Cannot ping outside university

[Henk Koster]

On Mon, 04 Sep 2006 10:01:01 -0700, Tod Merley wrote:

> On 9/4/06, David <dpleydel at univ-fcomte.fr> wrote:
>> About fie weeks ago I installed Dapper on a Dell Inspiron 6000
>> laptop. Everything was going great, I configured the eth0 interface to
>> get onto the university network and I could connect to Ubuntu
>> repositories and I downloaded various software eg. GRASS, R etc.
>>
>> Then some days later I lost the internet connection. I do not know
>> why. I can still ping my PC and the PC can still ping the laptop. But
>> the laptop cannot ping websites or repos.
>>
>> To make matters worse, we need this sorted within the next 24 hours!
>> Any help would be greatly appreciated.
>>
>> dave
> 
> Hi dave!
> 
> Lets get started!
> 
> How I snoop net problems (watch!):
> ---------------------------------------------------------------
> tod at tod-desktop:~$ ifconfig
> eth0      Link encap:Ethernet  HWaddr 00:15:4D:23:8D:A1
>           inet addr:192.168.X.X  Bcast:192.168.X.255  Mask:255.255.255.0
>           inet6 addr: fe80::210:4bff:fe21:8da1/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:3334411 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:2419924 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:189 txqueuelen:1000
>           RX bytes:698219965 (665.8 MiB)  TX bytes:189143239 (180.3 MiB)
>           Interrupt:10 Base address:0x9800
> 
> 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:154 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:154 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:15996 (15.6 KiB)  TX bytes:15996 (15.6 KiB)
> 
> tod at tod-desktop:~$ route
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
> 192.168.0.0     *               255.255.255.0   U     0      0        0 eth0
> default         192.168.0.1     0.0.0.0         UG    0      0        0 eth0
> 
> tod at tod-desktop:~$ cat /etc/resolv.conf
> search domain.actdsltmp
> nameserver 205.171.3.65
> tod at tod-desktop:~$ cat /etc/hosts
> 127.0.0.1 localhost tod-desktop
> --------------------------------------------------------------
> ifconfig shows the ethernet link as normal (if you are using wireless
> then use iwconfig also).
> 
> route is very important for you.  Do you show a default  user gateway?
>  I do (see the line with the "UG" lable).
> 
> /etc/resolv.conf is the file used by network users to find the Domain
> Name Service servers (name servers).  Without this service your
> network applications would sent a DNS query for say www.google.com but
> never recieve an answer (you might ping the IP address 66.102.7.104
> and get a reasonable return but ping the name and it never replies).
> 
> Now ping the gateway, the nameserver, and look at it all again.
> 
> There are manuals on all the above mentioned commands (man ifconfig)
> which also point to other useful tools (see the "see also" usually at
> the bottom of the man page).  Read them.
> 
> Good Hunting!
> 
> Tod

Good advice, but I have a suspicion that the OP is running packages 
like network-manager (nm-applet, not gnome-network-manager) and/or
resolvconf. Especially this last package is nothing but trouble IMHO... My
advice: before following Tod Merley's advice: get rid of network-manager
and resolvconf if he has them installed.