Etc

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.

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.

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 empty empty Field explanations Time to have a look what all these strings mean: