How Do You Get a USB-to-Ethernet Cable to Work with Linux?

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Problem
You connect a USB convertor (for a wired ethernet cable) to your Linux laptop. It isn’t working as a plug-and-play device. What could be wrong?

Solution
1. In the GUI on the Linux desktop, go to “Settings” or “Control Settings”. 2. Then go to “Network”.
3. Click a plus sign “+” (to add a new profile).
4. On the Identity tab,

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How Do You Troubleshoot “…quota: Cannot open quotafile //aquota.user: Permission denied”?

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Problem scenario
You run a quota command. But you get “quota: Cannot open quotafile…” //aquota.group or //aquota.user … “Permission denied.”

What should you do?

Possible Solution #1
Maybe you do not have permissions. Can you run it with “sudo “?

If you run it with sudo and just see the quota governing the root user, then try running a command like this:

sudo quota -u jdoe
# Replace “jdoe” with the non-root user

You may want to find the relevant files with commands like this:

sudo find / -name aquota.group
sudo find / -name aquota.user

Possible Solution #2
This assumes you have the chattr utility installed;

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How Do You Fix Apache Kafka when It Hangs?

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Problem scenario
You try to start the Apache Kafka service. You get this:

[2021-07-25 12:15:36,687] INFO [Group Metadata Manager on Broker 1]: Finished loading offsets from [__consumer_offsets,24] in 123456789 milliseconds.

GroupMetadataManager…Finished loading offsets and group metadata from __consumer_offsets…seconds spent in the scheduler. (kafka.coordinator.group.GroupMetadataManager)

It just hangs and will not progress. What do you do?

Solution
Whenever a command hangs that is supposed to start a service,

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Why Are Ubuntu Versions (the Corresponding Integer Number Values) Usually Even?

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Problem scenario
You are curious why the odd versions of Ubuntu get so little attention. Why is this?

Answer
Even versions get long term support. If you are uncertain which version of Ubuntu to install, we recommend the highest even number release. As of February 2022, this is Ubuntu 22.x.

See this for more information: https://ubuntu.com/about/release-cycle

Be advised that odd versions will have an end of life that is sooner than the end of life for the previous even version.

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How Do You Fix “Cannot find any quota file…” or “Cannot guess” after Running a Quota-Related Command?

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Problem scenario
You run a command like edquota, but you get an error about not finding a quota file to work on or no file systems with a quota have been detected. Or maybe you ran a quotacheck command and got an error about not being able to guess a format from a filename.

What should you do?

Solution

  1. Can you move the aquota.group or aquota.user file at the root of the file system to a backed up version (e.g.,

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How Do You Troubleshoot a VirtualBox VM saying “failed unmounting /cdrom”?

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Problem scenario
In VirtualBox you are trying to boot a VM, but you get “failed unmounting /cdrom”. You see no option to unmount or remove the CD ROM. What should you do?

Possible Solution #1
Restart VirtualBox. Close it. Reopen it.

Possible Solution #2
Reboot the computer hosting/running VirtualBox.

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How Do You Make Changes to an /etc/fstab File when It Is Read Only?

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Problem scenario
You cannot make changes to an /etc/fstab file. It is read only. What should you do?

Possible Solution #1
If your /etc/fstab file is messed up (through manual changes to it), and your system boots it as read only, can you run a command like this?

sudo mount -o remount,rw /dev/mapper/foobar /directory/to/be/mounted

If you run “sudo cat /etc/fstab” you will see lines like this:

/dev/mapper/foobar / ext4 defaults 1 1

(If you saw the above,

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Is It a Best/Recommended Practice to Not Allow Desktop Clipboard Pastes for Password Fields on a Website?

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Problem scenario
You think a website field for a password should allow a password to be pasted in. This could make the users not copy the password. Some hackers exploit memory/RAM. Should you avoid allowing a password to be pasted in?

Solution
Traditionally confirmation password fields did not allow pasting (with control-v) from the clipboard. Now NIST is saying you can do this: https://pages.nist.gov/800-63-FAQ/

Some people think it is not ideal to have sensitive information in RAM.

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How Are Backoff Strategies (with Client Retries) Helpful?

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Question
Sometimes a client attempts to connect to or use an application. Sometimes a Kubernetes Pod is being created and tries to pull down an image. Sometimes a network device tries to establish a connection to an endpoint. These attempts can initially fail. Retries can be attempted in rapid succession. To mitigate excessive attempts in a short amount of time (to not waste resources or cause a denial-of-service attack),

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