no more internet access

[Ice9]

the strangest thing happened to my younger son's box.
All of a sudden his internet connection stopped working.
I figured it waould be just a matter of renewing the ip address but to my surprise eth0 still had an active ip address.
I could ping the other pc's on the network, could access the router and all only no outside address can be reached.
Nothing I tried until now worked.
Could the network card still be faulty, even if it can be used to browse the internal network?

[Void Main]

If you have connectivity to the local network but not beyond your router it would indicate his gateway address is not set on his machine (default route). I have no idea how/why it would just disappear without a change on the DHCP server or on the client. Take a look at his routing table with "netstat -rn".

[Ice9]

Ok, today I have no connectivity at all anymore.

netstat -rn showed nothing but an empty routing table.
So I configured it manually
ifconfig -a 192.168.0.111 netmask 255.255.255.0
and then did
route add default gw 192.168.0.1 (which is the address of my gateway)

any ping attempt turns out to be a "destination host unreachable"

I plugged 2 other nic's in there, I even switched them to another pci slot just to be sure .... nothing worked.
Motherboard?

[Void Main]

Do you have a laptop that you can plug into that same cable/port and verify the cable/port is good? Did you run "ethtool eth0" as root to see what the link status is?

I really doubt a hardware issue on the computer itself and if there was one it would surely show up in the output of the "dmesg" command. Between that and /var/log/messages after you try and bring the interface up might give you some clue as to where the problem is.

[Ice9]

Well I did as you mentioned and sure enough there was nothing suspicious in the logs.
So I followed your other suggestion and grabbed my work laptop (I don't own one myself yet), switched off the proxy settings and plugged the network cable into the RJ45 port, couldn't get an ip ...
I then took my Devolo dLan wireless extender (upstairs every box connects through wired powerline adapters) and tried to get an ip again, no luck...
Plugged the wireless adapter into a socket in another room and sure enough I got an ip????
Tried a couple of times to plug it back into the first socket and every time I did I got no connection, moving it to the second room got me a connection every time.
So I plugged the wired adapter in the second room, got an longer ethernet cable and did a dist-upgrade, after that plugged the adapter back in the socket from the first room and the connection was still there????

This is quite a long post to tell you that it was basically an electrical problem and that I don't know how it went away, but my younger one is happy he can watch Southpark on youtube again
Thank you for your help as always, and if you have any clue as to how the problem got solved please tell me

[Void Main]

I have never used one of those things so I don't have any idea what could have went wrong with it. Glad you got it sorted out though!

[Ice9]

Actually there was nothing wrong with the adapter because in another room it worked fine, it was that one particular room where none of the adapters would work ...

Weird, anyway it still works so I guess it's ok