How to set up your CentOS system to prevent automatic updates of malicious programs

How to set up CentOS system to prevent automatic updates of malicious programs

Summary: Automatic updates of malicious programs may bring serious security threats to our CentOS system, so we need to take appropriate measures to prevent It updates automatically. This article will introduce how to set up a CentOS system to prevent automatic updates of malicious programs and give corresponding code examples.

1. Disable the automatic update service
   The CentOS system will automatically use the yum service to update software packages by default. We can disable the automatic update service by modifying the yum configuration file.

First, use vim or other editor to open yum's configuration file /etc/yum.conf:

sudo vi /etc/yum.conf

Then, find the following line:

# Uncomment to enable exclude list for a specific repo (disable for all repos)
#exclude=php*

In Add the comment symbol "#" in front of these two lines to change to the following form:

# Exclude list for a specific repo (disable for all repos)
#exclude=php*

Save the file and exit.

2. Set firewall rules
   In order to further protect the system from malicious programs, we can also set firewall rules to prohibit unauthorized network access.

First, use the iptables command to view the current firewall rules:

sudo iptables -L

Then, use the iptables command to add the corresponding rules to prohibit access to the automatic update service:

sudo iptables -A OUTPUT -m owner --uid-owner yum -j DROP

The above command will prohibit requests from user "yum" as the owner from passing the OUTPUT chain. It is assumed here that the yum user is used to execute the automatic update service. If you use another user, please modify the user name in the command accordingly.

Finally, use the service command to restart the firewall to make the settings take effect:

sudo service iptables restart

3. Regularly check the system security status
   Regularly checking the system security status is very important, we can use some Tools to scan your system for malicious programs and vulnerabilities.

Among them, ClamAV is a very popular open source anti-virus software that can be used to scan the system for malicious programs:

sudo yum install -y clamav
sudo freshclam
sudo clamscan -r /

The above command will install ClamAV and scan the entire system.

In addition, OpenVAS is a comprehensive vulnerability assessment system that can be used to scan security vulnerabilities in the system:

sudo yum install -y openvas
sudo openvas-setup
sudo openvas-scan

The above command will install OpenVAS and scan the system for security vulnerabilities.

Summary: By disabling the automatic update service, setting firewall rules and regularly checking the system security status, we can effectively prevent automatic updates of malicious programs and improve system security. During the setup process, we need to make adjustments according to the actual situation, and regularly update the system and security patches to ensure the security of the system.

It should be noted that the method provided in this article is only a preventive measure and cannot guarantee complete prevention of automatic updates of malicious programs. Before using the code examples, please make sure that you have a certain understanding of the system's operation and operate with caution to avoid causing other problems.

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