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  1. #1

    Help! No IPv4 on eth0 = no connect to router

    I have tried clean installs of Knoppix v0.6, Xandros 2.0, and Ubuntu 7.1... same issue with all. I cannot seem to get eth0 (via chip on mobo) to get/have/use IPv4. ifconfig shows only IPv6.

    (I cannot paste any info because linux desktop is on different box.)

    End result is that I cannot get the linux desktop to connect to my lan, either with dhcp or with static ip.

    I have a belkin router configured as my gateway and nothing fancy with the setup. I have dhcp open for thru ...254 and at most there are only 4 systems in home connecting with dhcp at any time. all other systems have static addresses.

    I have two decades of desktop and lan support under my belt, but relatively small amount of command line experience and almost no history with linux (unless you count a dozen unsuccessful attempts to burn linux distro install discs on this Vista desktop).

    Therein lies the start of my prob. I need to build and manage a fileserver for my home, but cannot seem to get a working installer cd or dvd to burn from anything I download.

    So I said to myself, "Self," I said, "you're a tech. Build a workstaion, use the DVD that came with your Linux Bible (2008 Ed.) to install one of the linux distros on it, then download a recent, stable server distro and burn it using the linux workstation."

    Unfortunately, if I cant get an ipv4 connection to my home network, I cant get out to the Internet to download any newer ISO files.

    So what am I missing or doing wrong? How do I tell linux to stop trying to use IPv6 and let me use IPv4?

    BTW, eth0 works just fine if I install Windows on that PC, so I know its not bad HW. Could it be a driver issue? Or do I need to use some Terminal command to turn off IPv6 and reconfigure eth0 for IPv4?

  2. #2
    Just Joined! its_really_me's Avatar
    Join Date
    Mar 2010

    it could well be a driver issue. I had the same once with an USB to Ethernet adapter. It was recognized but no traffic going through.

    You have not added much details what you've tried already, so this list may sound a little basic. But as you write that you have almost no experience with the shell, I try anyways.

    I assume you checked ifconfig eth0 and you only see the IPv6 address. That may be because IPv6 is assigned as logocl link address using it's own MAC address. Can you confirm that the MAC address listed in ifconfig is correct? Also, what happens if you enter ifconfig eth0 up?
    (you may need to use sudo)
    There are usually some network scripts somehwere, i.e. /etc/sysconfig/netwoork-scripts/ifcfg-eth0. Can you check the content? The location might be different on your system but somewhere below /etc I guess.
    Do you know the chipset of the Ethernet port, maybe from your Windows OS? Maybe you need to add a driver for it.
    check with tcpdump -i eth0 if some packets are sent/received. If you do not see anything for a while, disconnect the cable and reseat it. DHCP packets should flow now.
    I can help further when you provide some of the info...

    Ah, and what is the current distro you are running?

  3. #3
    Thanks for the assist.

    Windows drivers were all up to date. Wasn't sure if maybe I needed to do same with Linux drivers. (This is not a dual-boot system - I had completely replaced the WinXP 40GB hdd with a 3.2GB hdd for the Linux install. If must be done, I can put the WinXP drive back in, but would rather try to resolve without additional stress on HW and cables.)

    What I've tried:
    Besides clean installs of multiple distros, I have run "ifconfig" (and yes, all that produces is IPv6 and Loopback data), and I have tried to PING my router. Outdaide of Terminal, I have attempted to reach router via theweb-page access, but get message that "access has been refused." I have also triedreconfiguring eth0, in Network Configuration (GUI admin tool) and creating new eth0 profile with different name.

    Dont think I have an easy way to confirm mac address.

    Please explain what you mean by the phrase, "enter ifconfig eth0 up."

    I will explore /etc for any network scripts I can find.

    I will obtain precise manufacture info from the hardware profile in device manager.

    Tons of packets have been sent throughout all of this.. all have failed.

    Cable has been not only reseated, but changed out, too.

    Current distro is Ubuntu 7.10. (That's what came on the dvd in my 2008 Edition of Linux Bible, by Christopher Negus.)

    I will attempt to copy & paste as much data as I can obtain from today's research into a text file and bring it over to the Vista box on a thumb drive.

    Thank you again. At least I now have a somewhat more focused direction than what I had yesterday. Perhaps by tonight I will be a bit closer to goal. = )

  4. $spacer_open
  5. #4
    Linux Guru reed9's Avatar
    Join Date
    Feb 2009
    Boston, MA
    Normally, after attempting ipv6 and failing, it should gracefully degrade to using ipv4. I've not seen reports of it failing to acquire an ip address or connect at all because of ipv6. Odd. I wonder if blacklisting the module will help.

    I think in 7.10, there should be a file /etc/modprobe.d/aliases. Check that for a line
    alias net-pf-10 ipv6
    Change to
    alias net-pf-10 off
    You'll need to open a text editor as root to do so. I like the command line text editor nano.
    sudo nano /etc/modrobe.d/aliases
    Or you can do it the geeky way with sed
    sudo sed -i -e 's/alias net-pf-10 ipv6/#&\nalias net-pf-10 off/' /etc/modprobe.d/aliases
    If that file isn't there, it's fine. Continue with blacklisting the module.
    echo "blacklist ipv6" | sudo tee -a /etc/modprobe.d/blacklist.conf
    If you find the module is ornery and still loads, get firm with it and send it off to the black hole of /bin/true
    echo "install ipv6 /bin/true" | sudo tee -a /etc/modprobe.d/blacklist.conf
    This means anytime something tries to load the module, it installs to /bin/true, which sends it off to nowhere and returns a true value.

  6. #5

    Thanks to all who assisted!

    I don't know what happened between last night's shut down and today's power-up, but everything is working great now. Below is data copied from Terminal, just as a FYI. Now that I can connect to Internet, I will be downloading the latest stable versions of both, Ubuntu desktop and server.

    toby@Peregrine:~$ ifconfig
    eth0 Link encap:Ethernet HWaddr 00:0D:87:52:E5:A6
    inet addr: Bcast: Mask:
    inet6 addr: fe80::20d:87ff:fe52:e5a6/64 Scope:Link
    RX packets:117 errors:0 dropped:0 overruns:0 frame:0
    TX packets:118 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:1000
    RX bytes:56896 (55.5 KB) TX bytes:11298 (11.0 KB)
    Interrupt:11 Base address:0xe800

    lo Link encap:Local Loopback
    inet addr: Mask:
    inet6 addr: ::1/128 Scope:Host
    UP LOOPBACK RUNNING MTU:16436 Metric:1
    RX packets:0 errors:0 dropped:0 overruns:0 frame:0
    TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:0
    RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

    toby@Peregrine:~$ ping
    PING ( 56(84) bytes of data.
    64 bytes from icmp_seq=1 ttl=64 time=0.972 ms
    64 bytes from icmp_seq=2 ttl=64 time=0.674 ms
    64 bytes from icmp_seq=3 ttl=64 time=0.678 ms
    64 bytes from icmp_seq=4 ttl=64 time=0.664 ms
    64 bytes from icmp_seq=5 ttl=64 time=0.666 ms

    [1]+ Stopped ping

    ************************************************** **************

    Successful access to router!
    Successful Ubuntu home-page!

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