Remote Connection to a machine is accessing a computer(host/server) from your machine(client as if it is in front of you.The host might be located anywhere,yet it can accessed completely without physically touching it.
Remotely connecting to a machine is not a difficult task, and is found useful by many.It finds uses in distant troubleshooting i.e. companies like Dell,HCL are consistently using this technique to solve minor problems in computers. People
use remote connection to connect to their office PC's from their homes. In short it is a very important technique that one must know.
Remote connection can be established using graphical utilities or command line.
The number of utilities is enormous.For every OS, one can find a great number of utilities following various protocols.One must always remember that to establish a connection one must always use a software following the same protocol(set of rules) on both sides.
What exactly happens when using graphical utilities-The copy of the image received from host's display screen is displayed on the screen of the client.This copy is updated on a timed interval, or whenever the screen changes.The keyboard and mouse of the client are transmitted to the host and implemented. The host behaves as if the actions were performed directly at that computer.
In many cases the local display and input devices can be disabled to prevent interference,else the user at the host side may not let the client control the host.
Now,these softwares follow various protocols,the main ones being-
1)Remote Desktop Protocol (RDP) for Windows-
It is a proprietary protocol developed by Microsoft and clients exist for most versions of Microsoft Windows Linux, Mac OS X and other OS.By default the server listens on TCP port 3389
2)Remote Frame Buffer Protocol (RFB) a frame buffer level protocol-
It works at the frame buffer level and so is applicable to all windowing systems and applications, Windows and Mac.RFB is the protocol used in Virtual Network Computing (VNC).By default use TCP port 5900 or 5800 for browser access. A server can
3)Apple Remote Desktop Protocol (ARD) for Mac OS X machines-
It basically uses the RFB protocol only,but is known to cater to a utility that is user-friendly.
The important things that one must remember is that RDP/RFB (on port 3389 and 5900 respectively) should be allowed.The router needs to be configured to forward port 3389/5900 on the computer in consideration.The computer being connected to must not hibernate or stand-by or sleep. It must be powered on during the session.And finally the computers must be connected to the internet.
The only small challenge that one may face is the IP address of the host,when the host is not a part of the local network.Generally computers have Dynamic IP addresses that is it keeps changing every time a computer is switched off.
Also on the internet what is identified is only the router and within the local network it is the router which assigns IP addresses that keep changing.So either one can buy a static IP for a PC or one may leave his computer on all the time,which is not practical. Therefore,there are softwares like Teamviewer that remove the need of the IP address on the user front.
To know more about it one may use the following URL:-
In command line access one may use ssh(secure shell) or telnet in OS's providing a terminal. If one wants to establish command line connection in windows,then one needs softwares like Putty,that provide a terminal for Windows.
In computers nothing is difficult and the same applies to remote connection to a machine.