed up

Did you try to restart your network
Code:
/etc/rc.d/init.d/network restart
 
Old 05-30-2013, 03:44 AM   #3
TenTenths
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Check your /etc/resolv.conf and make sure that it's using legitimate name servers and not something on your company network.

See if you can ping 8.8.8.8 and if you can then use that as a nameserver.
 
Old 05-30-2013, 03:57 AM   #4
confgr
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Thanks a lot for the answer.

I gave the command you told me and here is the output:

Quote:
sudo /etc/rc.d/init.d/network restart
Shutting down interface Auto_WLAN-001F3F8FEEBF: Device state: 3 (disconnected) [ OK ]
Shutting down interface eth0: Error: Device 'eth0' (/org/freedesktop/NetworkManager/Devices/0) disconnecting failed: This device is not active [FAILED]
Shutting down interface wlan0: Error: Device 'wlan0' (/org/freedesktop/NetworkManager/Devices/1) disconnecting failed: This device is not active [FAILED]
Shutting down loopback interface:[ OK ]
Bringing up loopback interface:[ OK ]
Bringing up interface Auto_WLAN-001F3F8FEEBF: Active connection state: activating
Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/2
state: activated
Connection activated [ OK ]
Bringing up interface wlan0: Error: No suitable device found: no device found for connection 'System wlan0'.[FAILED]
Wireless appears connected after all this, with a strong signal, but still no internet access.

Also, when I ping my router:

ping -cl 192.168.2.1

I get "bad number of packets to transmit"

The laptop is set-up as dual boot, with a small Windows 7 partition. I tested the internet through Windows and all works fine.

All these tests were done with wireless connection. I assume the result will be the same with wired connection, but didn't try yet.
 
Old 05-30-2013, 04:20 AM   #5
confgr
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Quote:
Originally Posted by TenTenths View Post
Check your /etc/resolv.conf and make sure that it's using legitimate name servers and not something on your company network.

See if you can ping 8.8.8.8 and if you can then use that as a nameserver.
Thanks. I checked my /etc/resolv.conf and it contains:

Quote:
domain speedport.ip
search speedport.ip
nameserver 192.168.2.1
Speedport is the type of my router and the IP is also correct.

I checked also ping 8.8.8.8

At first it worked:
Quote:
64 bytes from 8.8.8.8: icmp_sqe=1 ttl=50 time=21.7 ms
I then changed nameserver to 8.8.8.8 in resolv.conf (is that what I should do?)

Internet connected briefly but soon I got back the earlier error message:

Quote:
Error 137 (net:: ERR_NAME_RESOLUTION_FAILED): Unknown error
After that I did again ping 8.8.8.8 which works only temporarily, giving me about 80-90% packet loss
 
Old 05-30-2013, 04:32 AM   #6
TenTenths
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You probably don't need the domain and search options in /etc/resolv.conf, 8.8.8.8 is Google's public name server and to be honest it's pretty solid so I've no idea why you'd be getting such a large packet loss.

I would strongly suggest you try this with the wired connection and see what happens. In general wired connections are more "robust" and less prone to issues with drivers etc.

Last edited by TenTenths; 05-30-2013 at 04:46 AM.
 
Old 05-30-2013, 04:44 AM   #7
Nikosis
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Quote:
domain speedport.ip
search speedport.ip
nameserver 192.168.2.1
try to comment first two out, you don't need that. Is it from your work?
Code:
#domain speedport.ip
#search speedport.ip
nameserver 192.168.2.1

Last edited by Nikosis; 05-30-2013 at 04:53 AM.
 
Old 05-30-2013, 05:14 AM   #8
confgr
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Ok, try all the above but no luck.

-Commented out "domain" and "search" entries
-Used wired connection with namespace to 8.8.8.8

Doing ping 8.8.8.8 always works after I restart the network with /etc/rc.d/init.d/network restart

But it consistently goes up to icmp_sqe=8 and then follows 100% packet loss.

I am not sure how it can be a driver problem. As said, both wireless and wired connection worked well at my workplace.

Could this be a Network Manager problem? Will an installation of another network handler help?
 
Old 05-30-2013, 05:21 AM   #9
Nikosis
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Quote:
Originally Posted by confgr View Post
Ok, try all the above but no luck.

-Commented out "domain" and "search" entries
-Used wired connection with namespace to 8.8.8.8

Doing ping 8.8.8.8 always works after I restart the network with /etc/rc.d/init.d/network restart

But it consistently goes up to icmp_sqe=8 and then follows 100% packet loss.

I am not sure how it can be a driver problem. As said, both wireless and wired connection worked well at my workplace.

Could this be a Network Manager problem? Will an installation of another network handler help?
I wouldn't change your nameserver to 8.8.8.8, if it's already at your router, if it's not you can change it there, but you don't need to. In resolv.conf leave 192.168.2.1

Another thing is every time you restart your network, resolv.conf is overwritten by /sbin/dhclient-script and those settings can be changed in /etc/sysconfig/network-scripts/ifcfg-* files

Last edited by Nikosis; 05-30-2013 at 05:29 AM.
 
Old 05-30-2013, 06:19 AM   #10
markotitel
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are you shure your router keeps connected to the internet?
 
Old 05-30-2013, 08:15 AM   #11
confgr
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Quote:
Originally Posted by markotitel View Post
are you shure your router keeps connected to the internet?
Well, I have one more laptop and two smartphones continuously connected to this router while I am doing all these tests. No problem with those.

One thing I noticed also is that at startup of SL, I get this error: wlan0: "no link present. Check cable?"

When I log in then, I can connect, just internet is not working
 
Old 05-30-2013, 06:58 PM   #12
MikeDeltaBrown
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Maybe your router limits the number of pings allowed THROUGH it and, hopefully, not TO it. When the external pings stop, can you still ping 192.168.2.1?

Post the output of these commands:
route -n
ifconfig -a

Check to see that the output of 'route' and 'ifconfig' are the same before and after the ping limit is reached.

I have had laptops with intermittent wireless adapters... could be that.

In your command 'ping -cl 192.168.2.1', is the argument to -c a one or an L? Should be one.
 
Old 05-31-2013, 01:36 AM   #13
confgr
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Quote:
Originally Posted by MikeDeltaBrown View Post
Maybe your router limits the number of pings allowed THROUGH it and, hopefully, not TO it. When the external pings stop, can you still ping 192.168.2.1?

Post the output of these commands:
route -n
ifconfig -a

Check to see that the output of 'route' and 'ifconfig' are the same before and after the ping limit is reached.

I have had laptops with intermittent wireless adapters... could be that.

In your command 'ping -cl 192.168.2.1', is the argument to -c a one or an L? Should be one.
Yes, ping to 192.168.2.1 continues after the external ones freeze. And yes, you are correct that -cl was an error command I was giving before. Noticed that late last night. I can't perform the commands you suggest now because I left for a trip. I will check again in a week when I come back. I need to use wireless with scientific Linux in the place I am going so I still hope that the problem is with my home router and not some settings from my workplace. Some searches I did show that the speedport router typically used by Telekom here in Germany causes similar problems to many Linux users.
 
Old 06-16-2013, 04:24 PM   #14
confgr
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Quote:
Originally Posted by MikeDeltaBrown View Post
Maybe your router limits the number of pings allowed THROUGH it and, hopefully, not TO it. When the external pings stop, can you still ping 192.168.2.1?

Post the output of these commands:
route -n
ifconfig -a

Check to see that the output of 'route' and 'ifconfig' are the same before and after the ping limit is reached.

I have had laptops with intermittent wireless adapters... could be that.

In your command 'ping -cl 192.168.2.1', is the argument to -c a one or an L? Should be one.
So back from my business trip (where actually wireless access was working with no problems at all).

Here is the output of route -n command (same before and after ping limit is reached):

Code:
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.2.0     0.0.0.0         255.255.255.0   U     0      0        0 vmnet8
192.168.2.0     0.0.0.0         255.255.255.0   U     2      0        0 wlan0
192.168.191.0   0.0.0.0         255.255.255.0   U     0      0        0 vmnet1
0.0.0.0         192.168.2.1     0.0.0.0         UG    0      0        0 wlan0
Here is the output from ifconfig -a
Code:
eth0      Link encap:Ethernet  HWaddr 00:21:CC:D7:60:05  
          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:20 Memory:f3900000-f3920000 

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:2454 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2454 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:209488 (204.5 KiB)  TX bytes:209488 (204.5 KiB)

vmnet1    Link encap:Ethernet  HWaddr 00:50:56:C0:00:01  
          inet addr:192.168.191.1  Bcast:192.168.191.255  Mask:255.255.255.0
          inet6 addr: fe80::250:56ff:fec0:1/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:47 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

vmnet8    Link encap:Ethernet  HWaddr 00:50:56:C0:00:08  
          inet addr:192.168.2.1  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::250:56ff:fec0:8/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:50 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

wlan0     Link encap:Ethernet  HWaddr 3C:A9:F4:18:54:04  
          inet addr:192.168.2.131  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::3ea9:f4ff:fe18:5404/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1599 errors:0 dropped:0 overruns:0 frame:0
          TX packets:113 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:314799 (307.4 KiB)  TX bytes:19373 (18.9 KiB)
After the ping limit, the entry for wlan0 is the following:

Code:
wlan0     Link encap:Ethernet  HWaddr 3C:A9:F4:18:54:04  
          inet addr:192.168.2.131  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::3ea9:f4ff:fe18:5404/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1651 errors:0 dropped:0 overruns:0 frame:0
          TX packets:129 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:325876 (318.2 KiB)  TX bytes:21256 (20.7 KiB)
 
Old 06-17-2013, 10:47 AM   #15
MikeDeltaBrown
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It looks like you have VM-Ware installed and it is configuring the interface 'vmnet8' with the same IP address as your router.

Try everything as before.
Then enter:

ifconfig vmnet8 down (assuming it was still assigned 192.168.2.1)

Try accessing the internet again.

If that fixes it, you'll have to figure out how to assign a different IP address to 'vmnet8' during boot.

Oh, and the reason the pings to 192.168.2.1 were working and the internet was not is because you were pinging yourself, not the router.

Last edited by MikeDeltaBrown; 06-17-2013 at 11:00 AM. Reason: Added the last paragraph.
 
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