How to set up a CentOS system to disable insecure network protocols and services

How to set up CentOS system to disable unsafe network protocols and services

Introduction:
Network security is an important issue in the current information age. As a widely used operating system, CentOS also needs We take some measures to enhance network security. This article will describe how to set up a CentOS system to disable insecure network protocols and services to reduce the system's attack surface, and provide some code examples.

1. Disable unsafe network protocols

1. Disable Telnet protocol
   Telnet is an unsafe remote login protocol because it does not transmit data when transmitting data. Encrypt. We can disable the Telnet protocol by modifying the network configuration file of the CentOS system. The specific steps are as follows:
   a. Open the /etc/securetty file, find and comment out the following line:

   # pts/0
   # pts/1
   # pts/2

   b. Open the /etc/xinetd.d/telnet file, and change the disable in the following line to yes:

   ...
   disable = yes
   ...

   c. Use the following command to restart the xinetd service:

   systemctl restart xinetd

2. Disable FTP protocol
   FTP protocol is a file transfer protocol for clear text transmission. There are security risks. We can disable the FTP service by modifying the vsftpd configuration file. The specific steps are as follows:
   a. Use the following command to edit the /etc/vsftpd/vsftpd.conf file:

   vi /etc/vsftpd/vsftpd.conf

   b. Change the value of the following line to NO:

   anonymous_enable=NO

   c. Use the following command to restart the vsftpd service:

   systemctl restart vsftpd

   2. Disable unsafe network services

3. Disable Telnet service
   In addition to disabling the Telnet protocol, we can also pass Modify the service configuration file of the CentOS system to disable the Telnet service. The specific steps are as follows:
   a. Use the following command to edit the /etc/xinetd.d/telnet file:

   vi /etc/xinetd.d/telnet

   b. Change disable in the following line to yes:

   disable = yes

   c. Use the following command to restart the xinetd service:

   systemctl restart xinetd

4. Disable FTP service
   In addition to disabling the FTP protocol, we can also disable the FTP service by modifying the service configuration file of the CentOS system. The specific steps are as follows:
   a. Use the following command to edit the /etc/services file:

   vi /etc/services

   b. Comment out the following line:

   ftp             21/tcp          # File Transfer Protocol

   c. Use the following command to restart the vsftpd service:

   systemctl restart vsftpd

   Conclusion:
   By disabling unsafe network protocols and services, we can reduce the attack surface of the system and improve the network security of the CentOS system. Combined with other network security measures, such as using firewalls, regularly updating systems, etc., our systems can be effectively protected from network attacks. I hope this article will help you set up network security on your CentOS system.

Reference:

1. CentOS official documentation - https://www.centos.org/
2. Red Hat Enterprise Linux 7 Security Guide - https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/security_guide/index.html

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