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Proxy Server


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Proxy Server

  2. 2. TEAM MEMBERS <ul><li>Ekta </li></ul><ul><li>Supriya </li></ul><ul><li>Malini </li></ul><ul><li>Manasa </li></ul><ul><li>Gowri </li></ul>
  3. 3. AGENDA <ul><li>Introduction </li></ul><ul><li>What is a proxy server? </li></ul><ul><li>Purpose of proxy server </li></ul><ul><li>Types of proxy server </li></ul><ul><li>Mechanism of proxy server </li></ul><ul><li>Understanding briefly about http and ftp protocol </li></ul><ul><li>Understanding http and ftp proxy servers </li></ul>
  4. 4. PROTOCOL <ul><li>A protocol is set of rules for data representation, authentication, and error detection. </li></ul>
  5. 5. INTRODUCTION TO HTTP <ul><li>Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. </li></ul>
  6. 6. PROXY SERVER <ul><li>A proxy server is a server that acts as an intermediary for requests from clients seeking resources from other servers. </li></ul>
  7. 7. PURPOSE OF PROXY SERVER <ul><li>Proxy servers have two main purposes: </li></ul><ul><li>To keep machines behind it anonymous (mainly for security) </li></ul><ul><li>To speed up access to a resource (via caching). It is commonly used to cache web pages from a web server. </li></ul>
  9. 9. TYPES OF PROXY SERVERS <ul><ul><li>Caching proxy server </li></ul></ul><ul><ul><li>Web proxy server </li></ul></ul><ul><ul><li>Content-filtering web proxy </li></ul></ul><ul><ul><li>Anonymizing proxy server </li></ul></ul>
  10. 10. MECHANISM OF PROXY SERVER Proxy server client ISP Block
  11. 11. MECHANISM OF PROXY SERVER <ul><li>Proxy server accepts request from client. </li></ul><ul><li>It generates response based on two conditions. </li></ul><ul><li>If the document exits in the local cache, proxy server itself provides the required retrieval to the client. </li></ul>
  12. 12. MECHANISM OF PROXY SERVER <ul><li>If there is a cache miss then the request is been forwarded to the original server. </li></ul><ul><li>The proxy server transfers the replies to the client and also being caches them. </li></ul><ul><li>The proxy server thus acts both as the client and the server. </li></ul>
  13. 13. HYPER TEXT TRANSFER PROTOCOL(HTTP) <ul><li>Used to access data in WWW. </li></ul><ul><li>to transfer data in the form of hypertext, plaintext, audio, video. </li></ul><ul><li>It functions like a combination of FTP and SMTP. </li></ul>
  14. 14. HYPER TEXT TRANSFER PROTOCOL(HTTP) <ul><li>It is similar to FTP because it transfers files and uses the services of TCP. </li></ul><ul><li>It is simpler than FTP as it uses only one TCP connection on a well known port 80. </li></ul>
  15. 15. HTTP (CONT…) <ul><li>It is similar to SMTP since data are transferred from client and the server. </li></ul><ul><li>Http differs from SMTP in the way messages are sent. </li></ul><ul><li>Http are not destined to be read by humans </li></ul><ul><li>They are read and interpreted by the http server and http client. </li></ul><ul><li>Client sends a request which look like mail to the server. </li></ul><ul><li>The server sends the response which looks like a mail reply to the client. </li></ul><ul><li>Http itself is a stateless protocol. </li></ul>
  16. 16. HTTP (CONT..) <ul><li>Client sends a request which look like mail to the server. </li></ul><ul><li>The server sends the response which looks like a mail reply to the client. </li></ul><ul><li>Http itself is a stateless protocol. </li></ul>
  17. 17. FILE TRANSFER PROTOCOL (FTP) <ul><li>It is a standard mechanism provided by the internet for copying a file from one host to another. </li></ul><ul><li>There are many difficulties in file transfer. </li></ul><ul><li>It establishes two TCP connections between the client and the server. </li></ul>
  18. 18. FILE TRANSFER PROTOCOL (FTP) <ul><li>One connection for data transfer other for control information(commands and response). </li></ul><ul><li>It is more efficient and the control connection is simpler whereas the data connection is complex. </li></ul>
  19. 19. HTTP PROXY SERVERS <ul><li>&quot;Middlemen&quot; between clients and servers </li></ul><ul><li>Proxies which process http and (not always) </li></ul><ul><li>ftp requests are known as http proxy servers </li></ul>Proxy Server Looks like a server sending responses Looks like a client making requests
  20. 20. KEY FEATURES OF HTTP PROXY SERVERS <ul><li>It may rewrite the client’s requests </li></ul><ul><li>It Provides Anonymity and Security </li></ul><ul><li>It is a Caching Proxy server </li></ul><ul><li>Serves as content filter </li></ul><ul><li>Multithreading </li></ul>
  21. 21. ANONYMITY OF A HTTP PROXY <ul><li>HTTP proxy servers have several anonymity levels </li></ul><ul><li>Based on Anonymity degree, they are classified as: </li></ul><ul><li>Transparent </li></ul><ul><li>Anonymous </li></ul><ul><li>Distorting </li></ul><ul><li>Highly Anonymous </li></ul>
  23. 23. FUNCTIONS OF HTTP PROXY SERVER <ul><li>Caching </li></ul><ul><li>Reduces Latency </li></ul><ul><li>Reduces Traffic on the web </li></ul><ul><li>Bandwidth Conservation </li></ul><ul><li>Increases accessibility </li></ul><ul><li>firewalling and filtering </li></ul><ul><li>connection sharing </li></ul>
  24. 24. ADVANTAGES OF HTTP PROXY SERVERS <ul><li>Better Performance </li></ul><ul><li>Less trafficking </li></ul><ul><li>Reduces latency </li></ul><ul><li>Conserves bandwidth </li></ul><ul><li>Good at logging </li></ul>
  25. 25. DISADVANTAGES OF HTTP PROXY SERVERS <ul><li>Proxy services lag behind nonproxied services </li></ul><ul><li>Proxy services may require different servers for each service </li></ul><ul><li>Proxy services usually require modifications to clients, procedures, or both </li></ul><ul><li>Proxy services don't protect you from all protocol weaknesses </li></ul><ul><li>Proxy services are not workable for some services </li></ul>
  26. 26. FTP PROXY SERVERS <ul><li>An ftp proxy server support file sharing on networks using the file transfer protocol (ftp) </li></ul><ul><li>Concurrency control </li></ul><ul><li>Master mechanism </li></ul><ul><ul><li>Opens port </li></ul></ul><ul><ul><li>Waits for client </li></ul></ul><ul><ul><li>Choose port </li></ul></ul><ul><ul><li>Starts slave </li></ul></ul><ul><ul><li>Continue </li></ul></ul>
  27. 27. FTP PROXY SERVER(CONT..) <ul><li>Slave Mechanism </li></ul><ul><li>Keep control processes and the control connection alive as long as the ftp session is alive </li></ul><ul><li>We can use ftp proxy server in two modes </li></ul><ul><ul><li>Active </li></ul></ul><ul><ul><li>Passive </li></ul></ul>