Protocolo tcp/ip

TCP-IP Protocol
Facilitador: Diego Avila P.

TCP-IP Protocol

Aplication Layer
HTTP (WWW)
We will examine HTTP in detail.

DHCP (IP address resolution)

FTP (file transfer)

DNS (domain name resolution)

SMTP (email)

SMB (file sharing)

Telnet (remote login)

P2P (file sharing)

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HTTP (HyperText Transfer Protocol)
HTTP HTTP Server HTTP Client HTTP

Implementedin: Client program Server program Web page (also called a html document) Web page consists of objects HTML file JPEG image JAVA applet Audio file

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HTTP Request Message

Some data omitted for brevity GET /~rgraziani/ HTTP/1.1 Accept-Language: en-us User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506; InfoPath.1)Host: www.cabrillo.edu Connection: Keep-Alive

HTTP Server HTTP Client

Request Message Request line Header lines ASCII Text
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HTTP Response Message
HTTP/1.1 200 OK Date: Fri, 22 Feb 2008 16:34:18 GMT Server: Apache/2.0.52 (Red Hat) Last-Modified: Thu, 15 Nov 2007 19:33:12 GMT Content-Length: 15137 Connection: close Content-Type: text/html Some data omitted for brevity



HTTP ServerHTTP Client
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HTTP Request and Response Messages
GET /~rgraziani/ HTTP/1.1 Accept-Language: en-us User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506; InfoPath.1) Host: www.cabrillo.edu Connection: Keep-Alive

HTTP

HTTP Server

HTTP HTTP Client

HTTP/1.1 200 OK Date: Fri, 22 Feb 2008 16:34:18 GMT Server:Apache/2.0.52 (Red Hat) Last-Modified: Thu, 15 Nov 2007 19:33:12 GMT Content-Length: 15137 Connection: close Content-Type: text/html



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HTTPS

HTTPS (Hypertext Transfer Protocol over Secure Socket Layer) is a URL scheme used to indicate a secure HTTP connection. HTTPS is not a separate protocol combination of a normal HTTP interaction over an encrypted: Secure Sockets Layer (SSL) orTransport Layer Security (TLS) connection

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FTP (File Transfer Protocol)
FTP Client FTP Server

FTP was developed to allow for file transfers between a client and a server. Used to push and pull files from a server running the FTP daemon (FTPd). RFC 959

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FTP (File Transfer Protocol)
TCP control connection port 21
Username and password Change directory on Server

TCP dataconnection port 20
Copy file from client to server – Connection Closed

TCP data connection port 20
Copy file from server to client – Connection Closed

TCP control connection port 21
Quit FTP Application – Connection Closed

Client initiates a TCP control connection with FTP server using port 21. This connection remains open until the user quits the FTP application. TCP port 21 connectionincludes: Username and password is sent over TCP port 21. Remote directory changes This state information significantly reduces total number of sessions on server. For each file transferred, TCP opens and closes a TCP data connection on port 20.

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SMTP – Simple Mail Transfer Protocol
User agent SMTP Mail server SMTP POP3 IMAP Mail server User agent

Internet mail involves: User agentsAllows users to read, reply, compose, forward, save, etc., mail messages GUI user agents: Outlook, Eudora, Messenger Text user agents: mail, pine, elm Mail servers Stores user mail boxes, communicates with local user agents and other mail servers. SMTP Principle application layer protocol for Internet mail Sent over TCP 11 Mail access protocols: POP3, IMAP4, HTTP

Telnet

Telnet

Telnet ServerAllows a user to remotely access another device (host, router, switch). Connection called a Virtual Terminal (VTY) session. Telnet clients: Putty Teraterm Hyperterm
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Telnet

Supports user authentication, Does not encrypt data. Secure Shell (SSH) protocol offers an alternate and secure method for server access. Stronger authentication Encrypts data

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DHCP – Dynamic Host...