What is port forwarding?

More self-tutoring about computer networks: the tutor examines the idea of port forwarding.

From a practical point of view, port forwarding is a way to set up a router so that outside inquiries can reach a resource behind it, in the internal network.

Port forwarding relies on a two-part construct:

  1. The application the outside users want dwells on a dedicated device in the internal network;
  2. Said application is reached via a specific port on that specific device.

(See yesterday’s post for an explanation of what a port is.)

Typically, a router will block unsolicited traffic from accessing computers behind it, which is its firewall function.

Let’s imagine the application you want to enable outside users to access is reached via port x0y0 on local device D0. The port forward that will enable such access:

Router, when a request for port x0y0 arrives, send it along to D0, port x0y0.

Now, outside clients can reach that inner device D0, through the firewall and past the router, by virtue of their request for port x0y0. The setup is called port forwarding.

Source:

CCTV Camera Pros

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

What is a port in computer networking?

Self-tutoring about computer networks: the tutor offers a definition of the common networking term port.

A port can be physical or logical. A physical port is a plug-in socket at which to attach a device to the computer, such as a printer. USB ports comprise an example.

A logical port, such as port 80, designates the program a request desires to connect through. Port 80 means http activity. The logical ports on a computer are 0 to 65535.

Source:

searchnetworking.techtarget.com

SimplifiedTechExplanations

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Computer networks: what is a switch?

More technology self-tutoring: the tutor explains his understanding of switch, a term he’s found tricky to define.

For background, my post from April 2, as well as my post from yesterday, connect with today’s topic.

Switches can be used in a variety of ways, so a simple conception only explains one application. However, I find this idea helpful:

Imagine a self-contained local network of computers physically connected. A given member can send a message to a specific other, or to all others at once. Then, the simplest central connection among these computers is a switch.

A switch is different from a hub (once again, my post from yesterday) in that the switch can forward a message to a specific intended recipient, whereas the hub just forwards it to everyone.

Source:

askleo.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Computer science, networks: what is a hub?

More technology self-tutoring: the tutor investigates the term hub in networking.

hub (in computer network):
a central device to which computers can be connected to form a local network. Data the hub receives from one computer will be forwarded to all the others to which it’s connected.

Source:

askleo.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Computer science, networks: what is a Peer-to-peer (P2P) network?

More self-tutoring about computer networks: the tutor shares the definition of peer-to-peer network.

Peer-to-Peer (P2P) network:

A network in which any computer is directly connected to any other, rather than through a server. The premise of P2P seems to be that the members are physically connected by wire.

The arrangement could be two computers connected, for example, by USB. It could also be a larger set of computers all connected along one main rail.

Source:

www.computerworld.com

www.w3schools.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Networking, OSI model: Layer 2 vs Layer 3

Reading about networks leads to self-tutoring: the tutor mentions some ideas about Layer 2 vs Layer 3 in computer networks.

As I understand, Layer 2, aka the link layer, is associated with data transmission in the context of frames. A simplified point of view about it imagines physically connected devices communicating. In broadcast mode, every member forwards all its output to every other member. However, output can be sent to only a specific member. Connected members have no nodes between them; each member is directly connected to any other. The Layer 2 network is self-contained.

Layer 3 uses packets, rather than frames, to organize data. It’s populated by routers. In Layer 3, a given data packet has one intended recipient; the others on the network will not see it. The router conducts each packet to its appropriate destination. Layer 3 is needed when there are intervening nodes between ones that want to communicate – hence, the need for routing the packets of information to their specific destinations. Layer 3 is the context for communication to happen between different networks.

Source:

www.wideband.net.au

stackoverflow.com

www.networkworld.com

networkengineering.stackexchange.com

askleo.com

www.computerworld.com

documentation.meraki.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Computer science: networking: what is a virtual connection?

In tutoring, definitions are always important. The tutor shares the definition of virtual connection.

virtual connection:

A virtual connection is a software-initiated connection between two nodes in a network. (See yesterday’s post for the definition of a node.)

When you visit a site on the internet from your browser, you establish a virtual connection with that server.

Source:

www.pcmag.com

www.w3schools.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Computer science, networks: what is a node?

Understanding computer networking leads to self-tutoring: the tutor defines node in computer networks.

node (noun):

an endpoint, or else a directing or processing device between endpoints. The endpoint could be a PC, printer, scanner, server, etc: at an endpoint, content either enters the network or is received there.

The directing device could be a router.

There are different points of view about nodes depending on the type of network, etc. However, one point of view imagines a node as a point where information enters, is received, or is processed in some way to make it available to its end user. A router, for instance, directs information to its various specific requesters.

Source:

audiopedia

www.lifewire.com

www.lifewire.com

whatismyipaddress.com/router

www.howtogeek.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.