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The Modbus protocol was developed by Modicon, now a brand of Schneider Electric.

It was originally designed in 1979 for use with its programmable logic controllers (PLCs) in industrial applications.

Modbus is a serial communications protocol that has become a de facto standard communication protocol and is now commonly used to connect industrial electronic devices. The main reasons for its use are its simplicity and the fact that it is open-source, which allows manufacturers to build their own implementations of the standard.

References

"Modbus Protocol Reference Guide," Modicon, Inc., 1979.

"A Guide to the Modbus Protocol," Schneider Electric.

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".

The IT Security Model commonly refers to the CIA Triad, which stands for Confidentiality, Integrity, and Availability.

An attack on "Availability" is aimed at disrupting the normal functioning and access to data or resources in a network. This type of attack can include actions such as DDoS (Distributed Denial of Service), where overwhelming traffic is sent to a system to make it unresponsive.

The main goal of attacks on availability is to prevent legitimate users from accessing systems or information, which can have significant implications for business operations and security.

References

Understanding the CIA Triad in Cybersecurity:

Denial of Service – What it is and how to prevent it:

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:

Internet Assigned Numbers Authority (IANA) ICMP Parameters: