Ubuntu box keeps dropping wired network connection

Question

good morning all.

Odd one for you...

I have an Ubuntu box, 11.04 x64, running on a Dual Opteron SFF box (iWill ZMaxDP... pretty old machine). Up until a few weeks ago, it was acting as a Windows 2008 Server, but i moved it to Ubuntu.

Anyway, the machine will not stay on the network for any amount of time, without falling off... I have changed network cards, cables, ports on the switch, etc, and nothing seems to work. I have a Windows 2003 box giving out DHCP addresses, and for a while, i actually tured that off and setup a second Ubuntu box to give IPs... it made no difference. The box gets an IP, and can ping outside for a bit (2 min or so) and then just looses connectivity... ifconfig shows it with an IP (i have tried both Static and DHCP config) and nothing seems to work...

Restarting the network stack (/etc/init.d/networking restart) some times gets a connection working for a few min, but then it falls over again....

Has anyone seen this before? i have tried reinstalling, and it made no difference...

Thanks.

[Update] as requested, here is the output of lshw -C hardware:

    *-network:0 DISABLED    
           description: Ethernet interface
           product: 82546EB Gigabit Ethernet Controller (Copper)
           vendor: Intel Corporation
           physical id: 7
           bus info: pci@0000:02:07.0
           logical name: eth3
           version: 01
           serial: 00:0e:0c:6d:8c:9a
           capacity: 1Gbit/s
           width: 64 bits
           clock: 66MHz
           capabilities: pm pcix msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
           configuration: autonegotiation=on broadcast=yes driver=e1000 driverversion=7.3.21-k8-NAPI firmware=N/A latency=64 link=no mingnt=255 multicast=yes port=twisted pair
           resources: irq:18 memory:ff5a0000-ff5bffff ioport:b800(size=64)
      *-network:1
           description: Ethernet interface
           product: 82546EB Gigabit Ethernet Controller (Copper)
           vendor: Intel Corporation
           physical id: 7.1
           bus info: pci@0000:02:07.1
           logical name: eth2
           version: 01
           serial: 00:0e:0c:6d:8c:9b
           size: 1Gbit/s
           capacity: 1Gbit/s
           width: 64 bits
           clock: 66MHz
           capabilities: pm pcix msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
           configuration: autonegotiation=on broadcast=yes driver=e1000 driverversion=7.3.21-k8-NAPI duplex=full firmware=N/A ip=192.168.0.111 latency=64 link=yes mingnt=255 multicast=yes         port=twisted pair speed=1Gbit/s
           resources: irq:17 memory:ff5c0000-ff5dffff ioport:bc00(size=64)

Just to note, the main onboard network card is not showing up for some reason. I have an Intel Dual GigE PCI card installed. Eth2 is the "Working" interface, an ETH3 is not connected to anything.... Also, this is probably the first time since i installed the machine that the connection is staying up... Do computers regularly fix themselves?

Answer 1

Right... this seems to have fixed itself... Seems that because the eth0 had a static IP, and both eth2 and 3 were dynamic (these are both on a PCI Intel Network card) the onboard card was being listed as "online" even though it had no network cable... Disabling it (ifconfig eth0 down) solved the problem, but once rebooting the machine, the network was gone again. I set eth0 to dhcp in the interfaces config, and now, even after reboot, the machine is keeping its network connection.