ifdown does not recognize interface

Question

I am trying to use ifdown command on my network interface (enp0s3), but it claims, that this interface is not known. When I try the same command with my loopback lo it works fine. What could be the problem ? My network-manager is sure off, only networking daemon is running.

lsb_release -d

Ubuntu 18.04.1 LTS

cat /etc/netplan/50-cloud.init.yami

You should probably know, it is on VM.

ifup and ifdown generally only affect interfaces that are declared in /etc/network/interfaces. I suspect yours is not. Did you try: sudo ifconfig enp0s3 down? — chili555, Feb 14 '19 at 15:30
ifconfig works fine thanks. Even thought I added my interface into /etc/network/interfaces in this form : auto enp0s3 it still does not work, and claim unrecognized interface. — John Ronald, Feb 14 '19 at 15:33
Please add output of nmcli general status to your question. — Pilot6, Feb 14 '19 at 15:39
Please edit your question to show the result of: lsb_release -d and also: cat /etc/network/interfaces — chili555, Feb 14 '19 at 15:49
What version Ubuntu? Edit your question with the output of cat /etc/netplan/*.yaml. Report back to @heynnema — heynnema, Feb 14 '19 at 15:49

heynnema · Answer 1 · 2022-11-08T14:00:51.737

You're currently set to use networkd, not NetworkManager.

ifup and ifdown and nmcli are NetworkManager commands.

Remove all modifications to /etc/network/interfaces.

You should work with the ip command. Type man ip for more info.

Here are some example ip commands that should work for you...

   ip addr
       Shows addresses assigned to all network interfaces.
ip neigh
       Shows the current neighbor table in kernel.
ip link set enp0s3 up
       Bring up interface enp0s3.
ip link set enp0s3 down
       Bring down interface enp0s3.
ip route
       Show table routes.

Minor twit... your /etc/netplan/*.yaml file should look like this... spacing and indentation are very important...

network:
  version: 2
  renderer: networkd
  ethernets:
    enp0s3:
      addresses: [192.168.0.110/24]
      gateway4: 192.168.0.1
      nameservers:
        addresses: [8.8.8.8, 8.8.4.4]

Or, if you wish to use NetworkManager...

network:
  version: 2
  renderer: NetworkManager

Followed by:

sudo netplan generate

sudo netplan apply

score 0 · Answer 2 · edited Feb 14 '19 at 16:32

0

Make sure, that you define the interface enp0s3 here: /etc/network/interfaces.

edited Feb 14 '19 at 16:32

Kristopher Ives

5,509

answered Feb 14 '19 at 15:32

Dominik K

306

This is not a good idea. – Pilot6 Feb 14 '19 at 15:32
If this interface is not defined in the stated file, the command ifdown won't find it. – Dominik K Feb 14 '19 at 15:36
Do you know the syntax of this definition of interface ? – John Ronald Feb 14 '19 at 15:42
Depends on your network configuration, but take a look here: https://wiki.debian.org/NetworkConfiguration (Configuring the interface manually) – Dominik K Feb 14 '19 at 15:45
Yeah, I tried something like this. But after restarting networking service, it show error. "Unknown interface enp0s3". – John Ronald Feb 14 '19 at 15:47
And what exaclty did you put in it?
Something like iface enp0s3 inet dhcp should be sufficient :/ – Dominik K Feb 14 '19 at 15:53
I only put in auto enp0s3, and that was enough for that error. – John Ronald Feb 14 '19 at 16:10
The user is using netplan, not NetworkManager, so this doesn't apply. – heynnema Feb 14 '19 at 17:34

ifdown does not recognize interface

2 Answers2