The encrypted passwords and other information such as password expiry information (the password aging information) are stored in /etc/shadow file. However, normal user cannot access the /etc/shadow file directly. For example, try out following cat command:
$ cat /etc/shadow
Output:
cat: /etc/shadow: Permission denied
You can only access this file via few commands such as passwd. Login as root user and execute cat command on /etc/shadow file:
$ su -
Password:
# cat /etc/shadow
Output:
root: $1$s83Ugoff$EDT83WAAFpCQHWDp07E9Ux:0:99999:7::: daemon:*:13031:0:99999:7::: bin:*:13031:0:99999:7:::
Each entry in /etc/shadow is divided into following fields:
- Login name
- Encrypted password
- Days since Jan 1, 1970 that password was last changed
- Days before password may be changed
- Days after which password must be changed
- Days before password is to expire that user is warned
- Days after password expires that account is disabled
- Days since Jan 1, 1970 that account is disabled
Please note that FreeBSD uses /etc/master.shadow file.
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