Snort is a free and open-source network intrusion detection system (NIDS) software that can operate on multiple operating systems, including Linux, UNIX, and Windows. It is designed to detect security threats in network traffic.
Snort has the following technical principles:
Packet capture: Snort captures network packets through network interfaces or pcap files.
Packet parsing: Snort parses the captured packets to extract the information required by network protocols.
Rule matching: Snort performs rule matching on each packet; if a match is successful, it indicates that there is a security threat in the packet.
Logging: Snort logs the matched packets, and can record different levels of log information based on different rules.
The main function of Snort is to detect network intrusion behaviors. It can identify and log various network attacks, such as DoS attacks, scanning, port scanning, sniffing, and information leakage. Once an intrusion is detected, Snort immediately notifies the administrator or security team so that they can take appropriate measures to respond.
The usage of Snort includes the following steps:
Installation: Download the software installation package and install the Snort software.
Configuration: Edit the Snort configuration file to set parameters such as network interface, rule path, and logs.
Download rules: Download the latest rule files from the Snort official website or third-party sites.
Start: Run the Snort software by entering commands in the terminal to start Snort.
Monitor network traffic: Snort listens to network traffic on the specified network interface and matches it according to the rules.
Handle alerts: Once a security threat is detected, Snort sends alert information to the administrator, who can take appropriate measures to respond.
Snortâs operation can be divided into the following two modes:
Signature detection mode
Signature detection mode, also known as rule-based detection mode, is the most commonly used detection method in Snort. It performs real-time detection and analysis of network communication data based on a preset rule library or user-defined rules. The rule library contains a series of detection rules, each of which includes matching parts and actions to be taken when a threat is discovered through that rule, such as alerting, dropping packets, and invoking other programs. Snort parses and analyzes packets, matching each received packet according to predefined rules; once a match is successful, it reports alert information.
Traffic analysis mode
Traffic analysis mode, also known as flow-based detection mode, uses traffic analysis techniques to detect abnormal network traffic. Snort defines and manages traffic; it does not detect traffic based on specific rules but analyzes the behavior, duration, and relationships between packets to determine if the traffic is abnormal. For example, when it detects that packets are being sent repeatedly, Snort considers this a DoS attack and issues an alert.
In addition to being an intrusion detection system (NIDS), Snort also has certain network auditing functions, which can audit network traffic and generate specific log records, helping administrators or security personnel understand the usage and security status of the network.
Some of Snortâs auditing functions include:
Traffic statistics: Snort can count traffic for different protocols, users, or devices, as well as the traffic situation of remote hosts and services.
IP address and port number statistics: Snort can count the number of packets for each IP address and port number, as well as their source and destination traffic.
Traffic capture: Snort can capture all packets transmitted over the network and log them.
Traffic tracking: Snort can track network traffic for specific users, ports, or protocols and perform record analysis, such as HTTP request analysis, SMTP email tracking, and FTP file transfers.
Through the above auditing functions, Snort can provide detailed monitoring and auditing of network traffic, allowing administrators to understand the usage and emergency response of the network, thereby enhancing network security.
A Sniffer is a type of network security tool that can capture and analyze network packets in real-time, helping system administrators and network security experts analyze events occurring in the network, identify network issues, and address security threats. Common use cases for Sniffer include network monitoring, debugging, and security auditing.
Unlike Snort, Sniffer is primarily used for analyzing and monitoring network traffic rather than intrusion detection. Sniffer can be installed on computers or embedded devices to sniff and analyze different network devices.
Using a Sniffer generally includes the following steps:
Installation and configuration: Choose a suitable Sniffer tool and install and configure it.
Capture packets: Start the Sniffer to begin capturing network packets and save them to a PCAP file.
Packet analysis: Use specialized packet analysis tools, such as Wireshark, to analyze and decode the captured packets to understand the information transmitted in the network traffic.
Address issues and threats: Identify network issues and threats based on the analysis results and take appropriate measures to address them.
Sniffers include both hardware and software types, with software Sniffers including:
NetXRay is a commercial network sniffer with advanced sniffing and analysis capabilities. It features a user-friendly graphical interface that can capture and visualize the flow of network packets in real-time, while also providing deep decoding of network and application layer protocols, traffic detection and filtering, and various analysis tools. NetXRay supports multiple operating system platforms, including Windows, Mac OS X, and Linux, and can capture packets from various protocols such as IP, TCP, UDP, ICMP, etc. Additionally, it supports deep decoding of application layer protocols like SSL/TLS, SSH, HTTP, POP3, IMAP, and LDAP, allowing for analysis of complex network protocols. Furthermore, NetXRay offers real-time statistics and reporting features to monitor and audit network traffic and performance. Users can export and share statistical data for analysis and communication.
Packetboy is a commercial network analysis tool that helps enterprises and organizations monitor and analyze network traffic. Packetboy provides an intuitive web interface that allows users to quickly view network data and events. It can decode and analyze various protocols, including TCP/IP, HTTP, SMTP, FTP, etc. Packetboy can capture network traffic and generate analysis reports to ensure network security. It also offers automated network tools, such as IP blacklisting, traffic monitoring, and anomaly detection, to help prevent intrusions and data leaks. Additionally, Packetboy provides comprehensive logging, allowing users to check historical data at any time. It can also monitor real-time statistics of network traffic to quickly identify losses and bottlenecks, helping to improve network performance.
NetMonitor is a powerful commercial network monitoring tool that can be used to monitor, analyze, diagnose, optimize, and debug network devices and applications. NetMonitor supports various operating systems and network architectures, including Windows, Linux, and Cisco IOS. NetMonitor can capture packets and display real-time network traffic, as well as perform detailed analysis of packets. It supports various protocols, including TCP/IP, HTTP, DNS, LDAP, etc. Users can use NetMonitor to diagnose network faults and performance bottlenecks, identify abnormal network traffic, and monitor network security issues.
WinPcap is an open-source network sniffing library that can be used by many network monitoring and analysis tools. WinPcap provides an API and drivers on computers to capture and analyze network packets on Windows operating systems. WinPcap can be used on Windows 98, ME, 2000, XP, Server 2003, Vista, Server 2008, Windows 7, and Windows 8, and it supports various network protocols and packet formats, such as Ethernet, IP, TCP, UDP, ICMP, etc. WinPcap can capture and log network packets while decoding network protocols and providing traffic statistics. Since WinPcap is an open-source network sniffing library, it is also used by many developers to write network monitoring and security tools, such as Wireshark and Nmap.
Wireshark is a cross-platform network protocol analyzer that can decode and analyze various protocols, supporting multiple operating system platforms such as Windows, Linux, and Mac OS X.
Hardware-type sniffers mainly refer to network analyzers or protocol analyzers, which are specialized devices for analyzing network traffic that support capturing and analyzing various network protocols and packets. Here are some common hardware-type sniffer products:
Fluke Networks offers various testing tools, including link analyzers and network traffic analyzers, for in-depth analysis and debugging of network traffic.
Riverbed provides network optimization and traffic analysis functions through various hardware devices, including SteelCentral Packet Analyzer and SteelCentral AppResponse.
Netscout produces various hardware network traffic analysis devices, including nGeniusONE and InfiniStream, for comprehensive analysis and optimization of networks.
Colasoft is also a professional provider of network analysis and security software, offering solutions that combine hardware and software, including Capsa Network Analyzer and CapMaker.