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Unused Linux Users: Delete or Keep Them?

Got unused or unknown system accounts on your Linux system? This article explains the different strategies and actions to take and keep the system healthy.

Summary

We get often the question what one should do with unused users on Linux. Everyone who looked in the /etc/passwd file will recognize them, strange usernames. A great example is UUCP, or Unix-to-Unix Copy. Once used for communication on direct lines, now another piece of history in our password files. The Options Before we make any decision on dealing with unused Linux accounts, we should look at the most obvious choices we have.

File permissions of the /etc/shadow password file

Got an issue with the file permissions of your /etc/shadow password file? Look no further and get it fixed.

Summary

The password files are an important cornerstone of the security of your Linux system. Commonly they are /etc/passwd and /etc/shadow, and installed by default. Sometimes we receive questions what the right permissions of these files should be. Therefore this blog post to have a look at the file permissions (and ownership) of both files. Passwd file The password file stores local accounts of the system. It is a readable text file and uses colons (:) to separate the fields.

Password Security with Linux /etc/shadow file

Learn the structure of the /etc/shadow file and what the underlying fields mean in this article. After reading, the file should be less cryptic than it was before.

Summary

Linux systems use a password file to store accounts, commonly available as /etc/passwd. For additional safety measures, a shadow copy of this file is used which includes the passwords of your users. Or actually hashed password, for maximum security. An example of a password entry in /etc/shadow may look like this: user1:$6$6Y/fI1nx$zQJj6AH9asTNfhxV7NoVgxByJyE.rVKK6tKXiOGNCfWBsrTGY7wtC6Cep6co9eVNkRFrpK6koXs1NU3AZQF8v/:16092:0:99999:7::: For proper display, let’s split this up in several fields: user1 $6$6Y/fI1nx$zQJj6AH9asTNfhxV7NoVgxByJyE.rVKK6tK 16092 0 99999 7 Field explanations Time to have a look what all these strings mean: