CentOS - Feb 2015 - Traditional network interface naming scheme vs. persistent naming

Hi,

I'm currently experimenting with CentOS 7 in order to get a grasp of 
everything that's new.

After having read the FAQ entry on network interface names, I decided to 
revert to the tradictional interface naming scheme by adding the 
relevant kernel options to the bootloader. This went well, I have now 
two interfaces names 'eth0' and 'eth1' as expected.

In my office I have another server with two network interface cards, 
running Slackware64 14.1. On a stock Slackware installation, as soon as 
there is more than one NIC, the system creates a file 
/etc/udev/rules.d/70-persistent-net.rules, which looks like this:

  # PCI device 0x8086:/sys/devices/pci0000:00/0000:00:02.0/0000:02:00.0 
(e1000e)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", 
ATTR{address}=="2c:27:d7:15:54:a1", ATTR{dev_id}=="0x0", 
ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

# PCI device 0x8086:/sys/devices/pci0000:00/0000:00:04.0/0000:03:00.0 
(e1000e)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", 
ATTR{address}=="00:22:64:8a:4c:c2", ATTR{dev_id}=="0x0", 
ATTR{type}=="1", KERNEL=="eth*", NAME="eth1"

Usually I have a 50 % chance of getting the network interface right 
(well, according to Murphy, I have more like a 100 % chance of getting 
it wrong the first time :oD). In that case, I simple edit the 
70-persistent-net.rules file, permutate the "eth0" and
"eth1" entries
and then reboot.

How would I go about that under CentOS with traditional interface names? 
The 70-persistent-net.rules file doesn't exist. Do I have to create it 
from scratch?

Cheers,

Niki Kovacs
-- 
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Web  : http://www.microlinux.fr
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T?l. : 04 66 63 10 32

On 02/04/15 22:53, Niki Kovacs wrote:
> Hi,
>
> I'm currently experimenting with CentOS 7 in order to get a grasp of 
> everything that's new.
>
> After having read the FAQ entry on network interface names, I decided 
> to revert to the tradictional interface naming scheme by adding the 
> relevant kernel options to the bootloader. This went well, I have now 
> two interfaces names 'eth0' and 'eth1' as expected.
>
> In my office I have another server with two network interface cards, 
> running Slackware64 14.1. On a stock Slackware installation, as soon 
> as there is more than one NIC, the system creates a file 
> /etc/udev/rules.d/70-persistent-net.rules, which looks like this:
>
>  # PCI device 0x8086:/sys/devices/pci0000:00/0000:00:02.0/0000:02:00.0 
> (e1000e)
> SUBSYSTEM=="net", ACTION=="add",
DRIVERS=="?*",
> ATTR{address}=="2c:27:d7:15:54:a1",
ATTR{dev_id}=="0x0",
> ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"
>
> # PCI device 0x8086:/sys/devices/pci0000:00/0000:00:04.0/0000:03:00.0 
> (e1000e)
> SUBSYSTEM=="net", ACTION=="add",
DRIVERS=="?*",
> ATTR{address}=="00:22:64:8a:4c:c2",
ATTR{dev_id}=="0x0",
> ATTR{type}=="1", KERNEL=="eth*", NAME="eth1"
>
> Usually I have a 50 % chance of getting the network interface right 
> (well, according to Murphy, I have more like a 100 % chance of getting 
> it wrong the first time :oD). In that case, I simple edit the 
> 70-persistent-net.rules file, permutate the "eth0" and
"eth1" entries
> and then reboot.
>
> How would I go about that under CentOS with traditional interface 
> names? The 70-persistent-net.rules file doesn't exist. Do I have to 
> create it from scratch?
>
> Cheers,
>
> Niki Kovacs
Those are udev rules (which's now integrated with systemd in CentOS 7).

You don't have to create a new one, but you have to find the one. I 
suggest reading up on the udev rules file.

On Wed, Feb 4, 2015 at 11:23 AM, Niki Kovacs <info at microlinux.fr>
wrote:
> Hi,
>
> I'm currently experimenting with CentOS 7 in order to get a grasp of
> everything that's new.
>
> After having read the FAQ entry on network interface names, I decided to
> revert to the tradictional interface naming scheme by adding the relevant
> kernel options to the bootloader. This went well, I have now two interfaces
> names 'eth0' and 'eth1' as expected.
>
> In my office I have another server with two network interface cards,
running
> Slackware64 14.1. On a stock Slackware installation, as soon as there is
> more than one NIC, the system creates a file
> /etc/udev/rules.d/70-persistent-net.rules, which looks like this:
>
>  # PCI device 0x8086:/sys/devices/pci0000:00/0000:00:02.0/0000:02:00.0
> (e1000e)
> SUBSYSTEM=="net", ACTION=="add",
DRIVERS=="?*",
> ATTR{address}=="2c:27:d7:15:54:a1",
ATTR{dev_id}=="0x0", ATTR{type}=="1",
> KERNEL=="eth*", NAME="eth0"
>
> # PCI device 0x8086:/sys/devices/pci0000:00/0000:00:04.0/0000:03:00.0
> (e1000e)
> SUBSYSTEM=="net", ACTION=="add",
DRIVERS=="?*",
> ATTR{address}=="00:22:64:8a:4c:c2",
ATTR{dev_id}=="0x0", ATTR{type}=="1",
> KERNEL=="eth*", NAME="eth1"
>
> Usually I have a 50 % chance of getting the network interface right (well,
> according to Murphy, I have more like a 100 % chance of getting it wrong
the
> first time :oD). In that case, I simple edit the 70-persistent-net.rules
> file, permutate the "eth0" and "eth1" entries and then
reboot.
>
> How would I go about that under CentOS with traditional interface names?
The
> 70-persistent-net.rules file doesn't exist. Do I have to create it from
> scratch?
>
Probably more than you want to know about this weirdness and the
multiple ways of doing it:

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/pdf/Networking_Guide/Red_Hat_Enterprise_Linux-7-Networking_Guide-en-US.pdf

-- 
  Les Mikesell
    lesmikesell at gmail.com