Wondering how to fix SolusVM: “cannot find device eth0” error? We can help you

Often SolusVM users report to us that they get this error while using their network.

Here at Bobcares, we handle requests from our customers to fix similar errors as a part of our Server Management Services.

Today we will see how our Support Engineers fix this for our customers.

How to fix SolusVM: “cannot find device eth0” error?

Before going into the steps for fixing this error we can see what causes this error.

Following are the two main causes for this error:

1. Network speed limiting does not work
2. SolusVM Traffic Shaping limits are not working

Now we will see the steps that our Support Engineers follow to fix this error for each of the above causes.

1. Network speed limiting does not work on the SolusVM slave node

The following error can be seen while trying to apply network limit manually on the slave node:

# php /usr/local/solusvm/includes/trafficloader.php --mode=all --debug=1
...
ADDING QDISC TO eth0
Cannot find device "eth0"

Cause

The wrong Network Interface is set up for the slave node in SolusVM.

Steps to fix:

1. Firstly, we need to connect to KVM slave node via SSH

2. Then find the main interface name using the following command:

# brctl show | grep "br"| grep -v intbr| grep -v name| awk {'print $4'}

3. After that log in to the SolusVM admin panel.

4. And browse to SolusVM take Nodes and click Edit.

5. Finally we can provide the correct Network Interface and click Update Node.

2. SolusVM Traffic Shaping limits are not working : Cannot find device “eth0”

In SolusVM when Traffic Shaping limits are not working, even though it is enabled on the node’s settings page can lead to this error.

Also, we can see that the SolusVM back-end script responsible for traffic shaping fails to apply rules:

# php /usr/local/solusvm/includes/trafficloader.php --mode=all --debug=1
DELETING QDISC FROM eth0
ADDING QDISC TO eth0
Cannot find device "eth0"
DELETING QDISC FROM kvm105.0
ADDING QDISC TO kvm105.0
ADDING CLASS TO kvm105.0 WITH SPEED 100mbit CLASSID 1
ADDING QDISC TO kvm105.0 WITH HANDLE 1
ADDING CLASS TO eth0 WITH SPEED 100mbit CLASSID 1
Cannot find device "eth0"
ADDING QDISC TO eth0 WITH HANDLE 1

Cause

NIC device name on the node used by SolusVM is different than eth0

Steps to fix:

1. Firstly, we need to connect to the affected slave node via SSH

2. Then find the actual NIC device name using the following command:

# ip a

3. After that go to the node settings page in SolusVM and click Edit.

4. Here we need to set the correct NIC device name in the Network Interface field.

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Conclusion

In short, we saw how our Support Techs fix SolusVM: “cannot find device eth0” for our customers.