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National Instruments software packages and embedded hardware targets take advantage of network communication for application deployment, remote control of applications or instruments, transferring data, accessing and hosting web servers and services, and more. When using National Instruments network-enabled products with hardware or software firewalls, information about individual network port access may be needed to permit communication. This tutorial briefly explains the networking settings associated with performing common tasks using NI products, including the default TCP/UDP ports used and how to reconfigure these ports (if possible).

1. Introduction to Network Ports and Firewalls

On modern computer systems, network communication including web page traffic, file transfers, emails, and more can be logically divided into different layers; this is known as the OSI Model. One layer, known as the network layer, is responsible for successfully routing network traffic, and providing error detection and diagnostic capability. The main network layer protocol used for both local network and Internet communication is known as Internet Protocol (IP). Another layer, known as the transport layer, is responsible for providing end-to-end communication services for applications. Two of the most common transport layer protocols are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).

In order for a piece of network traffic to reach an application on a remote system, it must contain two key pieces of information: an address for the computer(s) that should receive the traffic (this is referred to as an IP address when using the IP protocol), and a destination port number for the application on the remote system(s) that should process the data. The IP address of the computer transmitting the data or request is also sent along with a source port number used by the originating application. In practice, each transport layer protocol (e.g. TCP, UDP) allows for up to 65, 535 ports that applications can use.

If an application on a given computer is accepting data, or "listening" on a given port, then the potential exists for that application to receive network data and do something based on that data. In this way, network traffic can affect the operation of a system up to the extent that an application allows. To reduce the effect that network traffic can have on a computer's operation, both networking equipment and individual computers may employ filters called firewalls that use a set of rules to allow or block certain unwanted network traffic (based on IP addresses, ports, or applications that are attempting to send the traffic).

Hardware Firewalls

Hardware firewalls are commonly built into networking equipment (such as routers), and examine each piece of network traffic (known as packets) as they are received and then re-transmitted. The header of each packet contains information about the destination IP address, transport layer protocol used, remote port number, and more. Hardware firewalls can filter packets based on this information and a set of user-defined rules, resulting in certain network packets being allowed and others being dropped without re-transmission.

Although each individual hardware firewall may be configured differently (or have different default settings), many personal network routers are set up by default to allow all outgoing traffic and disable all incoming traffic between a local and external network. All traffic within the local network itself is typically allowed by default, and incoming traffic based on a recent outgoing request is also typically allowed.

Software Firewalls

In addition to the presence of hardware firewalls on network, individual computers may also run firewall software packages to filter network communications and protect against the unwanted influence of remote machines. While software firewalls have a similar objective as hardware firewalls, they use different methods to do this filtering.

Tolako Tolako U-shaped GPIO Expansion Board Breadboard Shield for Raspberry Pi 3 B+
BISS (Tolako)
  • The Raspberry Pi Extension Adapter is an add-on prototyping board which designed for the Raspberry Pi  3 Model B+ ,GPIO Module that can break out all the power...
  • You can plug the 40-pin GPIO cable between the Pi computer and the Pi Port Extender.
  • U Type GPIO Extension Adapter

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