How to Keep Linux User Password Files Secure

How to ensure the security of Linux user password files

Linux system is a widely used operating system, so it is crucial to protect the security of user password files in the system important. The user password file stores the user's account information and encrypted passwords. If not properly protected, it may be subject to the risk of hacker attacks or information leakage. This article will introduce some methods to ensure the security of Linux user password files and give specific code examples.

1. Use appropriate permission settings
   The chmod command can be used to set permissions on files or directories. It is very important to ensure that the password file can only be read and written by the root user and that other users do not have permission to access it. The following is sample code to set password file permissions:

sudo chown root:root /etc/passwd
sudo chmod 600 /etc/passwd

2. Use password hash algorithm
   Linux system uses password hash algorithm to store user passwords, generally using SHA-256 or MD5. These algorithms can ensure that passwords are irreversible during storage, thereby improving password security. The following is a simple sample code:

mkpasswd -m sha-512

3. Change passwords regularly
   Changing user passwords regularly is an effective security measure. You can force users to change their passwords within a certain period by setting a password expiration time. The following is sample code to set the password expiration time:

chage -d 0 username

4. Using Password Policy
   Set a password policy to require users to create or change a password Always comply with certain rules, such as password length, complexity, validity period, etc. Password policies can be configured using PAM (Pluggable Authentication Modules) modules. The following is a sample code:

sudo apt-get install libpam-pwquality

5. Enable password complexity check
   Turning on password complexity check can prevent users from setting too many Simple passwords, thereby increasing password security. Add the following lines in the /etc/pam.d/common-password file:

password requisite pam_pwquality.so retry=3

Summary
The above are some methods to ensure the security of Linux user password files. By correctly setting permissions, using password hashing algorithms, changing passwords regularly, using password policies and password complexity checks, you can effectively protect user password files from being attacked or leaked. . In practical applications, it should also be configured flexibly according to needs and environment to protect the security of the system.

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