ICS-SCADA Exam Dumps - ECCouncil Network Security Questions and Answers

Port mirroring (also known as SPAN - Switched Port Analyzer) is considered one of the best ways to counter packet monitoring on a switch. This technique involves copying traffic from one or more switch ports (or an entire VLAN) to another port where the monitoring device is connected. Port mirroring allows administrators to monitor network traffic in a non-intrusive way, as it does not affect network performance and is transparent to users and endpoints on the network.References:

Cisco Systems, "Catalyst Switched Port Analyzer (SPAN) Configuration Example".

ICMP (Internet Control Message Protocol) is used in network devices, like routers, to send error messages and operational information indicating success or failure when communicating with another IP address.

An ICMP type 8 packet specifically is an "Echo Request." It is used primarily by the ping command to test the connectivity between two nodes.

When a device sends an ICMP Echo Request, it expects to receive an ICMP Echo Reply (type 0) from the target node. This mechanism helps in diagnosing the state and reachability of a network on the Internet or within a private network.

References

RFC 792 Internet Control Message Protocol: https://tools.ietf.org/html/rfc792

Internet Assigned Numbers Authority (IANA) ICMP Parameters:

IPsec uses two main protocols to secure network communications: Authentication Header (AH) and Encapsulating Security Payload (ESP).

Both AH and ESP use a Security Parameters Index (SPI), which is a critical component of their headers. The SPI is a unique identifier that enables the receiver to select the correct security association for processing incoming packets.

AH provides authentication and integrity, while ESP provides confidentiality, in addition to authentication and integrity. Both protocols use the SPI to manage these functions securely.

References

"IPsec Security Architecture," RFC 4302 (AH) and RFC 4303 (ESP).

"IPsec Explained," by Juniper Networks.

In the context of network security policies, a "Paranoid" stance typically means adopting a default-deny posture. This security approach is one of the most restrictive, where all access is blocked unless explicitly allowed.

A default deny strategy is considered best practice for securing highly sensitive environments, as it minimizes the risk of unauthorized access and reduces the attack surface.

This approach contrasts with more open stances such as Permissive or Promiscuous, which are less restrictive and generally allow more traffic by default.

References

"Network Security: Policies and Guidelines for Effective Network Management," by Jonathan Gossels.

"Best Practices for Implementing a Security Awareness Program," by Kaspersky Lab.

IPsec offers two modes of operation: Transport mode and Tunnel mode.

Transport mode in IPsec provides security for the payload (the message part) of each packet along the communication path between two endpoints.

In this mode, the IP header of the original packet is not encrypted; it secures only the payload, not protecting the headers. This means while the data is protected, information about the sender and receiver as contained in the IP header is not obscured.

References

"Security Architecture for IP," RFC 4301.

IPsec documentation, Internet Engineering Task Force (IETF).

The default size of a Windows Echo Request packet, commonly known as a ping request, is 28 bytes. This size is derived from the following components:

ICMP Header: The Internet Control Message Protocol (ICMP) header is 8 bytes.

IPv4 Header: The IP header for an IPv4 packet is typically 20 bytes.

Therefore, the total size of the default Windows Echo Request packet is 28 bytes (8 bytes for ICMP header + 20 bytes for IPv4 header).

References

"Ping (networking utility)," Wikipedia,Ping.

"ICMP Header Format," Cisco, ICMP Header.

In the Modbus protocol, the function code is used to tell the slave device what kind of action to perform, such as reading or writing data.

Modbus function codes specify the type of operation to be performed on the registers. For example, function code 03 is used to read holding registers, and function code 06 is used to write a single register.

Each function code is a single byte in size and is positioned at the start of the PDU (Protocol Data Unit) in the Modbus message structure, directly influencing how the slave interprets and executes the request.

References

"Modbus Application Protocol Specification V1.1b," Modbus Organization.

"The Modbus Protocol Explained," by Schneider Electric.

tcpdumpis a powerful command-line packet analyzer used primarily in UNIX and UNIX-like operating systems; it allows the capture and display of TCP/IP and other packets being transmitted or received over a network to which the computer is attached.

Unlike graphical tools like Wireshark,tcpdumpprovides raw output of the packet captures directly to the terminal or a specified file, making it ideal for deep dive network analysis, especially in environments where a graphical user interface is unavailable.

tcpdumpuses the libpcap library to capture packet data, which allows it to support a wide range of command-line options to filter and display packet information according to user needs.

References

"tcpdump manual page," by the Tcpdump Group.

"Practical Packet Analysis Using Wireshark to Solve Real-World Network Problems," by Chris Sanders, No Starch Press.

An Intrusion Detection System (IDS) is designed to monitor network or system activities for malicious activities or policy violations and can perform several functions:

Monitor:Observing network traffic and system activities for unusual or suspicious behavior.

Detect:Identifying potential security breaches including both known threats and unusual activities that could indicate new threats.

Respond:Executing pre-defined actions to address detected threats, which can include alerts or triggering automatic countermeasures.References:

Cisco Systems, "Intrusion Detection Systems".

Modbus TCP is a variant of the Modbus family of simple, networked protocols aimed at industrial automation applications. Unlike the original Modbus protocol, which runs over serial links, Modbus TCP runs over TCP/IP networks.

Port 502 is the standard TCP port used for Modbus TCP communications. This port is designated for Modbus messages encapsulated in a TCP/IP wrapper, facilitating communication between Modbus devices and management systems over an IP network.

Knowing the correct port number is crucial for network configuration, security settings, and troubleshooting communications within a Modbus-enabled ICS/SCADA environment.

References

Modbus Organization, "MODBUS Application Protocol Specification V1.1b3".

"Modbus TCP/IP – A Comprehensive Network protocol," by Schneider Electric.