My hardware MAC address is always 00:00:00:00:00:00 until I manually update 'eth0'. How can I fix this?

12.04 networking ethernet

6,709

Could you clarify exactly what you mean when you say that your MAC is 00:00:00:00:00:00.

What happens when you open the menu for Unity's Network Indicator, select Edit Connections, and then click on the Edit button for the Wired connection?

Do you see 00:00:00:00:00:00 as the only possible value for Device MAC address? (See example in the third (last) screenshot below.)

screenshot of Network Indicator's menu

screenshot of Network Connections settings window

screenshot of edit window for Wired connection settings

For whatever it is worth, the contents of my NetworkManager.conf file differs from yours. I do not have the entry no-auto-default=00:00:00:00:00:00,.

[main]
plugins=ifupdown,keyfile
dns=dnsmasq

[ifupdown]
managed=false

Below is an excerpt from the online documentation for the NetworkManager configuration file describing no-auto-default.

Set devices for which NetworkManager shouldn't create default wired connection (Auto eth0). NetworkManager creates a default wired connection for any wired device that is managed and doesn't have a connection configured. List a device in this option to inhibit creating the default connection for the device.

I am not sure that the no-auto-default entry is the cause of your problem. But you could still try the following just to rule it out.

Create a backup copy of the file. One way to do this would be by using the copy command below.
```
cd /etc/NetworkManager
sudo cp NetworkManager.conf NetworkManager.conf.backup
```
Use a text editor, for example gedit, to edit NetworkManager.conf and delete the no-auto-default line to see if it makes a difference.
```
sudo gedit /etc/NetworkManager/NetworkManager.conf
```

6,709

user57184

Updated on September 18, 2022

Comments

user57184 over 1 year
I am using Ubuntu 12.04. I use a wired connection. My network MAC address shows as 00:00:00:00:00:00.

When I enter the commands below into a terminal window, it starts working again.
```
sudo ifconfig eth0 down
sudo ifconfig eth0 hw ether my mac address
sudo ifconfig eth0 up
```
I have to enter these commands every time I want to use the Internet. How can I fix this?

Update copied from comment

The contents of my /etc/NetworkManager/NetworkManager.conf file is:
```
[main] 
plugins=ifupdown,keyfile 
dns=dnsmasq 
no-auto-default=00:00:00:00:00:00,

[ifupdown] 
managed=false
```
- Mitch almost 12 years
  
  Take a look at this askubuntu.com/questions/74575/…
- user57184 almost 12 years
  
  I know my Mac address. When I put it in network connections nothing happens. I think that some bug has made 00:00:00:00:00:00 my default mac address.
user57184 almost 12 years

I am new to ubuntu. Networkmanager conf file in etc/networkmanager is like this [main] plugins=ifupdown,keyfile dns=dnsmasq no-auto-default=00:00:00:00:00:00, [ifupdown] managed=false I can type my mac address in network connections. When I save it nothing happens. It shows 00:00:00:00:00:00 as an option and when I click on it save option gets disabled.
irrational John almost 12 years

@user57184 Would you please verify that using the GUI configuation windows give you the same results. If any changes were made, the GUI should almost certainly have been updated to work correctly since that would be considered to be the way most people would change their settings.
user57184 almost 12 years

How to create a back up copy of Networkmanager.conf?
nilsonneto almost 12 years

@irrationalJohn - please remove the questions in your answer. Remember to use comments to ask for further details.
nilsonneto almost 12 years

@user57184 - this is a Q&A site. Please keep editing your question with important information such as the above - comments is not the best please for this type of info. Thanks.
irrational John almost 12 years

@fossfreedom If you would show me how I can fit the question I asked, complete with screenshots, into a comment then I will do this. Comments work for some things. Other questions IMO require more detail to clarify what is being asked. I do not know of any way to do the latter in a comment.
irrational John almost 12 years

@user57184 Could you please add the output from the command ifconfig -a -v to your question? (You will have to edit your question to do this. It won't fit or format in a comment. Besides, as fossfreedom pointed out, extra details are best added by editing your question. See also this faq.)
irrational John almost 12 years

@user57184 Updated my answer again. Added cp to backup file.
irrational John almost 12 years

@user57184 Is the correct MAC address shown in output from sudo lshw -C network? (It would be listed after serial:)