INTERNET SERVICES, PROTOCOLS, APPLICATIONS, PACKETS AND FRAMES

CRAMAROSSA GIUSEPPEAPRIL 2015

TOPICS• INTERNET SERVICES• PROTOCOLS• PORTS• PACKETS• FRAMES• ISO/OSI MODEL

COMMUNICATION IN INTERNET• INTERNET SERVICES OR APPLICATION• Mailing lists• E-commerce• File Transfer• WWW• Instant messagging

• USE OF A WIDE VARIETY OF PROTOCOLS

PROTOCOLS• A SET OF PREDEFINED RULES AND SYMBOLS• ADVANTAGES

• Two or more devices from different vendors can communicate each other

• EXAMPLES OF APPLICATION PROTOCOLS• HTTP• FTP• POP3• SMTP• DNS

• SOME OF THEM HAVE A SECURE VERSION• THEY HAVE CLIENT AND SERVER APPLICATIONS• THEY USE ONE OR MORE PORTS

PORTS• NUMBER BETWEEN 0 AND 65535 • IDENTYFIES THE REQUESTED SERIVICE• THERE ARE 3 CATEGORY OF PORTS

• Well-kwown ports 0 - 1023• Registered ports• Dynamic Ports

• EXAMPLES• HTTP: 80• FTP: 20, 21• POP3: 110• SMTP: 25• DNS: 53

SERVER APPLICATIONS• PROVIDES A RESPONSE TO A CLIENT REQUEST• IN A HOST THERE COULD BE ONE OR MORE SERVER

APPLICATIONS• EXAMPLES• HTTP: Apache• FTP: Filezilla • POP3: Mercury Mail• SMTP: Mercury Mail

• THEY USE STATIC PORTS

CLIENT APPLICATIONS• REQUEST A SERVICE TO A SERVER APPLICATION• IN A HOST THERE COULD BE ONE OR MORE CLIENT

APPLICATIONS• EXAMPLES• HTTP: Web Browsers• FTP: Filezilla • POP3: Outlook Express• SMTP: Outlook Express

• THEY USE DYNAMIC PORTS

TRANSPORT PROTOCOLS• APPLICATIONS USE TANSPORT PROTOCOLS IN ORDER TO SEND AND

RECEIVE PACKETS • SOME OF THEM ARE

• TCP• Connection oriented• Reliable• Three-way handshake

• UDP• Connectionless• Unrealible

• HANDLE TWO CONNECTION MODE• Unicast• Multicast

PACKETS AND FRAMES• LAYER 2 OF THE ISO-OSI MODEL HANDLES FRAME• THESE FRAMES ARE FORWARDED BY A SWITCH• BY LAYER 3 OF THE ISO-OSI MODEL, FRAMES BECOMES PACKET• THESE FRAMES ARE FORWARDED BY A ROUTER USING ROUTING

PROTOCOLS• DEPEND ON THE TRANSPORT PROTOCOL USED

OSI MODEL AND TCP/IP • DEVELOPED BY INTERNATIONAL STANDARD ORGANIZATION• OSI MODEL• Is a theorical model• Modular• It is made up of 7 layers

• Each layer can communicate with its upper and lower layer• Each module is independent

• TCP/IP• It is the model used in networking• Modular• Four layers