WHAT IS TROJANS ?

TROJANS:-A Trojan horse is full of trickery as its name reflects. The Trojan horse, at first glance will appear to be a useful software but will actually damage the computer once it is installed. Users on the receiving end of a Trojan horse are usually tricked into opening them because they appear to be receiving useful software r files from a genuine source. When a Trojan is activated on a computer, the results can vary. Some Trojans are designed to be more irritating than malicious (like changing your desktop, adding silly active desktop icons ) or they can cause serious damage by deleting files and destroying information on a system. Trojans are also known to create a backdoor on a computer that gives an easy access to malicious users, thus allowing your confidential or personal information to be compromised. Unlike viruses and worms, Trojans do not reproduce by infecting other files nor do they self replicate.
Trojans come in two parts, a Client part and a server part. when the victim unknowingly runs the server on its machine.the attacker then uses the client to connect to the server and starts using the Trojan.
TCP/IP protocol is the usual protocol type used for communications, but some functions of the Trojans also use the UDP  (User Datagram Protocol).