How to use a gateway firewall to protect your CentOS server's network security

How to use gateway firewall to protect the network security of CentOS servers

In today's highly interconnected network environment, server network security issues have become particularly important. As a common and powerful protection measure, gateway firewall can help us protect the network security of CentOS servers. This article will introduce how to use gateway firewall to protect CentOS server.

1. Install and configure the gateway firewall

1. First, we need to install a gateway firewall software package. In CentOS, the commonly used gateway firewall software package is iptables. Use the following command to install iptables:

sudo yum install iptables

2. After the installation is complete, we need to configure iptables rules. In CentOS, iptables rules are stored in the /etc/sysconfig/iptables file. We can use the following command to configure:

sudo vi /etc/sysconfig/iptables

3. After opening the iptables configuration file, you can see some default rules. We can add new rules as needed to protect the server. The following are several commonly used rule examples:

# 允许SSH访问
-A INPUT -p tcp --dport 22 -j ACCEPT

# 允许HTTP访问
-A INPUT -p tcp --dport 80 -j ACCEPT

# 允许HTTPS访问
-A INPUT -p tcp --dport 443 -j ACCEPT

# 允许Ping访问
-A INPUT -p icmp -j ACCEPT

# 其它规则（根据需要添加）

4. After adding the rules, you need to save and close the file. After saving, restart the iptables service to make the configuration take effect:

sudo systemctl restart iptables

2. Configure gateway firewall related settings

1. In order to improve the security of the server, we can disable some dangerous network services. In CentOS, you can use the following command to check and shut down unnecessary services:

sudo systemctl list-unit-files | grep enabled

2. After disabling unnecessary services, we can also limit the number of network connections to prevent denial of service attacks (DDoS). The following is an example of a rule that limits the maximum number of connections per IP address:

# 限制每个IP地址最大连接数为5
-A INPUT -p tcp -m connlimit --connlimit-above 5 -j REJECT --reject-with tcp-reset

3. Use port forwarding to protect the server

1. Port forwarding is a commonly used network security technology that can Requests from the external network are forwarded to the specified port on the server. The following is an example of a commonly used port forwarding rule:

# 将外部的80端口请求转发到内部服务器的8080端口
-A PREROUTING -t nat -p tcp --dport 80 -j REDIRECT --to-port 8080

2. After configuring the port forwarding rule, save and close the iptables configuration file. After restarting the iptables service, the port forwarding rules will take effect.

4. Monitor and update gateway firewall rules

In order to ensure the network security of the server, we need to regularly monitor and update gateway firewall rules. The following are some common ways to monitor and update rules:

1. Use log analysis tools, such as fail2ban, etc., to monitor login failure logs and automatically block malicious IP addresses.

2. Regularly check and upgrade the firewall software package installed on the server to obtain the latest security patches.

3. Conduct regular security audits to discover and repair possible security vulnerabilities.

5. Summary

By using the gateway firewall, we can effectively protect the network security of the CentOS server. Properly configuring and using iptables rules, limiting the number of network connections, port forwarding and other technical means can enhance the network security of the server. But it should be noted that security work is a continuous process, and we need to regularly monitor and update gateway firewall rules to maintain the network security of the server.

The above is a detailed introduction on how to use gateway firewall to protect the network security of CentOS server. I hope this article will be helpful to server administrators in their network security work.

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