Most recent edit on 2008-03-16 15:14:17 by FreekDijkstra

Additions:
Another rule I've seen is:

SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:16:3e:00:02:00", NAME="eth0"
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:16:3e:00:02:01", NAME="eth1"

I'm not sure about the difference between these rules. Information is welcome (please leave a comment below)

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Edited on 2007-09-27 14:43:07 by FreekDijkstra

Additions:
The udev method should work on all recent Linux distributions, and is recommended. The get-mac-address.sh script and the nameif program are know to work with Debian, while on Red Hat, you can change the interface configuration file.

Using the interface configuration file

If you run a Red-Hat-based distribution, you can simply add the MAC addres in the interface configuration file /etc/sysconfig/network-scripts/ifcfg-eth0:

DEVICE=eth0
HWADDR=00:37:e9:17:64:af

You can give it any DEVICE name you want, like DEVICE=ethmgmt, as long as you remember to rename the config file:
/etc/sysconfig/network-scripts/ifcfg-ethmgmt
Source: http://forums.serverwatch.com/showthread.php?t=18476∞

Deletions:
The udev method should work on all recent Linux distributions, and is recommended. The get-mac-address.sh script and the nameif program are know to work with Debian. Other distributions to not have the interface file , but other mechanisms for interface configuration (like /etc/sysconfig/network-scripts/ files for Red Hat). So, it may not be trivial to apply this to other distributions. However, if you succeed, we very much welcome feedback!

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Edited on 2007-09-27 14:30:41 by FreekDijkstra

Additions:
Another solution is to use the get-mac-address.sh script to map interface names by MAC address. On Debian, this script is distributed as part of the ifupdown package∞ (in /usr/share/doc/ifupdown/examples/get-mac-address.sh). Copy this script to a saner place (e.g. /usr/local/bin), and you can setup /etc/network/interfaces in this manner:
Alternative to the get-mac-address.sh script, you can also use the slightly more convenient nameif program, which is distributed as part of the net-tools package∞ on Debian.
It is not possible to rename an interface to a name of an existing interface. So you can't rename eth1 to eth0 as long as eth0 still exists. It is possible to still swap the names eth0 and eth1 by using a temporary name (e.g. first rename eth1 to ethfoo, then eth0 to eth1 and finally ethfoo to eth0). Note that this method may lead to problems if you use common names such as eth0 and eth1. If you upgrade a kernel, the names may be different than you expected, and you may rename a NIC to eth0 while eth0 still exists, leading to name collisions. Therefor, it is recommended to use other names like "ethmgmnt", "ethwired", "ethwireless" and "eth10ge", as shown in the example above.

Deletions:
The first solution is to use the get-mac-address.sh script to do mapping by MAC address. On Debian, this script is distributed as part of the ifupdown package∞ (in /usr/share/doc/ifupdown/examples/get-mac-address.sh). With this script copied to some sane place (e.g. /usr/local/bin), you can then setup /etc/network/interfaces in this manner:
Alternative to the get-mac-address.sh script, you can also use the slightly more convienant nameif program, which is distributed as part of the net-tools package∞ on Debian.
It is not possible to rename an interface to a name of an existing interface. So you can't rename eth1 to eth0 as long as eth0 still exists. It is possible to still swap the names eth0 and eth1 by using a temporary name (e.g. first rename eth1 to ethfoo, then eth0 to eth1 and finally ethfoo to eth0). It should be noted however, that this may lead to problems if you add another network cards or upgrade your kernel, and the interface names just before you call nameif are not as expected. Therefor, it is recommended to use other names like "ethmgmnt", "ethwired", "ethwireless" and "eth10ge", as shown in the example above.

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Edited on 2007-09-27 14:20:42 by FreekDijkstra

Additions:
Now that you have udev, it is rather simple. You only need to create a udev rule mapping the MAC address to the interface name. Store this in a file inside the /etc/udev/rules.d/ directory:
Written by Freek Dijkstra. Licensed under public domain. (That is, feel free to modify, redistribute, cripple, or even sell it as your own work, and there is no need to mention the source, even though you are of course welcome to do so.)

Deletions:
Now that you have udev, it rather simple. You only need to create a udev rule mapping the MAC address to the interface name. Store this in a file inside the /etc/udev/rules.d/ directory:
Written by Freek Dijkstra. Licensed under public domain. (That is, feel free to re-use it, and there is no need to mention the source, even though you are of course welcome to do so.)

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Edited on 2007-09-27 14:17:20 by FreekDijkstra

Additions:
The disadvantage of ethtool is that it can only be run by root, even when you're only using it to query for information. Though this is a minor annoyance of ethtool, it doesn't matter in this case, since you want to set a device name and thus need to be root anyway.
There are three ways to map the MAC address to the logical interface name. Either by using the udev rules, with the get-mac-address.sh script, or by using the nameif program.
The udev method should work on all recent Linux distributions, and is recommended. The get-mac-address.sh script and the nameif program are know to work with Debian. Other distributions to not have the interface file , but other mechanisms for interface configuration (like /etc/sysconfig/network-scripts/ files for Red Hat). So, it may not be trivial to apply this to other distributions. However, if you succeed, we very much welcome feedback!

Deletions:
The disadvantage of ethtool is that it can only be run by root, even when you're only using it to query for information. Though this is a minor annoyance of ethtool, it doesn't matter in this case, since you have to be root to set a device name anyway.
There are three ways to do map the MAC address to the logical interface name. Either by using the udev rules, by the get-mac-address.sh script, or by using the nameif program.
The udev method should work on all distributions, and is recommended. The get-mac-address.sh script and the nameif program are know to work with Debian. Other distributions to not have the interface file , but other mechanisms for interface configuration (like /etc/sysconfig/network-scripts/ files for Red Hat). So, it may not be trivial to apply this to other distributions. However, if you succeed, we very much welcome feedback!

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Edited on 2007-09-27 14:13:33 by FreekDijkstra

Additions:
So you have to pick a method that suits you. I recommend either to use ifrename (based on physcial properties, especially useful if you often change network cards in your hosts) or writing a udev rule (based on the MAC address). However, I listed the other methods as well. Be aware that the last two methods mentioned in this article are only for the masochistic (you will scream and shoot to get those to work).

Deletions:
So you have to pick a method that suits you. I recommend either to use ifrename (based on physcial properties, especially useful if you often change network cards in your hosts) or writing a udev rule (based on the MAC address). However, I listed the other methods as well. Be aware that the last two methods mentioned in this article are only for the masochistic (you will scream and shoot to get it to work).

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Edited on 2007-09-27 14:13:15 by FreekDijkstra

Additions:
So you have to pick a method that suits you. I recommend either to use ifrename (based on physcial properties, especially useful if you often change network cards in your hosts) or writing a udev rule (based on the MAC address). However, I listed the other methods as well. Be aware that the last two methods mentioned in this article are only for the masochistic (you will scream and shoot to get it to work).

Deletions:
So you have to pick a method that suits you. I recommend either to use ifrename (baed on physcial properties, especially useful if you often change network cards in your hosts) or writing a udev rule (based on the MAC address). However, I listed the other methods as well. Be aware that the last two methods mentioned in this article are only for the masochistic.

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Edited on 2007-09-27 14:12:23 by FreekDijkstra

Additions:
1. Order the network interfaces based on physical properties of the NIC. (e.g. the physical location in the machine)

Deletions:
1. Order the network interfaces based on physical properties of the NIC. (e.g. the

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Edited on 2007-09-27 14:11:39 by FreekDijkstra

Additions:
Obviously there is some logic to which network interface gets which name, but Linux documentation states that this may change and no user or program should ever assume anything about this. This is annoying, in particular if your management interface is at eth1 at one node in a cluster and at eth2 in another node of the same cluster (which we have experienced). I personally like to have my (primary) management interface always to be eth0.

Deletions:
Obviously there is some logic to which network interface gets which name, but Linux documentation states that this may change and no user or program should ever assume anything about this. Obviously, this is annoying, in particular if your management interface is at eth1 at one node in a cluster and at eth2 in another node of the same cluster (which we have experienced). I personally like to have my (primary) management interface always to be eth0.

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Edited on 2007-01-03 10:41:11 by FreekDijkstra

Additions:
One of the problems of Linux is that the order of the network interfaces is unpredictable. Between reboots it usually stays the same, but often after an upgrade to a new kernel or the addition or replacement of a network card (NIC) the order of all network interfaces changes. For example, what used to be eth0 now becomes eth1 or eth2 or visa versa.
So you have to pick a method that suits you. I recommend either to use ifrename (baed on physcial properties, especially useful if you often change network cards in your hosts) or writing a udev rule (based on the MAC address). However, I listed the other methods as well. Be aware that the last two methods mentioned in this article are only for the masochistic.

Deletions:
One of the problems of Linux is that the order of the network interfaces is unpredictable. Between reboots it does stay the same, but it is very well possible that after an upgrade to a new kernel or the addition or replacement of a network card (NIC) that the other of all network interface changes. For example, what used to be eth0 now becomes eth1 or eth2 or visa versa.
So you have to pick a method that suits you. I recommend either to use ifrename (baed on physcial properties) or writing a udev rule (based on the MAC address). However, I listed the other methods as well. Be aware that the last two methods mentioned in this article are only for the masochistic.

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Edited on 2007-01-03 10:36:59 by FreekDijkstra

Additions:

KERNEL=="eth?", SYSFS{address}=="00:37:e9:17:64:af", NAME="eth0"  # MAC of first NIC in lowercase
KERNEL=="eth?", SYSFS{address}=="00:21:e9:17:64:b5", NAME="eth1"  # MAC of second NIC in lowercase

Deletions:

KERNEL=="eth?", SYSFS{address}=="MAC of first NIC", NAME="eth0"
KERNEL=="eth?", SYSFS{address}=="MAC of second NIC", NAME="eth1"

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Edited on 2007-01-03 10:33:59 by FreekDijkstra

Additions:
Obviously there is some logic to which network interface gets which name, but Linux documentation states that this may change and no user or program should ever assume anything about this. Obviously, this is annoying, in particular if your management interface is at eth1 at one node in a cluster and at eth2 in another node of the same cluster (which we have experienced). I personally like to have my (primary) management interface always to be eth0.

1. Order the network interfaces based on physical properties of the NIC. (e.g. the

So you have to pick a method that suits you. I recommend either to use ifrename (baed on physcial properties) or writing a udev rule (based on the MAC address). However, I listed the other methods as well. Be aware that the last two methods mentioned in this article are only for the masochistic.
Ifrename is a tool specifically designed to (re)name network interfaces based on characteristics like MAC address (wildcards supported), bus information, and hardware settings. It uses a control file (/etc/iftab) to specify rules about how the interfaces will be named. (thanks to Matt Baron for this tip.)
First, you must determine the MAC address of your interfaces. You can do this locally on a machine running

ifconfig -a

There are three ways to do map the MAC address to the logical interface name. Either by using the udev rules, by the get-mac-address.sh script, or by using the nameif program.
The udev method should work on all distributions, and is recommended. The get-mac-address.sh script and the nameif program are know to work with Debian. Other distributions to not have the interface file , but other mechanisms for interface configuration (like /etc/sysconfig/network-scripts/ files for Red Hat). So, it may not be trivial to apply this to other distributions. However, if you succeed, we very much welcome feedback!

Using udev rules

udev replaced devfs in Linux 2.6. First make sure that your Linux system has udev installed, rather then devfs. If you have a /etc/udev directory, but not /etc/devfs directory, you are probably fine. If not, be aware that changing your kernel from devfs to udev is possible, but is not just a matter of adding a new module. Perhaps for now, another method is easier for you.
Now that you have udev, it rather simple. You only need to create a udev rule mapping the MAC address to the interface name. Store this in a file inside the /etc/udev/rules.d/ directory:

KERNEL=="eth?", SYSFS{address}=="MAC of first NIC", NAME="eth0"
KERNEL=="eth?", SYSFS{address}=="MAC of second NIC", NAME="eth1"

Most distibutions already come with an example config file for you. E.g. /etc/udev/rules.d/network-devices.rules or /etc/udev/rules.d/010_netinterfaces.rules. More information can be found at http://www.reactivated.net/writing_udev_rules.html∞ or http://www.debianhelp.co.uk/udev.htm∞. (Thanks to Casey Scott and Ron Hermsen for the pointers.)
Next, update /etc/modules.conf by running:

Deletions:
Obviously there is some logic to which network interface gets which name, but Linux documentation states that this may change and no user or program should ever assume anything about this. Obviously, this is annoying, in particular if your management interface is at eth1 at one node in a cluster and at eth2 in another node of the same cluster (which we have experienced). I personally like to have my (primary) mangement interface always to be at eth0.

1. Order the network interfaces based on physical properties of the NIC.

Ifrename is a tool specifically desgined to (re)name network interfaces based on characteristics like MAC address (wildcards supported), bus information, and hardware settings. It uses a control file (/etc/iftab) to specify rules about how the interfaces will be named. (thanks to Matt Baron for this tip.)
As a first start, you must determine the MAC address of your interfaces. You can do this locally on a machine using

ifconfig -a

There are two ways to do map the MAC address to the logical interface name. Either by using the get-mac-address.sh script, or by using the nameif program. The method bellow is know to work with Debian. Other distributions to not have the interface file , but other mechanisms for interface configuration (like /etc/sysconfig/network-scripts/ files for Red Hat). So, it may not be trivial to apply this to other distributions. However, if you succeed, we very much welcome feedback!
Next, update //etc/modules.conf by running:

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Edited on 2006-01-05 22:48:19 by FreekDijkstra

Additions:

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Written by Freek Dijkstra. Licensed under public domain. (That is, feel free to re-use it, and there is no need to mention the source, even though you are of course welcome to do so.)

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Edited on 2006-01-05 22:46:35 by FreekDijkstra

Additions:
Secondly, it is also possible to name the network interface based on the MAC address of each NIC. The advantage is that it is possible to use this method if you have two NICs which use the same driver (unlike the next method: based on driver).
The disadvantage of this method is that defines a mapping, rather then changing the actual logical interface name.
This is a relative easy method, since it does not rely on external scripts. The idea is to just load the kernel module for your eth0 interface before the modules for other network cards.

Deletions:
Secondly, it is also possible to name the network interface based on the MAC address of each NIC. The advantage is that it is possible to use this method if you have two NICs which use the same driver.
The disadvantage of this method is that does define a mapping, rather then changing the actual logical interface name.

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Edited on 2006-01-05 22:38:32 by FreekDijkstra

Additions:

How to reorder or rename logical interface names in Linux

Deletions:

How to reorder or rename logical interfaces names in Linux

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Edited on 2006-01-05 22:37:23 by FreekDijkstra

Additions:
Secondly, it is also possible to name the network interface based on the MAC address of each NIC. The advantage is that it is possible to use this method if you have two NICs which use the same driver. Warning: This only works if the driver is available as a loadable module. Not if it is built into the kernel.
First of all, you must determine which driver is used for each network card. Thankfully Linux does have a system to load the appropriate driver automatically, based on the PCI ID∞ of the network card. Unfortunately, there is no single command to simply get the driver (and other information like the link speed) based on just the interface name in Linux. Your best bet is to look for kernel messages:
This should give you a good estimate of the driver name. You can verify if the name indeed does exist and is loaded:

Deletions:
Last, it is also possible to name the network interface based on the MAC address of each NIC. The advantage is that it is possible to use this method if you have two NICs which use the same driver.
Warning: This only works if the driver is not built into the kernel, but is available as a loadable module.
First of all, determine which driver is used by each network card. Thankfully Linux does have a system to load the appropriate driver automatically, based on the PCI ID∞ of the network card. Unfortunately, there is no single command to simply get the driver (and other information like the link speed) based on just the interface name in Linux. Your best bet is to look for kernel messages:
This should give you a good estimate of the driver name. You can further verify if the name you have in mind indeed does exist and is loaded:

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Edited on 2006-01-05 22:33:07 by FreekDijkstra [Information about ifrename]

Additions:
1. Order the network interfaces based on physical properties of the NIC.

2. Order the network interfaces based on the MAC address of the NIC.
3. Order the network interfaces based on the driver of the NIC.
4. Order the network interfaces based on the physical location of the NIC in the computer

Using the ifrename tool

Ifrename is a tool specifically desgined to (re)name network interfaces based on characteristics like MAC address (wildcards supported), bus information, and hardware settings. It uses a control file (/etc/iftab) to specify rules about how the interfaces will be named. (thanks to Matt Baron for this tip.)
# Example /etc/iftab file
eth2 mac 08:00:09:DE:82:0E
eth3 driver wavelan interrupt 15 baseaddress 0x390
eth4 driver pcnet32 businfo 0000:02:05.0
# wildcard name: pick the lowest available name of air0, air1, air2, etc.
air* mac 00:07:0E:* arp 1
The disadvantage of ethtool is that it can only be run by root, even when you're only using it to query for information. Though this is a minor annoyance of ethtool, it doesn't matter in this case, since you have to be root to set a device name anyway.
Note: It is relatively hard to get this to work, and we encountered problems with it. The other methods are recommended.

Deletions:
1. Order the network interfaces based on the physical location of the NIC in the computer

2. Order the network interfaces based on the driver of the NIC.
3. Order the network interfaces based on the MAC address of the NIC.
4. Order the network interfaces based on physical properties of the NIC.

Note: It is relatively hard to get this to work, and we encountered problems with it. |the other methods are recommended.

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Edited on 2005-07-06 09:09:08 by FreekDijkstra

Deletions:
Note: I haven't checked if it ethtool and ip do work properly if an interface is down. This is important because they should be renamed before the system brings them up (since the configuration is based on the name of the interface).

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Edited on 2005-07-06 09:04:06 by FreekDijkstra [added a fourth method]

Additions:
Thankfully, there are ways to achieve this. They can be divided in four methods:

4. Order the network interfaces based on physical properties of the NIC.

Based on the physical properties

Perhaps the most elegant way to name the ethernet NIC is to do so based on their physical properties, like link speed and port type.

Using the ethtool and ip programs

It is possible to check the NIC properties using the ethtool program, and to change the name using the ip program (thanks to Jollynn Schmidt for this tip):

if ethtool eth0 | grep -q "Port: FIBRE"; then
	   ip link set dev eth0 name not_eth0
	   ip link set dev eth1 name eth0
	   ip link set dev not_eth0 name eth1
fi

Note: I haven't checked if it ethtool and ip do work properly if an interface is down. This is important because they should be renamed before the system brings them up (since the configuration is based on the name of the interface).

Deletions:
Thankfully, there are ways to achieve this. They can be divided in three methods:

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Oldest known version of this page was edited on 2005-03-08 21:09:10 by FreekDijkstra []

How to reorder or rename logical interfaces names in Linux

One of the problems of Linux is that the order of the network interfaces is unpredictable. Between reboots it does stay the same, but it is very well possible that after an upgrade to a new kernel or the addition or replacement of a network card (NIC) that the other of all network interface changes. For example, what used to be eth0 now becomes eth1 or eth2 or visa versa.

Obviously there is some logic to which network interface gets which name, but Linux documentation states that this may change and no user or program should ever assume anything about this. Obviously, this is annoying, in particular if your management interface is at eth1 at one node in a cluster and at eth2 in another node of the same cluster (which we have experienced). I personally like to have my (primary) mangement interface always to be at eth0.

Thankfully, there are ways to achieve this. They can be divided in three methods:

Note: Linux kernels up to 2.4 did only probe for the first Ethernet card, ignoring other NICs. We assume you use a 2.6 or higher kernel or already fixed this, for example by specifying ether=0,0,eth1 as kernel parameter∞.

Based on the physical location in the computer

Warning: This only works if the driver is built into the kernel, not as a loadable module.

Note: It is relatively hard to get this to work, and we encountered problems with it. |the other methods are recommended.

It is possible to name the network interfaces based on the interrupt (IRQ) and memory address. This should work if you have network cards in PCI busses, and it involves appending the proper parameters to the "ether=" or "netdev=" kernel parameters.

First of all, you can detect the PCI slot of the devices using This is reported to fail sometimes for certain cards. Now, write down the IRQ and IO (memory) address of each network card, and use this information to specify the interface name in your LILO or GRUB configuration file.

For LILO, you need to add an add line to the appropriate boot configuration. For example:

Under grub, it can just be listed as parameter. e.g.:

More Information

http://www.tldp.org/HOWTO/Ethernet-HOWTO-8.html∞
http://www.tldp.org/HOWTO/BootPrompt-HOWTO-11.html∞

Based on the driver

Warning: This only works if the driver is not built into the kernel, but is available as a loadable module.

First of all, determine which driver is used by each network card. Thankfully Linux does have a system to load the appropriate driver automatically, based on the PCI ID∞ of the network card. Unfortunately, there is no single command to simply get the driver (and other information like the link speed) based on just the interface name in Linux. Your best bet is to look for kernel messages:

This should give you a good estimate of the driver name. You can further verify if the name you have in mind indeed does exist and is loaded:


Note:
lsmod gave:

However, the 0 indicates that these drivers are not controlling any device! That is strange, since modprobe -r tg3 and modprobe -r e1000 do disable the network cards. Apparently, this is a flaw in lsmod.

Note that running modprobe tg3 en then modprobe e1000 does bring them up in the correct order, with the correct interface names. This is a good check if this approach (using the driver to decide the interface name) can work.

Red Hat

In Red Hat, if the driver is called "tg3" (the Tigon driver), you simply specify the network name by adding this enty in /etc/modules.conf:

Debian

On a Debian system, /etc/modules.conf is generated automatically and should not be edited directly. Instead, create a file in the subdirectory /etc/modules/ (do not use /etc/modprobe.d/, that seems out-of-date). For example, create the file /etc/modutils/interfaces and add the appropriate modules. For example:

Next, update //etc/modules.conf by running:


Alternative method: I have encountered scenario's where the kernel did already load the modules for the drivers, even before /etc/modules.conf was read. The result was that in effect, the specification in /etc/modules.conf was ignored, and this method did not work. As an alternative, it is possible to also list the drivers, in the appropriate order, in /etc/modules (thus not /etc/modules.conf):

The result will be that the tg3 driver is loaded before the e1000 kernel. Since /etc/modules only exists for Debian, this trick will most likely not work for other distributions.

Based on the MAC address

Last, it is also possible to name the network interface based on the MAC address of each NIC. The advantage is that it is possible to use this method if you have two NICs which use the same driver.

As a first start, you must determine the MAC address of your interfaces. You can do this locally on a machine using
The MAC address is listed as "hwaddr" (hardware address). Alternatively, you can even determine MAC addresses remotely using ping and /sbin/arp.

There are two ways to do map the MAC address to the logical interface name. Either by using the get-mac-address.sh script, or by using the nameif program. The method bellow is know to work with Debian. Other distributions to not have the interface file , but other mechanisms for interface configuration (like /etc/sysconfig/network-scripts/ files for Red Hat). So, it may not be trivial to apply this to other distributions. However, if you succeed, we very much welcome feedback!

Using the get-mac-address.sh script

The first solution is to use the get-mac-address.sh script to do mapping by MAC address. On Debian, this script is distributed as part of the ifupdown package∞ (in /usr/share/doc/ifupdown/examples/get-mac-address.sh). With this script copied to some sane place (e.g. /usr/local/bin), you can then setup /etc/network/interfaces in this manner:



Source: https://www.gelato.unsw.edu.au/archives/gelato-technical/2004-February/000334.html∞

The disadvantage of this method is that does define a mapping, rather then changing the actual logical interface name.

Using the nameif program

Alternative to the get-mac-address.sh script, you can also use the slightly more convienant nameif program, which is distributed as part of the net-tools package∞ on Debian.

The advantage of nameif is that you can specify the interface names in the /etc/mactab file:


It is not possible to rename an interface to a name of an existing interface. So you can't rename eth1 to eth0 as long as eth0 still exists. It is possible to still swap the names eth0 and eth1 by using a temporary name (e.g. first rename eth1 to ethfoo, then eth0 to eth1 and finally ethfoo to eth0). It should be noted however, that this may lead to problems if you add another network cards or upgrade your kernel, and the interface names just before you call nameif are not as expected. Therefor, it is recommended to use other names like "ethmgmnt", "ethwired", "ethwireless" and "eth10ge", as shown in the example above.

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