Tuesday, 27 November 2012

em1 to ethX on Fedora 17 (how to install matlab if you don't have eth)


I have just moved from Ubuntu 12.04 to Fedora 17. No reason other than necessity for my new job. I'm still happy with Ubuntu and even don't mind Unity!

First thing I wanted to do, of course, was install matlab. It turns out I had a bit of work to do to get it installed on my Dell Precision machine! So here's a post to help out anyone who has the same problem.

If you don't have some eth listed when you ifconfig (I had the NIC listed as em1), matlab will install but you can't activate it. The problem is described on their website  

Basically, Fedora udev names NICs (network cards) embedded on the motherboard as em1, em2 (etc) rather then eth0, eth1 (etc). More details here

The two solutions listed on the Mathworks for changing the names back to eth do not work in my Fedora install. The reason why the first one doesn't work is because there is no /etc/iftab file. the reason why the second one works is because udev rules are not listed in etc (they are in lib instead and have different names and structures)
Thankfully, Fedora has built in a mechanism to modify the names of NICs post install. You do it by editing the following file

/lib/udev/rules.d/71-biosdevname.rules

so the line which reads

GOTO="netdevicename_end"

commented by default, is uncommented

Then you need to edit
/etc/default/grub

by adding the following line to the bottom:

biosdevname=0

Then I backed up my ifcfg em1 network script by issuing

cp /etc/sysconfig/network-scripts/ifcfg-em1 /etc/sysconfig/network-scripts/ifcfg-em1.old

then I renamed it eth0 (the number can be anything, I believe, between 0 and 9, and matlab will figure it out when it activates):

mv /etc/sysconfig/network-scripts/ifcfg-em1 /etc/sysconfig/network-scripts/ifcfg-eth0

and edited ifcfg-eth0 so the line which read

DEVICE="em1"

to read:

DEVICE="eth0"

This is all the information the machine needs, when it boots up, to change the naming convention from em1 back over to eth0.

Upon reboot, ifconfig shows eth0 where em1 was before (dmesg | grep eth would also show the change), and matlab installs perfectly.

A satisfyingly geeky end to a Tuesday!


3 comments:

Emlyn said...

Hey,

I did this by just removing biosdevname. I've started a blog to note what I've done to get fedora stuff to work, it here if you fancy a look:

fixingfedora.blogspot.co.uk/

Emlyn

Daniel Buscombe said...

Wow Emlyn that's a lot more elegant. I shall be following your blog with interest. BTW, what made you move to Fedora?
Dan

陈林曦 said...

Thank you so much! It saved my ass.