An intrusion detection system (IDS) is a type of security software that is designed to detect and alert on malicious or unauthorized activities on a network or computer system. IDSs can be divided into two main categories: network-based IDSs (NIDS) and host-based IDSs (HIDS).
Network-based IDSs (NIDS) are placed on the network to monitor all incoming and outgoing network traffic. NIDSs use a variety of methods to detect malicious activity, such as signature-based detection, anomaly-based detection, and stateful protocol analysis. Signature-based detection looks for known patterns of malicious activity, while anomaly-based detection looks for unusual patterns in the network traffic. Stateful protocol analysis monitors the state of the connection to detect any anomalies in the network traffic.
For example, a NIDS could inspect all traffic coming to the network and check if it matches with a predefined rule of a known attack, and if that’s the case it would raise an alert.
Host-based IDSs (HIDS) are installed on individual computers or servers to monitor activity on that specific host. HIDSs can monitor a variety of activity on the host, including system calls, file access, and system logs. HIDSs use methods similar to NIDSs, such as signature-based detection and anomaly-based detection, to detect malicious activity.
For example, a HIDS could monitor the system logs for any suspicious activity, such as a user creating a new account with root privileges, and if that’s the case it would raise an alert.
Both NIDSs and HIDSs can be configured to take a variety of actions in response to detected malicious activity, such as logging the event, blocking the malicious traffic, or alerting the administrator.
It’s important to note that IDSs are not a silver bullet and they can’t prevent all attacks, an IDS can only detect and alert on malicious activity, but it can’t stop the attack from happening. Therefore, it’s important to have other security measures in place, such as firewalls, intrusion prevention systems (IPS), and endpoint protection, to provide a comprehensive defense against cyber attacks.
In summary, An intrusion detection system (IDS) is a type of security software that is designed to detect and alert on malicious or unauthorized activities on a network or computer system. IDSs can be divided into two main categories: network-based IDSs (NIDS) and host-based IDSs (HIDS), and they use a variety of methods to detect malicious activity, such as signature-based detection, anomaly-based detection, and stateful protocol analysis. IDSs are important to have in place, but they’re not a silver bullet, it’s important to have other security measures in place, such as firewalls, intrusion prevention systems (IPS), and endpoint protection, to provide a comprehensive defense against cyber attacks.