10 Linux commands you must master!

As an experienced Linux operation and maintenance engineer, ensuring the security of the server is my top priority. The Linux system provides a variety of tools to help us ensure the security of the server. This article will share 10 essential Linux commands that can greatly improve your work efficiency and server security.

　1. passwd command: change user password

In order to protect the security of the server, it is necessary to change the password regularly. You can use the passwd command to change user passwords.

　$ passwd

　2. su command: switch user identity

Use the su command to switch to other users without exiting the current user, which helps limit access rights or perform specific tasks.

　$ su – username

　3. chmod command: modify file permissions

Protecting permissions on sensitive files and directories is critical. Use the chmod command to restrict access to files and directories.

　$ chmod 600 /path/to/file

　$ chmod 700 /path/to/directory

　4. chown command: modify file owner

The chown command can be used to modify the owner of a file or directory. Ensure that only authorized users can modify sensitive files.

　$ chown owner:group /path/to/file

　5. iptables command: configure firewall rules

　The iptables command is used to configure the firewall rules of the Linux system, which can restrict network access and improve the security of the server.

　$ iptables -A input -p tcp –dport 22 -j DROP

6. fail2ban command: prevent brute force cracking

　fail2ban is a tool used to protect servers from brute force attacks. It monitors login log files and temporarily blocks access from the IP in question when multiple failed login attempts are detected.

　$ sudo apt-get install fail2ban

　7. logrotate command: log rotation

Log files can occupy a lot of disk space, so it is necessary to use the logrotate command to rotate logs regularly.

　$ sudo logrotate /etc/logrotate.conf

　8. netstat command: check network connection status

Use the netstat command to view the network connection and port status on the current server. This helps detect unusual network activity.

　$ netstat -tuln

　9. Find command: Find files

Use the find command to search for files on the server and perform various operations. This is useful for finding potential security issues or malicious files.

　$ find /path/to/search -name “filename”

　10. ssh command: secure remote login

　SSH is a secure remote login protocol that can establish encrypted connections. Ensure that only authorized users can log into the server via ssh.

　$ ssh user@hostname

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