Showing posts with label network cards. Show all posts
Showing posts with label network cards. Show all posts

21 August 2012

223. Moving disks, devices from one box to another -- issues with network interfaces

Long story short: edit /etc/udev/rules.d/70-persistent-net.rules

Long story:
I have a very small beowulf cluster keeping my office warm in these antipodean winter months. For some silly reason I was using the front node, a six core + 8 Gb box, as my daily desktop. That of course meant I wasn't really using it for computations. In addition to the front node I have a four core i5-somethingorother with 8 Gb RAM (fast!) and a slovenly AMD X3 /4 Gb to actually run the jobs. They are connected via a gigabit switch ( for nfs exports and a 10/100 router ( for WAN access.

I finally decided that 1) I didn't need a six-core box to prepare latex documents, run octave jobs and make pretty gnuplot plots and that 2) having a slow 3-core AMD box to run heavy nwchem jobs was not fast enough. On the other hand, I didn't want to set up/reinstall/move all my stuff from one harddrive to another.

Linux is wonderful in that it's often just a case of ripping out a harddrive and moving it to a different physical. Windows will scream bloody murder, but linux normally does it pretty well. Same here.

The main issue was the three network cards that I wanted to set up (three separate subnets) and which I configure via /etc/network/interfaces. I simply couldn't call the networks cards what I wanted.

Well, as is obvious in hindsight, you should pay a visit to /etc/udev, and more specifically, /etc/udev/rules.d/70-persistent-net.rules

It looks something like this:

# This file was automatically generated by the /lib/udev/write_net_rules# program, run by the persistent-net-generator.rules rules file.## You can modify it, as long as you keep each rule on a single# line, and change only the value of the NAME= key.
# PCI device 0x10ec:0x8168 (r8169)SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:YY:XX:96:XX:32", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:XX:YY:83:0a:48", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1"SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:XX:YY:64:0b:46", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth2"
# PCI device 0x1814:0x3062 (rt2860)SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="c8:YY:XX:cf:1f:5d", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="ra*", NAME="ra0"
# USB device 0x:0x (rt2800usb)SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="c8:YY:XX:c8:91:e6", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan0"

Basically, make sure you can figure out the mac addresses of the different network cards (ip addr helped me more than ifconfig) you can simply go in and edit the ATTR{address}=="" statements and the NAME="" variables. Make sure that there are no conflicts, obviously.

After that, everything should be fine.

If you are using network-manager (i.e. stock GNOME setup) then you will want to pay attention to the /etc/NetworkManager/system-connections/ as well -- open and edit suspiciously named files like e.g. eth0.

They'll look like this: