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

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.