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Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

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  Jessie to Stretch Upgrade: Enable Predictable Network Interface Names debian-lists@patschie.de - 2017-07-27 17:30 +0200
    Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Michael Biebl <biebl@debian.org> - 2017-07-27 18:00 +0200
      Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names debian-lists@patschie.de - 2017-07-27 18:10 +0200
        Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Greg Wooledge <wooledg@eeg.ccf.org> - 2017-07-27 18:20 +0200
          Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Patrick Flaig <patrick@patschie.de> - 2017-07-27 18:50 +0200
        Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Michael Biebl <biebl@debian.org> - 2017-07-27 18:30 +0200
          Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Patrick Flaig <patrick@patschie.de> - 2017-07-27 18:50 +0200
          Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names debian-lists@patschie.de - 2017-07-27 19:00 +0200
            Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Michael Biebl <biebl@debian.org> - 2017-07-27 19:30 +0200
              Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Michael Biebl <biebl@debian.org> - 2017-07-27 20:00 +0200
                Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Patrick Flaig <debian-lists@patschie.de> - 2017-07-27 20:30 +0200
                  Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Michael Biebl <biebl@debian.org> - 2017-07-27 21:30 +0200
                    Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Patrick Flaig <debian-lists@patschie.de> - 2017-07-27 22:20 +0200
              Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface  Names Patrick Flaig <debian-lists@patschie.de> - 2017-07-27 20:00 +0200

#184310 — Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

Hi,

I’m running into some troubles to enable the predictable network interface names for a system upgraded from Jessie.

What I figured out so far:
Setting net.ifnames=1 on the kernel command line doesn’t help and seems no longer to be supported parameter (at least "sysctl - a" doesn’t show it).
Removing any /etc/udev/rules.d/ file handling the network interface doesn’t bring the desired effect of having predictable network interface names.

I started now to compare /lib/udev/rules.d from a clean stretch installation with the files on a upgraded system, the clean installation has much more files.
So next try reinstalling udev to get all missing/new rule files from stretch, but that didn’t work either.

Any ideas what I could try next or missed to check?

Thanks a lot.

Patrick

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#184313 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

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Hi Patrick

Am 27.07.2017 um 17:15 schrieb debian-lists@patschie.de:
> Hi,
> 
> I’m running into some troubles to enable the predictable network interface names for a system upgraded from Jessie.
> 
> What I figured out so far:
> Setting net.ifnames=1 on the kernel command line doesn’t help and seems no longer to be supported parameter (at least "sysctl - a" doesn’t show it).

Setting that parameter should work, but it doesn't take precedence over
an existing /etc/udev/rules.d/70-persistent-net.rules

Since net.ifnames=1 is the default since stretch, you don't need to set
it explicitly though.

> Removing any /etc/udev/rules.d/ file handling the network interface doesn’t bring the desired effect of having predictable network interface names.
> 
> I started now to compare /lib/udev/rules.d from a clean stretch installation with the files on a upgraded system, the clean installation has much more files.
> So next try reinstalling udev to get all missing/new rule files from stretch, but that didn’t work either.
> 
> Any ideas what I could try next or missed to check?
> 

Most likely the file /etc/udev/rules.d/70-persistent-net.rules got
embedded in the initramfs. So once you removed that file, you also need
to rebuild the initramfs via update-initramfs -u

Michael

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#184314 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

Hi Michael,

I forgot to mention that I also recreated the initramfs: 
after several tries just to update it, I deleted the initramfs and recreated it completely.
But still the same effect.

Is there a way to manually check the contents of the initramfs, just to make sure that the 70-persistent-net.rules isn’t there?

Patrick

> Am 27.07.2017 um 17:57 schrieb Michael Biebl <biebl@debian.org>:
> 
> Hi Patrick
> 
> Am 27.07.2017 um 17:15 schrieb debian-lists@patschie.de:
>> Hi,
>> 
>> I’m running into some troubles to enable the predictable network interface names for a system upgraded from Jessie.
>> 
>> What I figured out so far:
>> Setting net.ifnames=1 on the kernel command line doesn’t help and seems no longer to be supported parameter (at least "sysctl - a" doesn’t show it).
> 
> Setting that parameter should work, but it doesn't take precedence over
> an existing /etc/udev/rules.d/70-persistent-net.rules
> 
> Since net.ifnames=1 is the default since stretch, you don't need to set
> it explicitly though.
> 
>> Removing any /etc/udev/rules.d/ file handling the network interface doesn’t bring the desired effect of having predictable network interface names.
>> 
>> I started now to compare /lib/udev/rules.d from a clean stretch installation with the files on a upgraded system, the clean installation has much more files.
>> So next try reinstalling udev to get all missing/new rule files from stretch, but that didn’t work either.
>> 
>> Any ideas what I could try next or missed to check?
>> 
> 
> Most likely the file /etc/udev/rules.d/70-persistent-net.rules got
> embedded in the initramfs. So once you removed that file, you also need
> to rebuild the initramfs via update-initramfs -u
> 
> Michael
> 

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#184315 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

On Thu, Jul 27, 2017 at 06:04:49PM +0200, debian-lists@patschie.de wrote:
> Is there a way to manually check the contents of the initramfs, just to make sure that the 70-persistent-net.rules isn’t there?

mkdir /tmp/foo &&
cd /tmp/foo &&
unmkinitramfs /boot/initrd.whatever

(The old way of just running cpio won't work any more, because the new
initrd.img files are a concatenation of multiple cpio archives.)

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#184319 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

Thanks,

confirmed, the initrd doesn’t contain any udev rule files in /etc/udev/rules.d
 
> Am 27.07.2017 um 18:11 schrieb Greg Wooledge <wooledg@eeg.ccf.org>:
> 
> On Thu, Jul 27, 2017 at 06:04:49PM +0200, debian-lists@patschie.de wrote:
>> Is there a way to manually check the contents of the initramfs, just to make sure that the 70-persistent-net.rules isn’t there?
> 
> mkdir /tmp/foo &&
> cd /tmp/foo &&
> unmkinitramfs /boot/initrd.whatever
> 
> (The old way of just running cpio won't work any more, because the new
> initrd.img files are a concatenation of multiple cpio archives.)
> 

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#184316 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

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Am 27.07.2017 um 18:04 schrieb debian-lists@patschie.de:
> Hi Michael,
> 
> I forgot to mention that I also recreated the initramfs: 
> after several tries just to update it, I deleted the initramfs and recreated it completely.
> But still the same effect.
> 
> Is there a way to manually check the contents of the initramfs, just to make sure that the 70-persistent-net.rules isn’t there?


lsinitramfs /boot/initrd.img-$(uname -r) | grep  70-persistent-net.rules

This should come up empty.

The new naming is setup via /lib/udev/rules.d/80-net-setup-link.rules
and a link file called  99-default.link

lsinitramfs /boot/initrd.img-$(uname -r) | grep  80-net-setup-link.rules
lib/udev/rules.d/80-net-setup-link.rules
lsinitramfs /boot/initrd.img-$(uname -r) | grep 99-default.link
lib/systemd/network/99-default.link

Is this a bare metal or a VM?
-- 
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?

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#184318 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

> Am 27.07.2017 um 18:25 schrieb Michael Biebl <biebl@debian.org>:
> 
> Am 27.07.2017 um 18:04 schrieb debian-lists@patschie.de:
>> Hi Michael,
>> 
>> I forgot to mention that I also recreated the initramfs: 
>> after several tries just to update it, I deleted the initramfs and recreated it completely.
>> But still the same effect.
>> 
>> Is there a way to manually check the contents of the initramfs, just to make sure that the 70-persistent-net.rules isn’t there?
> 
> 
> lsinitramfs /boot/initrd.img-$(uname -r) | grep  70-persistent-net.rules
> 
> This should come up empty.
Confirmed
> 
> The new naming is setup via /lib/udev/rules.d/80-net-setup-link.rules
> and a link file called  99-default.link
99-default.link is missing
> 
> lsinitramfs /boot/initrd.img-$(uname -r) | grep  80-net-setup-link.rules
> lib/udev/rules.d/80-net-setup-link.rules
Available
> lsinitramfs /boot/initrd.img-$(uname -r) | grep 99-default.link
> lib/systemd/network/99-default.link
Missing
> 
> Is this a bare metal or a VM?
VirtualBox VM, as well as the Stretch clean install system, where the predictable names are working fine. 
> -- 
> Why is it that all of the instruments seeking intelligent life in the
> universe are pointed away from Earth?
> 

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#184320 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

> Am 27.07.2017 um 18:25 schrieb Michael Biebl <biebl@debian.org>:
> 
> Am 27.07.2017 um 18:04 schrieb debian-lists@patschie.de:
>> Hi Michael,
>> 
>> I forgot to mention that I also recreated the initramfs: 
>> after several tries just to update it, I deleted the initramfs and recreated it completely.
>> But still the same effect.
>> 
>> Is there a way to manually check the contents of the initramfs, just to make sure that the 70-persistent-net.rules isn’t there?
> 
> 
> lsinitramfs /boot/initrd.img-$(uname -r) | grep  70-persistent-net.rules
> 
> This should come up empty.
Confirmed
> 
> The new naming is setup via /lib/udev/rules.d/80-net-setup-link.rules
> and a link file called  99-default.link
99-default.link is missing
> 
> lsinitramfs /boot/initrd.img-$(uname -r) | grep  80-net-setup-link.rules
> lib/udev/rules.d/80-net-setup-link.rules
Available
> lsinitramfs /boot/initrd.img-$(uname -r) | grep 99-default.link
> lib/systemd/network/99-default.link
Missing
> 
> Is this a bare metal or a VM?
VirtualBox VM, as well as the Stretch clean install system, where the predictable names are working fine. 
> -- 
> Why is it that all of the instruments seeking intelligent life in the
> universe are pointed away from Earth?
> 

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#184321 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

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Am 27.07.2017 um 18:55 schrieb debian-lists@patschie.de:

>> Am 27.07.2017 um 18:25 schrieb Michael Biebl <biebl@debian.org>:
>> lsinitramfs /boot/initrd.img-$(uname -r) | grep 99-default.link
>> lib/systemd/network/99-default.link
> Missing

Odd. Do you have that file on the host system?
Can you check with debsums -as udev systemd.

/usr/share/initramfs-tools/hooks/udev should copy that link file into
the initramfs.

Do you by chance have any custom initramfs hooks in
/etc/initramfs-tools/hooks which override the udev hook?

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#184324 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

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Am 27.07.2017 um 19:50 schrieb Patrick Flaig:
> Oh my fault, 99-default.link is available, I checked the wrong folder.
> The file is containing some text, saying that the machine is most likely a virtualized guest.

Can you paste the contents verbatim.


-- 
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?

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#184326 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

Sure, this is the content:

cat /tmp/foo/lib/systemd/network/99-default.link 
# This machine is most likely a virtualized guest, where the old persistent
# network interface mechanism (75-persistent-net-generator.rules) did not work.
# This file disables /lib/systemd/network/99-default.link to avoid
# changing network interface names on upgrade. Please read
# /usr/share/doc/udev/README.Debian.gz about how to migrate to the currently
# supported mechanism.

The content of the README, doesn’t help that much as 99-default.link doesn’t seem to be a symlink.

cat /usr/share/doc/udev/README.Debian 
This documents udev integration Debian specifics. Please see man udev(7) and
its referenced manpages for general documentation.

Network interface naming
~~~~~~~~~~~~~~~~~~~~~~~~
Since version 197 udev has a builtin persistent name generator which checks
firmware/BIOS provided index numbers or slot names (similar to biosdevname),
falls back to slot names (PCI numbers, etc., in the spirit of
/dev/disks/by-path/), and then optionally falls back to MAC address, and
generates names based on these properties. This provides "location oriented"
names for PCI cards such as "enp0s1" for ethernet, or wlp1s0" for a WIFI card
so that replacing a broken network card does not change the name. As location
based naming does not work well for USB devices, these use a MAC based naming
schema (see /lib/udev/rules.d/73-usb-net-by-mac.rules).

This has been enabled by default since udev 220-7, which affects new
installations/hardware. Existing installations/hardware which already got
covered by the old 75-persistent-net-generator.rules will keep their interface
names, see below.

You can disable these stable names and go back to the kernel-provided ones
(which don't have a stable order) in one of two ways:

  - Put "net.ifnames=0" into the kernel command line (e. g. in
    /etc/default/grub's GRUB_CMDLINE_LINUX_DEFAULT, then run "update-grub").

  - Disable the default *.link rules with
    "ln -s /dev/null /etc/systemd/network/99-default.link"
    and rebuild the initrd with "update-initramfs -u".

See this page for more information:
http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/

Legacy persistent network interface naming
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Debian releases up to 8 ("Jessie") and Ubuntu up to 15.04 had an udev rule
/lib/udev/rules.d/75-persistent-net-generator.rules which fixed the name of a
network interface that it got when its MAC address first appeared in a
dynamically created /etc/udev/rules.d/70-persistent-net.rules file.

This had inherent race conditions (which sometimes caused collisions and
interface names like "rename1"), required having to write state into /etc
(which isn't possible for read-only root), and did not work in virtualized
environments.

This old schema is deprecated in Debian 9 ("Stretch"), and will not
be supported any more in Debian 10.

Migration to the current network interface naming
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
On package upgrade systems will keep their current names, but they will need to
be manually migrated by Debian 10 / Ubuntu 18.04 LTS.  If you rely on the old
names in custom ifupdown stanzas, firewall scripts or other networking
configuration, these need to be updated to the new names.

First, determine all relevant network interface names: those in
/etc/udev/rules.d/70-persistent-net.rules, or if that does not exist (in
virtual machines), in "ip link" or /sys/class/net/.

Then for every interface name use a command like

  grep -r eth0 /etc

to find out where it is being used.

Then on "real hardware" machines, rename the file to
70-persistent-net.rules.old; on VMs remove the file
/etc/udev/rules.d/80-net-setup-link.rules instead.

Reboot, adjust configuration files, and test your system.

Custom net interface naming
~~~~~~~~~~~~~~~~~~~~~~~~~~~
In some cases it is convenient to define your own specific names for network
interfaces. These can be customized in two different ways:

 * You can create your own names via udev rules, based on arbitrary attribute
   and property matches. See man udev(7) for documentation how to write udev
   rules. For example, you can create /etc/udev/rules.d/76-netnames.rules with

   ------------ snip ----------
   # identify device by MAC address
   SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="11:22:aa:bb:cc:33", NAME="eth-dmz"

   # identify by vendor/model ID
   SUBSYSTEM=="net", ACTION=="add", ENV{ID_VENDOR_ID}=="0x8086", \
       ENV{ID_MODEL_ID}=="0x1502", NAME="eth-intel-gb"

   # USB device by path
   # get ID_PATH if not present yet
   ENV{ID_PATH}=="", IMPORT{builtin}="path_id"
   SUBSYSTEM=="net", ACTION=="add", ENV{ID_PATH}=="*-usb-0:3:1*", NAME="eth-blue-hub"
   ------------ snip ----------

   The name of the rules file needs to have a prefix smaller than "80" so that
   it runs before /lib/udev/rules.d/80-net-setup-link.rules, and should have a
   prefix bigger than "75" so that it runs after 75-net-description.rules and
   thus you can use matches on ID_VENDOR and similar properties.

 * Unless you disabled net.ifnames, you can change the policy
   (kernel/bios/path/MAC based naming) in an /etc/systemd/network/*.link file,
   for individual devices or entire device classes. See man systemd.link(5) for
   details about this. /lib/systemd/network/99-default.link is the default
   policy, and /lib/systemd/network/01-mac-for-usb.link makes it use MAC based
   names for USB devices.

Any of the above changes require an initrd update with "update-initramfs -u" to
get effective.

Using udev with LDAP or NIS
~~~~~~~~~~~~~~~~~~~~~~~~~~~
If the rules files reference usernames or groups not present in the
/etc/{passwd,group} files and the system is configured to use a
network-based database like LDAP or NIS then udev may fail at boot time
because users and groups are looked up well before the network has been
initialized.
A possible solution is to configure /etc/nsswitch.conf like this:

  passwd:         files ldap [UNAVAIL=return]
  group:          files ldap [UNAVAIL=return]

The nsswitch.conf syntax is documented in the glibc manual.

> Am 27.07.2017 um 19:56 schrieb Michael Biebl <biebl@debian.org>:
> 
> Am 27.07.2017 um 19:50 schrieb Patrick Flaig:
>> Oh my fault, 99-default.link is available, I checked the wrong folder.
>> The file is containing some text, saying that the machine is most likely a virtualized guest.
> 
> Can you paste the contents verbatim.
> 
> 
> -- 
> Why is it that all of the instruments seeking intelligent life in the
> universe are pointed away from Earth?
> 

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#184328 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

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Am 27.07.2017 um 20:21 schrieb Patrick Flaig:
> Sure, this is the content:
> 
> cat /tmp/foo/lib/systemd/network/99-default.link 

Thanks Patrick.
So, it seems the udev maintainer scripts detected at virtualized
environment which causes the following code to be triggered:

https://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/udev.postinst#n49

The /etc/systemd/network/99-default.link file overrides the the package
provided one from /lib/systemd/network/99-default.link

So, in order to enable the new naming scheme, remove
/etc/systemd/network/99-default.link then rebuild the initramfs.

On the next boot you should have the new network interface names.

Regards,
Michael


-- 
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?

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#184330 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

Hi Michael,

great, that was the problem, removed the file, recreated the initramfs, now it works like a charm.
Thanks a lot for the help.

Patrick

> Am 27.07.2017 um 21:29 schrieb Michael Biebl <biebl@debian.org>:
> 
> Am 27.07.2017 um 20:21 schrieb Patrick Flaig:
>> Sure, this is the content:
>> 
>> cat /tmp/foo/lib/systemd/network/99-default.link 
> 
> Thanks Patrick.
> So, it seems the udev maintainer scripts detected at virtualized
> environment which causes the following code to be triggered:
> 
> https://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/udev.postinst#n49
> 
> The /etc/systemd/network/99-default.link file overrides the the package
> provided one from /lib/systemd/network/99-default.link
> 
> So, in order to enable the new naming scheme, remove
> /etc/systemd/network/99-default.link then rebuild the initramfs.
> 
> On the next boot you should have the new network interface names.
> 
> Regards,
> Michael
> 
> 
> -- 
> Why is it that all of the instruments seeking intelligent life in the
> universe are pointed away from Earth?
> 

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#184325 — Re: Jessie to Stretch Upgrade: Enable Predictable Network Interface Names

Oh my fault, 99-default.link is available, I checked the wrong folder.
The file is containing some text, saying that the machine is most likely a virtualized guest.

> Am 27.07.2017 um 19:28 schrieb Michael Biebl <biebl@debian.org>:
> 
> Am 27.07.2017 um 18:55 schrieb debian-lists@patschie.de:
> 
>>> Am 27.07.2017 um 18:25 schrieb Michael Biebl <biebl@debian.org>:
>>> lsinitramfs /boot/initrd.img-$(uname -r) | grep 99-default.link
>>> lib/systemd/network/99-default.link
>> Missing
> 
> Odd. Do you have that file on the host system?
> Can you check with debsums -as udev systemd.
> 
> /usr/share/initramfs-tools/hooks/udev should copy that link file into
> the initramfs.
> 
> Do you by chance have any custom initramfs hooks in
> /etc/initramfs-tools/hooks which override the udev hook?
> 
> 

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