Cannot ping outside university

[Tod Merley]

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