Network Unreachable on Ubuntu 7.04

glok_twen · 06-24-2007, 09:57 PM

Hi - I have previously had this network up and running on my Ubuntu machine. Then it inexplicably stopped. Here is some more info, can you please help:

- ubuntu 7.04 64bit version running on dual core 3800+
- the command "host gmail.com" seems to return success ("gmail.com has address 64.233.171.83 ...." - meaning DNS is working correctly???)
- ping gmail.com returns: "connect: Network is unreachable"
- can not browse the internet or run any other program that reaches outside the router
- resolv.conf has the correct router address
- successfully can ping router from ubuntu
- other nodes on my lan can ping the ubuntu machine
- can access router with browser
- can print successfully to my wireless print server on the lan
- static ip is being setup correctly
- have done multiple reboots and /etc/init.d/networking restart all to no avail
- this seemed to start during the next session after i got moblock up and working

checked everything i about networks - can you suggest a next step to check or tweak??

thanks,
GT

ajaimes · 06-25-2007, 12:11 PM

Please run this command and paste its result:

ip route show all

framp · 06-25-2007, 01:05 PM

I created a small script which does some network configuration analysis for common network configuration errors and gives hints how to solve the problem. It might also help you to detect the cause of your network problem.

It's unfortunately never tested on Ubuntu. I'd appreciate if you just could execute this script and either post the output in this thread or give me feedback whether it works on Ubuntu or fails.

Thx.

glok_twen · 06-25-2007, 07:44 PM

framp and ajaimes - thanks so much for the pointers. i will start researching what this means but if you have suggestions or can see what's wrong please let me know. here is what i got:

Code:

root@jeff-2007-pavilion:/home/framp# ip route show all
192.168.1.0/24 dev eth0  proto kernel  scope link  src 192.168.1.80
169.254.0.0/16 dev eth0  scope link  metric 1000

(not quite sure how to interpret this but i'll go read about it. btw my router is 192.168.1.1 and the ubuntu node is 192.168.1.80)

and framp from your script:

Code:

root@jeff-2007-pavilion:/home/framp# ./collectNWData.sh
!!! Script tested on SuSE systems only. Data collection and analysis steps may fail and is ignored!
!!! Script tested on SuSE systems only. Data collection and analysis steps may fail and is ignored!
!!! Script tested on SuSE systems only. Data collection and analysis steps may fail and is ignored!
collectNWData.sh V0.4.5

--- What's the type of networktopology?
--- (1) DSL modem <---> LinuxClient
--- (2) DSL (Linux)Router <---> LinuxClient
--- (3) DSL modem <---> (Linux)Router <---> LinuxClient
--- (4) DSL router <---> (Linux)Router <---> LinuxClient
--- Please answer with 1-4:2

--- On which host is the script executed?
--- (1) LinuxClient
--- (2) LinuxRouter
--- Please answer with 1-2:1
--- Collecting information about your networkconfiguration...
--- Analyzing the collected data for common errors...
!!! Neither a network card nor a wireless card was found on the system.
>>> Check whether your hardware card was plugged in correctly.
!!! The system can't ping an external IP address.
>>> Set a default gateway on your system
!!! The system can't resolve an external DNS name.
>>> Check the nameserver definition in /etc/resolv.conf
--- Configuration errors detected. Please read and follow the messages marked with >>> above.
--- If you don't have success post the contents of file collectNWData.out.

glok_twen · 06-25-2007, 08:22 PM

ifconfig:

Code:

jeff@jeff-2007-pavilion:~$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:xx:xx:xx:xx:xx
          inet addr:192.168.1.80  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::xxx:xxxx:xxxx:xxxx/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:15379 errors:0 dropped:0 overruns:0 frame:0
          TX packets:19545 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:9826178 (9.3 MiB)  TX bytes:18371526 (17.5 MiB)
          Interrupt:22

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:36 errors:0 dropped:0 overruns:0 frame:0
          TX packets:36 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:3316 (3.2 KiB)  TX bytes:3316 (3.2 KiB)

iptables:

Code:

jeff@jeff-2007-pavilion:~$ sudo iptables -L
Password:
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
jeff@jeff-2007-pavilion:~$

resolv.conf:

Code:

# generated by NetworkManager, do not edit!



nameserver 192.168.1.1

glok_twen · 06-26-2007, 01:07 AM

so through the research and guessing process i entered:

sudo route add default gw 192.168.1.1

... and all of a sudden i can get out again ... hoooo-rah

but, it disppears at re-boot.

first, what actually did this command do?
then, is this the right fix and can i make it permanent?
finally, any speculation on how this could have been inadvertently changed?

thanks

framp · 06-26-2007, 01:43 PM

@glok_twen: Thx for your test.

Quote:

!!! The system can't ping an external IP address.
>>> Set a default gateway on your system

That's what you fixed with route add default gw 192.168.1.1.

Quote:

!!! Neither a network card nor a wireless card was found on the system.
>>> Check whether your hardware card was plugged in correctly.

That's a bug because according ifconfig you have a NIC. Could you do me the favor and post the output of lspci on your system so I can fix this bug?

Thx.