Secrets to Linux Server Security: Master These Essential Commands

Secrets to Linux server security: Master these must-have commands

Summary: Securing a Linux server requires a comprehensive approach that includes proficiency in the use of some must-have commands is very important. This article will introduce several commonly used Linux commands and provide code examples to help administrators improve server security.

1. Firewall (Firewall)
   The firewall is the first line of defense to protect server security. In Linux, use the iptables command to configure firewall rules. The following are some commonly used iptables commands and their examples:

1.1 Enable firewall

sudo systemctl start iptables

1.2 Add rules

sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 443 -j ACCEPT
sudo iptables -A INPUT -j DROP

1.3 View firewall rules

sudo iptables -L -n

2. SSH login management
   SSH is a common tool for remote login between administrators and servers, and it is also a key point in server security. Here are a few ways to secure SSH:

2.1 Disable root remote login

sudo nano /etc/ssh/sshd_config
PermitRootLogin no

2.2 Use a key pair for authentication

ssh-keygen -t rsa

2.3 Change SSH Port

sudo nano /etc/ssh/sshd_config
Port 2222

3. Fine-grained file permission control
   Properly configured file permissions can prevent unauthorized access and modification. The following are several commonly used commands:

3.1 Change file permissions

chmod 600 file.txt  # 只有所有者拥有读写权限
chmod 644 file.txt  # 所有者拥有读写权限，其他用户只读权限
chmod +x script.sh  # 添加可执行权限

3.2 Change file owner

sudo chown username:groupname file.txt

4. Package Management
   Timely Updating software packages is key to keeping your server secure. The following is an example of using the apt command to manage packages:

4.1 Update package list

sudo apt update

4.2 Upgrade all installed packages

sudo apt upgrade

4.3 Search Specific software package

apt search package_name

5. Log management
   Log files record various activities of the system, including security-related information. The following are some commonly used commands:

5.1 View system log

tail -f /var/log/syslog

5.2 View login log

tail -f /var/log/auth.log

5.3 View error log

tail -f /var/log/nginx/error.log

Comprehensive As mentioned above, proficient use of these necessary commands is the key to protecting the security of Linux servers. Administrators should regularly update software packages, configure firewall rules, restrict SSH access, and set file permissions correctly. At the same time, it is also very important to regularly audit system and login logs, as well as other security-related records. Armed with this knowledge, administrators will be better able to secure servers and improve system stability and performance.

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