How to use gateway IDS to secure the internal network of CentOS servers

How to use gateway IDS to protect the security of the CentOS server's internal network

Abstract: With the increasing number of network attacks, protecting the security of the server's internal network has become particularly important. This article will introduce how to use gateway IDS (Intrusion Detection System) to protect the security of the CentOS server's internal network. We will monitor network traffic by configuring a gateway IDS and use a rule-based firewall to block malicious traffic from entering the internal network. The article will also include some sample code to help readers better understand and implement these security measures.

1. Introduction
   Gateway IDS is a system that detects and blocks malicious activity by monitoring and analyzing network traffic. It monitors network behavior and traffic to identify and report possible attacks. By placing the gateway IDS at the gateway between the internal network and the external network, we can effectively protect the security of the server's internal network.
2. Install and configure gateway IDS
   First, we need to install and configure a gateway IDS software, such as Suricata. Suricata is a powerful open source IDS/IPS system that runs on CentOS servers.

(1) Install Suricata:
$ sudo yum install epel-release
$ sudo yum install suricata

(2) Configure Suricata:
$ sudo vi /etc/suricata/suricata.yaml
In the configuration file, we can customize the behavior of Suricata by defining rule sets, enabling logging, configuring alarms, etc.

3. Configure firewall rules
   It is very important to configure firewall rules on the gateway to prevent malicious traffic from entering the server intranet. We can use iptables or nftables to achieve this. The following is an example of using iptables:

(1) Create a new iptables chain:
$ sudo iptables -N IDS

(2) Will log the gateway IDS Traffic is directed to this chain:
$ sudo iptables -A INPUT -j IDS

(3) Configure rules on the IDS chain:
$ sudo iptables -A IDS -m conntrack --ctstate ESTABLISHED ,RELATED -j ACCEPT
$ sudo iptables -A IDS -m conntrack --ctstate INVALID -j DROP
$ sudo iptables -A IDS -p tcp --dport 22 -m recent --name ssh --set -m comment --comment "Allow SSH"
$ sudo iptables -A IDS -p tcp --dport 22 -m recent --name ssh --rcheck --seconds 60 --hitcount 4 -j DROP

The meaning of the above rules is: allow established and related connections to pass through, discard invalid connections, and prohibit SSH connections if 4 consecutive SSH connections are triggered within 60 seconds.

4. Log analysis and alarm
   Setting up gateway IDS can generate a large amount of logs. We can detect potential attack activities by analyzing these logs and setting alarms. The following is a code example that uses a Python script to read and analyze Suricata logs:

import sys

logfile_path = '/var/log/suricata/eve.json'

def analyze_logs():
    with open(logfile_path, 'r') as logfile:
        for line in logfile:
            # 在这里进行日志分析和报警的逻辑
            pass

if __name__ == '__main__':
    analyze_logs()

By writing appropriate logic, we can detect abnormal traffic, malicious IPs and other potential attack activities, and promptly Sound an alarm.

5. Regularly update the rule set and software
   In order to maintain the security of the server intranet, it is important to regularly update the rule set and software of the gateway IDS. We can update Suricata's ruleset using command line tools or configuration files. In addition, we should frequently update the operating system and related software on the server to fix potential vulnerabilities.

Conclusion:
By using gateway IDS and configuring firewall rules, we can protect the security of the CentOS server's internal network. Just installing an IDS system is not enough, we also need to regularly update the rule set, monitor logs and provide timely alarms. Only through comprehensive security measures can the server intranet be effectively protected from the threat of network attacks.

Reference materials:

• Suricata official documentation: https://suricata.readthedocs.io/
• iptables documentation: https://netfilter.org/documentation /

(Note: The sample code in this article is for reference only. Please adjust and test according to the actual situation in the specific environment.)

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