[SOLVED] Network suddenly not reachable

fukda · 02-13-2011, 09:53 AM

Hi,
here's my Problem:
Until yesterday everthing was working perfectly. Today I started my Debian Lenny and internet doesn't work.

I can't ping my router successfully:

Code:

takada:/home/sam# ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
From 192.168.1.97 icmp_seq=1 Destination Host Unreachable
^C
--- 192.168.1.1 ping statistics ---
6 packets transmitted, 0 received, +1 errors, 100% packet loss, time 5000ms
, pipe 4

Nor can i ping that computer from another computer in the network:

Code:

DieMaschine:/home/bea# ping 192.168.1.97
PING 192.168.1.97 (192.168.1.97) 56(84) bytes of data.
From 192.168.1.5 icmp_seq=1 Destination Host Unreachable
From 192.168.1.5 icmp_seq=2 Destination Host Unreachable
From 192.168.1.5 icmp_seq=3 Destination Host Unreachable
^C
--- 192.168.1.97 ping statistics ---
4 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3017ms
, pipe 3

This whole thing is really strange because I didn't change any network settings. It just failed to work.
Internet works on every machine except that one.
LED lights are on both on router and on network card of that computer.

Ifconfig says following:

Code:

eth0      Link encap:Ethernet  HWaddr 00:15:e9:7c:ed:7f  
          inet addr:192.168.1.97  Bcast:192.168.1.255  Mask:255.255.255.0
          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:21 Base address:0xb800 

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:280 errors:0 dropped:0 overruns:0 frame:0
          TX packets:280 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:27670 (27.0 KiB)  TX bytes:27670 (27.0 KiB)

I really tried to find a solution but I failed. So thanks for any help.

repo · 02-13-2011, 09:57 AM

Welcome to LQ

Try to verify or change the networkcable.
Verify the settings of the router.
Verify the default GW

Kind regards

fukda · 02-13-2011, 10:15 AM

Thank you for answering.
I tested that networkcable with a laptop which worked properly.
"route add default gw 192.168.1.1" also didn't change anything.
I just looked up my router settings. It doesn't recognize my computer under plugged devices but its settings are just normal which worked well since 2 years and and also now with all other computers.
So I think it has to do something with that computer.
There also was an error message while system restart related to networking, something like

Code:

Failed to bring up eth1
siocaddrt no such process

, but I still have no idea what to do, since I'm trying to use eth0 not eth1.

repo · 02-13-2011, 10:19 AM

Perhaps the network card is broken.

Kind regards

fukda · 02-13-2011, 10:21 AM

I thought this way, too. But having two network cards (eth0, eth1) I tried both already. Same result.

fukda · 02-13-2011, 10:32 AM

Whoa! Somehow the names of the two network cards changed. Then when I configured my computer to use eth0 the networkcable was in eth1 and the other way round. I'm just wondering how this could happen.
So sorry for disturbing you and thank you for your help.

Regards.

repo · 02-13-2011, 10:36 AM

You can mark the thread solved using the thread tools.

Kind regards

jamesf · 02-13-2011, 06:45 PM

Quote:

Originally Posted by fukda

Whoa! Somehow the names of the two network cards changed. Then when I configured my computer to use eth0 the networkcable was in eth1 and the other way round. I'm just wondering how this could happen.
So sorry for disturbing you and thank you for your help.

Regards.

Network cards (and other devices) are enumerated by udev. If the enumeration order changes then the names of the cards gets swapped (names of hard drives, usb drives, etc. can change, too). The way to solve this is to write custom udev rules that assign the device name based upon unique characteristics of the cards. So, you'd write a couple of rules that basically say "For Intel NIC, assign eth0" and "For realtek NIC, assigh eth1". Then you would no longer be subject to the vagaries of enumeration order.

The exact syntax is different for different devices. I haven't had to worry about this for several udev revisions, so my knowledge of configuration is dated.

Hope this helps you get things sorted.