Learn to use command line tools: essential skills to improve server security

Learn to use command line tools: essential skills to improve server security

With the rapid development of the Internet, server security has become particularly important. As server administrators, we must learn to use command line tools to improve server security. This article will introduce some commonly used command line tools and give some code examples to help readers better understand how to use these tools to protect servers.

1. SSH (Secure Shell)
   SSH is a protocol for remote login to the server through encryption. It can effectively prevent malicious users from intercepting your login credentials. We can use the command line tool ssh to connect to the server.

Sample code:

ssh username@server_ip

In the above example, we can replace username with your username and server_ip with the IP address of the server. With this command, you will be able to remotely log in to the server through the command line interface.

2. iptables
   iptables is a tool used to manage firewall rules on Linux operating systems. By using iptables, we can configure the server's firewall rules to restrict access and prevent malicious intrusions.

Sample code:

iptables -A INPUT -p tcp --dport 22 -j DROP

In the above example, we can use this command to prohibit access to the server through the SSH protocol. Doing this will effectively prevent malicious users from trying to log into your server.

3. Fail2Ban
   Fail2Ban is a tool used to prevent brute force attacks. When an IP address fails to log in multiple times within a short period of time, Fail2Ban will automatically add the IP address to the firewall rules and prohibit access by the IP address.

Sample code:

fail2ban-client set sshd banip ip_address

In the above example, we can use this command to add a specific IP address to Fail2Ban’s block list.

4. Nmap
   Nmap is a tool for network scanning and security assessment. By using Nmap, we can discover unsafe ports and services on the server and take timely measures to fix these problems.

Sample code:

nmap -p 80,443 server_ip

In the above example, we can use this command to scan ports 80 and 443 on the server, which are usually the ports used by web servers. In this way, we can discover and fix possible security vulnerabilities in a timely manner.

5. AIDE
   AIDE is a tool for checking the integrity of files and directories. By using AIDE, we can monitor changes in files and directories on the server and discover potentially tampered or deleted files in a timely manner.

Sample code:

aide -c /etc/aide.conf --check

In the above example, we can use this command to check the integrity of the files and directories specified by the configuration file /etc/aide.conf .

Summary:
By learning to use command line tools, we can effectively improve the security of the server. This article introduces some commonly used command line tools and gives some code examples to help readers better understand how to use these tools to protect servers. However, security is a persistent theme, and we should continue to learn and adapt to new security challenges to ensure that servers operate safely.

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