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

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Jul 05, 2023 pm 06:24 PM

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

In the era of network security, protecting servers from potential attacks is crucial. CentOS, as a widely used operating system, provides some methods to disable unsafe protocols and services and increase server security. This article will introduce some methods to set up CentOS systems to disable unsafe protocols and services, and provide corresponding code examples.

1. Disable unsafe protocols

Disable Telnet protocol:

Telnet is a clear text transmission protocol that is easily eavesdropped by hackers and is not Provide any encryption capabilities. In order to disable the Telnet protocol, we need to modify the /etc/xinetd.d/telnet file:

vi /etc/xinetd.d/telnet

Change the value of the disable field to yes:

disable = yes

Save and exit the file, and then restart the xinetd service :

service xinetd restart

Disable FTP protocol:

The FTP protocol is also a clear text transmission protocol and is easily eavesdropped and hijacked by hackers, so it is no longer recommended. In order to disable the FTP protocol, we need to modify the /etc/xinetd.d/vsftpd file:

vi /etc/xinetd.d/vsftpd

Change the value of the disable field to yes:

disable = yes

Save and exit the file, and then restart the xinetd service :

service xinetd restart

Disable rsh protocol:

rsh protocol is a remote shell protocol based on clear text transmission, which is vulnerable to man-in-the-middle attacks and information theft. In order to disable the rsh protocol, we need to modify the /etc/xinetd.d/rsh file:

vi /etc/xinetd.d/rsh

Change the value of the disable field to yes:

disable = yes

Save and exit the file, and then restart the xinetd service ：

service xinetd restart

2. Disable unsafe services

Disable Sendmail service:

Sendmail is a commonly used mail transfer agent, but due to It has security vulnerabilities and can easily be exploited by hackers to conduct malicious acts. In order to disable the Sendmail service, we need to execute the following command:

chkconfig sendmail off
service sendmail stop

Disable the Telnet service:

In addition to disabling the Telnet protocol, we also need to disable the Telnet service to ensure that the server does not Unauthenticated remote access channels will be opened. In order to disable the Telnet service, we need to execute the following command:

chkconfig telnet off
service telnet stop

Disable the FTP service:

In addition to disabling the FTP protocol, we also need to disable the FTP service to ensure that the server does not Anonymous user access will be opened. In order to disable the FTP service, we need to execute the following command:

chkconfig vsftpd off
service vsftpd stop

3. Other security settings

Ensure that the OpenSSH protocol configuration is secure:

The SSH protocol is A secure remote connection protocol for remote login to servers. In order to ensure the security of the OpenSSH protocol configuration, we need to modify the /etc/ssh/sshd_config file:

vi /etc/ssh/sshd_config

Find the following line and change its value to no:

#PermitRootLogin yes

Save and exit the file, and then restart SSH service:

service sshd restart

Set firewall rules:

The CentOS system has the iptables firewall enabled by default. In order to increase the security of the server, we can set some firewall rules. Here are some basic examples of firewall rules:

Allow SSH connections:

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

Allow HTTP connections:

iptables -A INPUT -p tcp --dport 80 -j ACCEPT

Disallow all other connections:

iptables -A INPUT -j DROP

Above These are some methods to set up CentOS systems to disable unsafe protocols and services. By disabling unsafe protocols and services, we can improve the security of the server and reduce potential attack risks. Before taking any action, make sure you understand the impact of each action and back up important data.

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