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Lab 11.1



I’d like to comment on some questions regarding the exercise 11.1.
Firstly, to say that, although I try, from time to time, to do the exercises with CentOS and Opensuse, I am choosing to do it with Ubuntu mainly. I do this because, supposedly for the exam we will have to choose one of them. So, if I’m not doing wrong, it’s better to be specialized on one of this Linux families than having a slight idea of all of them. The reason I choose Debian/Ubuntu family is that is what I use mainly and I have previous knowledge.
I noticed on several labs that, on some cases, Debian and Ubuntu are treated as if they worked in the same way. This could be right on some cases, perhaps it is right most of the time, but sometimes like on this exercise it’s not true.
The networking tools on Ubuntu are now (from 18.04 onward) different from Debian ones. The main configuration file it’s not /etc/network/interfaces and it has a tool called netplan instead.
The easiest and more logical way to do many of the labs on an Ubuntu machine is using this tool that is the default one on recent Ubuntu installations. If I choose to do my certifications tests with an Ubuntu machine what am I supposed to do then?
Should I use the default tools provided by the machine that are not covered on this course?
Or should I mess with the default configuration installing other software or changing the default configuration adding potential problems to the scenario that I will have to work with in the test?
The confusion I have is greater when I saw that, specifically in this exercise 11.1, the solution indicated in the lab does not work for me using /etc/networking/interfaces way of doing. What does not work is that I can’t make changes persistent across reboots. And that is the purpose of doing in that way. If I create a Vlan-trunked interface with ip command it works, but if I try to configure it on /etc/network/interfaces it doesn’t work. I test this on a Debian 10 virtual machine.
If I do it on an Ubuntu 20.04 machine using the netplan tools following for instance this instructions it works perfectly.
What am I supposed to do if I decide to pass the test with an Ubuntu machine? Do it with its default settings and tools and study them and learn how to handle them on my own? Taking risks configuring the machine for using Network Manager or networking scripts having that this could lead to have an unstable machine? Different networking tools can interfere with each others.
Also, I would like to take the opportunity to ask why it does not work for me in Debian.
What I do is the following:

  • Install vlan : apt install vlan.
  • Load module : modprobe 8021q (I try adding 8021q to /etc/modules too)
  • And my /etc/network/interface file is:
auto lo
iface lo inet loopback
allow-hotplug enp0s3
iface enp0s3 inet static
auto enp0s03.7
iface enp0s3.7 inet static
    vlan-raw-device enp0s3

It’s the same if I reboot the machine or if I use the ifup command ou if I use systemctl. It always fails. The output of systemctl status networking:

root@dserver:~# systemctl status networking
● networking.service - Raise network interfaces
   Loaded: loaded (/lib/systemd/system/networking.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Sat 2021-05-15 11:55:51 CEST; 3min 15s ago
     Docs: man:interfaces(5)
  Process: 320 ExecStart=/sbin/ifup -a --read-environment (code=exited, status=1/FAILURE)
 Main PID: 320 (code=exited, status=1/FAILURE)

Mai 15 11:55:51 dserver systemd[1]: Starting Raise network interfaces...
Mai 15 11:55:51 dserver ifup[320]: ifup: unknown interface enp0s03.7
Mai 15 11:55:51 dserver systemd[1]: networking.service: Main process exited, code=exited, status=1/FAILURE
Mai 15 11:55:51 dserver systemd[1]: networking.service: Failed with result 'exit-code'.
Mai 15 11:55:51 dserver systemd[1]: Failed to start Raise network interfaces.


  • coop
    coop Posts: 915

    I am not the SME for this course and I do not compose or review the exams. However, the question of netplan and the idiosyncratic use of netplan on Ubuntu has repeatedly come up in the forums before. Both how to configure with it, and more importantly, how to shove it out of the way have been thoroughly explained. My well-founded understanding is that the certification exam designers try to use tools that are universal whenever possible, and avoid others. So you can't avoid rpm vs dpkg, but you can avoid netplan as it is not needed for anything. No other distro,to my knowledge, has shown any interest in netplan. It is true you are likely to encounter it in the wild unfortunately, so learning it is still extra credit.

    As far as Debian goes, other than netplan you have to work to find real CLI differences. Note we don't teach "snap" either. It can also be avoided (not obliterated) with a one line command, much like netplan

  • jmarinho
    jmarinho Posts: 19

    I do not want to start any controversy about which tools should or should not be considered. What I want is to point out that I have paid a good amount of money for this course and I think that gives me the right to, at least, suggest as a student some aspects that I think would improve the training given.
    If, apparently, in the course the netplan tool is going to be ignored because it is not widely used, perhaps that should be taken into account throughout the course and indicate the steps in the course material, not in a forum thread, that must be given to configure the equipment with network manager, networking scripts or whatever. So that the exercises and, finally, the certification test can be carried out successfully.
    I have repeated the exercise on an Ubuntu 20.04 machine but this time using the method described in the exercise for a Debian / Ubuntu machine.
    The first thing to keep in mind is that in Ubuntu 20.04 you must first do some changes because if not you can’t do the exercise as is described on the solution. Here are some valid instructions for doing that (I follow all the instructions except the step involving interfaces names)
    I also have to say that on Debian, the exercise did not work because of a typo of mine in line 9 of the interfaces file in the previous post so I apologize for the error.
    In summary, I think that these aspects should be clarified a little better in the course because, although it is true that many times you learn by going around a thousand times, you also lose a lot of time and one of the reasons why I joined this bootcamp was to give me a well-prepared material on which to focus without taking too many detours.
    Thank you for the reply and I am sorry for the inconvenience caused by bringing up a topic already discussed before.


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