[Network Security] 2.2 Intrusion Detection and Prevention System

Intrusion Detection and Prevention Systems (IDPS) are an important part of network security. They help us detect and stop cyberattacks. In this article, we will introduce in detail how IDPS works, its types, how to configure and use IDPS, and how to deal with threats discovered by IDPS.

1. What is an intrusion detection and prevention system?

Intrusion detection and prevention systems are devices or software that monitor the activity of a network or system, looking for possible malicious behavior or policy violations. When IDPS detects such behavior, it can take some action, such as sending a warning, blocking the activity, or sending a signal to other security devices such as firewalls.

For example, suppose a computer on your network suddenly starts sending large amounts of data externally. This could be malware trying to steal your data. If you have an IDPS, it can detect this abnormal behavior and take appropriate measures.

2. Types of intrusion detection and prevention systems

IDPS can be classified based on how they work and where they are located. Here are some common IDPS types:

1. Network Intrusion Detection System (NIDS) : NIDS is an IDPS that monitors the entire network traffic. It can detect network attacks such as denial-of-service attacks, scans, or botnets.

2. Host Intrusion Detection System (HIDS) : HIDS is an IDPS that monitors a single host (such as a server or workstation). It can detect host-level attacks such as malware, Trojans, or privilege escalation.

3. Network Intrusion Prevention System (NIPS) : NIPS not only detects network attacks, it also blocks them. For example, if NIPS detects a denial-of-service attack, it can block the attack traffic and protect your network.

4. Host Intrusion Prevention System (HIPS) : HIPS not only finds host-level attacks, it also blocks them. For example, if HIPS detects a piece of malware, it can block the malware's behavior and protect your host.

3. Working Principle of Intrusion Detection and Prevention System

The working principle of IDPS mainly relies on two technologies: feature matching and anomaly detection .

1. Signature Matching : Signature matching is the discovery of attacks by comparing network or system activity to known attack signatures, also known as signatures. For example, if a pattern of network traffic matches the pattern of a known denial-of-service attack, IDPS will consider it an attack.

2. Anomaly Detection : Anomaly detection detects attacks by comparing network or system activity to normal behavioral patterns. For example, if a computer suddenly starts sending large amounts of data, this may be an unusual behavior and therefore IDPS will consider this a possible attack.

4. Configuration of intrusion detection and prevention systems

Configuration of IDPS mainly involves defining the normal behavior patterns of your network or system and selecting the attack signatures you want to detect.

For example, you may need to define the normal traffic patterns of your network, such as traffic size, frequency, destination, etc. You may also need to select the attack signatures you want to detect, such as known malware signatures, attack tool signatures, etc.

In addition, you also need to configure the IDPS response policy. For example, when the IDPS detects a possible attack, it should send a warning, block the activity, or send a signal to other security devices.

Snort intrusion detection system configuration example:

Snort is an open source NIDS that uses a language called rules to define attack signatures. Here are some examples of Snort rules:

# 检测PING扫描
alert icmp any any -> $HOME_NET any (msg:"ICMP PING"; icode:0; itype:8;)

# 检测SSH暴力破解
alert tcp any any -> $HOME_NET 22 (msg:"SSH Brute Force Attempt"; flags:S;)

# 检测SQL注入攻击
alert tcp $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"SQL Injection Attempt"; pcre:"/(\%27)|(\')|(\-\-)|(\%23)|(#)/i";)

5. Handle warnings from intrusion detection and prevention systems

When your IDPS detects a possible attack, you need to take a few steps to acknowledge and handle the alert.

1. Confirmation : First, you need to confirm whether the warning is actually an attack. Sometimes, IDPS may issue false positives; for example, it may mistake normal network traffic for an attack.

2. Analysis : If you confirm that this is an attack, you need to analyze the nature and impact of the attack. For example, what type of attack is this? What is it trying to do? What systems does it affect?

3. Response : Based on the results of your analysis, you need to take some response actions. For example, you may need to block attack traffic, clean affected systems, or update your security policies.

6. Challenges and future of intrusion detection and prevention systems

Although IDPS is an important tool for network security defense, it also faces some challenges, such as how to handle encrypted traffic, how to prevent zero-day attacks, how to handle a large number of warnings, etc. In addition, with the development of cloud computing and the Internet of Things, we need new IDPS technology to protect these new environments and devices.

In the future, we may see smarter, more flexible IDPS that can automatically learn and adapt to new threats while also being easier to configure and manage.

in conclusion

Intrusion detection and prevention systems are an important part of network security. They can help us detect and prevent network attacks. By understanding how IDPS works, its types, how to configure and use IDPS, and how to deal with threats identified by IDPS, we can better protect our networks and systems.