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Using ifupdown2 on Ubuntu

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Sean Cavanaugh
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Cumulus Networks developed ifupdown2 to improve network configuration for standard Debian and Ubuntu instances, and has been the standard interface configuration tool for Cumulus Linux since version 2.1. This article describes how to install ifupdown2 on Ubuntu hosts.

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Verify Ubuntu Version

Before you start the install, verify the version of Ubuntu installed on the instance:

[email protected]:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.3 LTS"

Follow the appropriate instructions below for your installed version of Ubuntu.

Installing ifupdown2 on an Ubuntu Host

Ubuntu 16.04 Xenial

ifupdown2 is included in the default package list for Ubuntu 16.04. The package is available here: ifupdown2.

  1. Open /etc/apt/sources.list in an editor.

  2. Ensure the following line is uncommented, and save the file:

    deb http://us.archive.ubuntu.com/ubuntu/ xenial universe

  3. Update the Ubuntu instance:

    [email protected]:~$ sudo apt-get update

  4. Install the ifupdown2 package:

    [email protected]:~$ sudo apt-get install ifupdown2

  5. Make sure the following configuration is present in the systemd file:

    [Unit]
Description=ifupdown2 init script

[Service]
Type=oneshot
ExecStart=/sbin/ifup -a
ExecStop=/sbin/ifdown -a
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

 

Ubuntu 14.04 Trusty

ifupdown2 is not included in the default package list for Ubuntu 14.04. However, as it is included in Ubuntu 16.04, this restriction can be worked around.

Note: An ansible playbook is available to automate these tasks.

  1. Enter the root account. All of the remaining commands in these instructions assume use of the root account.

  2. Add the Ubuntu Xenial sources to your Ubuntu Trusty installation:

    [email protected]# echo "deb http://us.archive.ubuntu.com/ubuntu/ xenial universe" > /etc/apt/sources.list.d/xenial.list

  3. Update the Ubuntu package cache. You may see warnings in the output, which you can ignore:

    [email protected]# apt-get update
    <snip>
    Ign http://us.archive.ubuntu.com trusty/multiverse Translation-en_US
    Ign http://us.archive.ubuntu.com trusty/restricted Translation-en_US
    Ign http://us.archive.ubuntu.com trusty/universe Translation-en_US
    Reading package lists... Done 
    W: Unknown Multi-Arch type 'no' for package 'libkf5akonadisearch-bin'
    W: Ignoring Provides line with DepCompareOp for package php-psr-http-message-implementation
    W: Ignoring Provides line with DepCompareOp for package php-psr-log-implementation
    W: Ignoring Provides line with DepCompareOp for package php-math-biginteger
    W: Unknown Multi-Arch type 'no' for package 'libkf5akonadisearch-bin'
    W: You may want to run apt-get update to correct these problems

  4. Important: After the initial configuration, the repositories have equal preference for installing packages, resulting in the newest (Xenial) packages being installed. As the goal of this article is to install ifupdown2 only, this step ensures that Trusty packages will be installed first.

    Before continuing, you must either raise the priority for the Trusty repository  or lower the priority of the Xenial repository. The example steps below show how to lower the priority of the Xenial repository, ensuring the Trusty packages will be installed first, and Xenial packages will only be installed if no Trusty package exists:

    1. Create a file called /etc/apt/preferences.d/xenial and add the following text to the file, then save the file:

      Explanation: give xenial a low priority number
Package: *
Pin: release a=xenial
Pin-Priority: 100
      Alternatively run this command to perform the same task: 
      [email protected]# echo -e "Explanation: give xenial a low priority number\nPackage: *\nPin: release a=xenial\nPin-Priority: 100\n" > /etc/apt/preferences.d/xenial

    2. Verify that Xenial packages won't override all other packages. The example below uses the Ansible package for verification, as different versions are available on Trusty (Ansible 1.5.4), and Xenial (Ansible 1.9.4):

      [email protected]# apt-cache policy ansible
ansible:
  Installed: (none)
  Candidate: 1.5.4+dfsg-1
  Version table:
     1.9.4-1 0
        100 http://us.archive.ubuntu.com/ubuntu/ xenial/universe amd64 Packages
     1.7.2+dfsg-1~ubuntu14.04.1 0
        100 http://us.archive.ubuntu.com/ubuntu/ trusty-backports/universe amd64 Packages
     1.5.4+dfsg-1 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages

      The Candidate above is listed as 1.5.4, and the Xenial priority has been lowered from 500 to 100, which means that Xenial packages will not override Trusty repository packages.

  5. Install the ifupdown2 package dependencies:

    [email protected]# apt-get install python-ipaddr python-argcomplete python-gvgen python-mako

  6. Place a hold on the ifupdown package:

    [email protected]# echo ifupdown hold | dpkg --set-selections

  7. Download the ifupdown2 package:

    [email protected]# apt-get download ifupdown2
  8. Manually install the ifupdown2 package:
    [email protected]# dpkg --force-conflicts --force-depends --force-overwrite -i ./ifupdown2*.deb
    Selecting previously unselected package ifupdown2.
    dpkg: considering removing ifupdown in favour of ifupdown2 ...
    dpkg: warning: ignoring dependency problem with removal of ifupdown:
     upstart depends on ifupdown (>= 0.6.10ubuntu5)
     ifupdown is to be removed.

    Package ifupdown is on hold, not touching it. Use --force-hold to override.
    dpkg: regarding .../ifupdown2_1.0~git20151029-1_all.deb containing ifupdown2:
     ifupdown2 conflicts with ifupdown
     ifupdown (version 0.7.47.2ubuntu4.1) is present and installed.

    dpkg: warning: ignoring conflict, may proceed anyway!
    (Reading database ... 197912 files and directories currently installed.)
    Preparing to unpack .../ifupdown2_1.0~git20151029-1_all.deb ...
    Unpacking ifupdown2 (1.0~git20151029-1) ...
    Replacing files in old package ifupdown (0.7.47.2ubuntu4.1) ...
    dpkg: ifupdown2: dependency problems, but configuring anyway as you requested:
     ifupdown2 depends on init-system-helpers (>= 1.18~); however:
     Version of init-system-helpers on system is 1.14.

    Setting up ifupdown2 (1.0~git20151029-1) ...
    Installing new version of config file /etc/init.d/networking ...
    update-rc.d: warning: default start runlevel arguments (2 3 4 5) do not match networking Default-Start values (S)
    Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
    Processing triggers for ureadahead (0.100.0-16) ...
    ureadahead will be reprofiled on next reboot

  9. Examine the "Depends" and "Conflicts" lines from the installed ifupdown2 package.

    [email protected]# grep -A 34 "Package: ifupdown2" /var/lib/dpkg/status
    Package: ifupdown2
    Status: install ok installed
    Priority: optional
    Section: admin
    Installed-Size: 595
    Maintainer: Ubuntu Developers <[email protected]>
    Architecture: all
    Version: 1.0~git20151029-1
    Replaces: ifupdown
    Provides: ifupdown
    Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.18~), python-argcomplete, python-ipaddr
    Suggests: python-gvgen, python-mako
    Conflicts: ifupdown
    Conffiles:
     /etc/default/networking/networking.default 76a6935f125a8db5cbcddee1d422fc81
     /etc/init.d/networking 703fab9e50c7c539efc6e1ce6b9c7633
     /etc/network/ifupdown2/addons.conf c39be66aa58f59b4343c9dc6541043fe
     /etc/network/ifupdown2/ifupdown2.conf 85fd2d75c77c6b68438a16888ae08510
    Description: Network Interface Management tool similar to ifupdown
     ifupdown2 is ifupdown re-written in Python. It replaces ifupdown and provides
     the same user interface as ifupdown for network interface configuration.
     Like ifupdown, ifupdown2 is a high level tool to configure (or, respectively
     deconfigure) network interfaces based on interface definitions in
     /etc/network/interfaces. It is capable of detecting network interface
     dependencies and comes with several new features which are available as
     new command options to ifup/ifdown/ifquery commands. It also comes with a new
     command ifreload to reload interface configuration with minimum
     disruption. Most commands are also capable of input and output in JSON format.
     It is backward compatible with ifupdown /etc/network/interfaces format and
     supports newer simplified format. It also supports interface templates with
     python-mako for large scale interface deployments. See
     /usr/share/doc/ifupdown2/README.rst for details about ifupdown2. Examples
     are available under /usr/share/doc/ifupdown2/examples.
    Original-Maintainer: Roopa Prabhu <[email protected]>
    Homepage: https://github.com/CumulusNetworks/ifupdown2

  10. Optional: At this point you need to amend the package manager's understanding of the dependencies and conflicts for the ifupdown2 package. This requires two very precise edits to the /var/lib/dpkg/status file. To ensure that those edits produce the desired changes, first confirm that that the two find-and-replaces that you will perform in Step 11 will each only have one instance to replace.

    [email protected]# grep -c "Conflicts: ifupdown" /var/lib/dpkg/status
    1
    [email protected]# grep -c "Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.18~), python-argcomplete, python-ipaddr" /var/lib/dpkg/status
    1

  11. Update the package manager with new dependency and conflict information for the ifupdown2 package by using the sed command to find and replace the two lines (shown in red during Step 9):

    [email protected]# sed -i "s/Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.18~), python-argcomplete, python-ipaddr/Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.14~), python-argcomplete, python-ipaddr/g" /var/lib/dpkg/status
    [email protected]# sed -i "/Conflicts: ifupdown/d" /var/lib/dpkg/status

  12. Confirm the edits to the file were made successfully. Note that the minimum required init-system-helpers version has changed from 1.18 to 1.14 and the "Conflicts" line is gone entirely when compared to Step 9:

    [email protected]# grep -A 34 "Package: ifupdown2" /var/lib/dpkg/status
    Package: ifupdown2
    Status: install ok installed
    Priority: optional
    Section: admin
    Installed-Size: 595
    Maintainer: Ubuntu Developers <[email protected]>
    Architecture: all
    Version: 1.0~git20151029-1
    Replaces: ifupdown
    Provides: ifupdown
    Depends: python:any (>= 2.7.5-5~), init-system-helpers (>= 1.14~), python-argcomplete, python-ipaddr
    Suggests: python-gvgen, python-mako
    Conffiles:
     /etc/default/networking/networking.default 76a6935f125a8db5cbcddee1d422fc81
     /etc/init.d/networking 703fab9e50c7c539efc6e1ce6b9c7633
     /etc/network/ifupdown2/addons.conf c39be66aa58f59b4343c9dc6541043fe
     /etc/network/ifupdown2/ifupdown2.conf 85fd2d75c77c6b68438a16888ae08510
    Description: Network Interface Management tool similar to ifupdown
     ifupdown2 is ifupdown re-written in Python. It replaces ifupdown and provides
     the same user interface as ifupdown for network interface configuration.
     Like ifupdown, ifupdown2 is a high level tool to configure (or, respectively
     deconfigure) network interfaces based on interface definitions in
     /etc/network/interfaces. It is capable of detecting network interface
     dependencies and comes with several new features which are available as
     new command options to ifup/ifdown/ifquery commands. It also comes with a new
     command ifreload to reload interface configuration with minimum
     disruption. Most commands are also capable of input and output in JSON format.
     It is backward compatible with ifupdown /etc/network/interfaces format and
     supports newer simplified format. It also supports interface templates with
     python-mako for large scale interface deployments. See
     /usr/share/doc/ifupdown2/README.rst for details about ifupdown2. Examples
     are available under /usr/share/doc/ifupdown2/examples.
    Original-Maintainer: Roopa Prabhu <[email protected]>
    Homepage: https://github.com/CumulusNetworks/ifupdown2

  13. Disable the Xenial package repository until you need it again:

    [email protected]# sed -i "s/deb/#deb/g" /etc/apt/sources.list.d/xenial.list

  14. Update the Ubuntu package cache again to remove the Xenial sources from the package cache.

    [email protected]# apt-get update

Verifying ifupdown2

Once ifupdown2 is installed, ifupdown2-specific commands can be used to test and verify:

[email protected]:~$ sudo ifquery -ra
auto lo
iface lo inet loopback
	mtu 65536

auto eth0
iface eth0
	address 10.50.10.160/24
	link-speed 1000
	link-duplex full
	link-autoneg on

Installing Other Tools

In addition, you can install other tools so the host more closely resembles Cumulus Linux:

  • Install netshow to retrieve a lot of information about your network configuration. It's very easy with the Python package manager PIP:
    [email protected]:~$ sudo apt-get install python-pip
[email protected]:~$ sudo pip install netshow-linux-lib

  • Install the brctl and bridge commands to get information and configure your bridges:

    [email protected]:~$ sudo apt-get install bridge-utils

You can now review bridges on the host in the same way as in Cumulus Linux:

[email protected]:~$ ifquery -a
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto bridge
iface bridge
	bridge-ports eth1
	bridge-stp on

Use the brctl command to look at the bridge STP state:

[email protected]:~$ brctl show
bridge name	bridge id		STP enabled	interfaces
bridge		8000.080027d73d5d	yes		eth1

Removing ifupdown2

  1. Remove the package in the normal Debian/Ubuntu manner:
    sudo apt-get remove ifupdown2
  2. On Ubuntu 14.04 only:
    sudo apt-get install ifupdown --reinstall

Further Reading

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