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Old 11-03-2006, 08:38 AM   #1
Registered: Aug 2006
Location: Nottingham
Distribution: Fedora
Posts: 86

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ifconfig eth0 mac address update won't allow me to connect to internet

Hi all,

I have worked out why I couldn't connect to NTL with my laptop. It was because my mac address wasn't registered with them.

I now have another problem (which is actually the same problem)that my internet connection still won't connect.

I updated my mac address with the following commands:

/sbin/ifconfig eth0 down hw ether **:**:**:**:**:**
/sbin/ifconfig eth0 up

I then activated the network connection with system-config-network

I then typed /sbin/ifconfig eth0 to get the following:

eth0 Link encap:Ethernet HWaddr **:**:**:**:**:**
inet addr:**.**.**.*** Bcast: Mask:
inet6 addr: ****::***:****:****:****/** Scope:Link
RX packets:1 errors:0 dropped:0 overruns:0 frame:0
TX packets:43 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:342 (342.0 b) TX bytes:7247 (7.0 KiB)
Interrupt:17 Base address:0xa400

This tells me that it went and got the IP and checking in system-config-network tells me that the connection is active.

The problem is that even though it says the connection is active I still can't seem to get on the net.

I pinged a machine that I know is always on line but to no avail.

The other problem is that when I reboot my machine it automatically loses the mac address that I updated.

Any help that could be rendered would be most helpful as I am at a complete loss on how to proceed.

Thanks in advance.


Last edited by mike_morley; 11-03-2006 at 09:37 AM.
Old 11-03-2006, 10:12 AM   #2
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Registered: Nov 2002
Location: Somewhere inside 9.9 million sq. km. Canada
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One way to update your MAC address so it doesn't get lost is to install WebMin. You can then edit the MAC IP addresses etc, save them so next boot they are not lost. You can also remotley manage a bunch of stuff with WebMin.

It appears you edited out the IP address from the ifconfig output. Does the IP address you got make sense for the network you are connecting to? If yes, have you got DNS addresses in /etc/resolv.conf? If not, that is probably why you can not "connect".

BTW, what is 'NTL' ??? When you are half way around the world...
Old 11-03-2006, 02:32 PM   #3
Registered: Aug 2006
Location: Nottingham
Distribution: Fedora
Posts: 86

Original Poster
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Thanks Camorri.

The IP address is correct for the network and the DNS servers are listed in resolv.conf

NTL is an ISP, come cable, come telephone company

Thanks for the tip about webmin but is there a manual way of doing this so I can learn how to edit my own start up?
Old 11-03-2006, 03:09 PM   #4
Registered: Aug 2006
Location: Nottingham
Distribution: Fedora
Posts: 86

Original Poster
Rep: Reputation: 15

And for as a first it wasn't anything I was doing wrong.

Because I tried to connect with an incorrect mac address from my laptop multiple times and then attempted again after a couple of seconds with the correct mac address I must have been locked out of my ISP for a short time.

I found this out because after I tried to connect with my laptop, I plugged my PC back in (which was working) and found that I could no longer connect to the net.

It was at this point I unplugged the power from my cable modem and went down the gym for a couple of hours. When I got back I tried my PC again and found that it was working again.

I then plugged the network cable back into my laptop and went through the process of changing my mac address again. I reactivated my network device through system-config-network and found that low and behold I could connect to the net and post the solution on LQ.

I hope this solution is helpful for someone else out there who is having similar problems.

Thanks for the help Camorri.

Last edited by mike_morley; 11-05-2006 at 10:51 AM.
Old 11-03-2006, 06:08 PM   #5
Registered: Jun 2001
Location: UK
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Yeah NTL caches MAC's on DHCP for about 4 hours normally, piss them off and you get locked out for a while. NTL's customer services bite ass, but getting online with them is so painfully easy compared to PSTN ADSL providers.


connection, fc5, ifconfig, mac, network

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