Published on November 15, 2017
1. Proxy Server
2. PROXY SERVER Proxy servers operate as an intermediary between a local network and services available on a larger one, such as the Internet • Proxy share a connection to others • Proxy act as gateway • Proxy act as Cache Server/Firewall 6
3. Purpose of Proxy server Improve Performance Act as Cache server Cache web pages & provide them back without requesting the page again from website server. Bandwidth control Reduces the Bandwidth requirements for an large Organization. Filter Requests Prevent access to some web sites!!! Prevent access to some protocols Prevent access of network on Time Basis. Surfing Anonymously Browsing the WWW without any identification!!!
4. TYPES OF PROXY SERVERS 4 • • • • Caching proxy server Web proxy server Content-filtering web proxy Anonymizing proxy server
5. Main purpose of using proxies Improve Performance Act as Cache server Cache web pages & provide them back without requesting the page again from website server. Bandwidth control Reduces the Bandwidth requirements for an large Organization. Filter Requests Prevent access to some web sites!!! Prevent access to some protocols Prevent access of network on Time Basis. Surfing Anonymously Browsing the WWW without any identification!!!
6. Improving Performance Caching can greatly speed up Internet access. If one or more Internet sites are frequently requested, they are kept in the proxy's cache, so that when a user requests them, they are delivered directly from the proxy's cache instead of from the original Internet site. Caches diminish the need for network bandwidth, typically by 35% or more, by reducing the traffic from browsers to content servers. Bandwidth control – Policy-based Bandwidth Limits – Deny by content type INTERNET 64 Kbps 128 Kbps 512 Kbps 1 Mbps Caching Reduces latency (Sites takes less time to open) Reduces Network Traffic ( Reduces Data uses)
7. MECHANISM OF PROXY SERVER client ISP www.abc.com Block www.xyz.com 10 www.abc.com www.xyz.com Proxy server www.abc.com
8. MECHANISM OF PROXY SERVER 8 Proxy server accepts request from client. It generates response based on two conditions. If the document exits in the local cache, proxy server itself provides the required retrieval to the client.
9. MECHANISM OF PROXY SERVER 9 If there is a cache miss then the request is been forwarded to the original server. The proxy server transfers the replies to the client and also being caches them. The proxy server thus acts both as the client and the server.
10. LAN IP : 172.16.0.1 Proxy Server INTERNET IP : 22.214.171.124 Gw : 126.96.36.199 IP : 172.16.0.2 Gw : 172.16.0.1 Source IP 172.16.0.2 www.yahoo.com Dest IP 188.8.131.52
11. LAN Proxy Server INTERNET IP : 184.108.40.206 Gw : 220.127.116.11 IP : 172.16.0.2 Gw : 172.16.0.1 IP : 172.16.0.1 Source IP 18.104.22.168 www.yahoo.com Dest IP 22.214.171.124 Change Source IP Address Source IP 172.16.0.2 www.yahoo.com Dest IP 126.96.36.199
12. LAN INTERNET IP : 172.16.0.1 Proxy Server IP : 188.8.131.52 Gw : 184.108.40.206 Source IP 220.127.116.11 Dest IP 18.104.22.168 Change Source IP Address & Destination IP Address IP : 172.16.0.2 Gw : 172.16.0.1
13. LAN IP : 172.16.0.1 Proxy Server INTERNET IP : 22.214.171.124 Gw : 126.96.36.199 Source IP 188.8.131.52 Dest IP 184.108.40.206 Change Dest. IP Address Source IP 220.127.116.11 Dest IP 172.16.0.2 IP : 172.16.0.2 Gw : 172.16.0.1
14. LAN IP : 172.16.0.2 Gw : 172.16.0.1 Source IP 18.104.22.168 Dest IP 172.16.0.2 IP : 172.16.0.1 Proxy Server INTERNET IP : 22.214.171.124 Gw : 126.96.36.199
15. HTTP PROXY SERVERS 15 "Middlemen" between clients and servers Proxies which process http requests are known as http proxy servers Proxy Server Looks like a server sending responses Looks like a client making requests
16. KEY FEATURES OF HTTP PROXY SERVERS 16 It may rewrite the client’s requests It Provides Anonymity and Security It is a Caching Proxy server Serves as content filter
17. ADVANTAGES OF HTTP PROXY SERVERS 17 Better Performance Less trafficking Reduces latency Conserves bandwidth Good at logging
19. What DNS do? Convert user friendly names to user-unfriendly strings of long arbitrary number. Simply put convert Domain names to IP addresses and back. http://www.bsnl.co.in. ◦ http:// - protocol that is used ◦ www – browsing service ◦ ‘.’ at the end root domain ◦ co.in - Top level domain (TLD) ◦ bsnl – second level domain
20. hosts file Earlier the name service was done using a local file inside every computer ◦ hosts file ◦ /etc/hosts in *nix ◦ %systemroot%system32driversetchosts in windows It is tedious task to update this file every time a change occurs
21. Domain Name Space Hierarchy DNS is organized in a hierarchical tree structure ◦ Domain Root ◦ Top-Level Domain (TLD) ◦ Second Level Domain ◦ Sub domain ◦ Host or resource
22. FQDN (Fully Qualified Domain Name) jacob.hr.microsoft.com ◦jacob – hostname ◦hr – sub domain ◦microsoft – second level domain ◦.com-TLD
23. DNS Hierachy Root .com/co. google. Mail Drive maps Yahoo Bsnl Rttchyd Rttctvm Alttc DC .gov kerala .mil .edu .int .net Root domain TLD Secondary Subdomain Host dc.alttc.bsnl.co.in(FQDN)
24. Types of DNS servers •Primary •Secondary •Cache only
26. FTP FTP, short for"File Transfer Protocol," can transfer files between any computers that are networked. It is platform independent Works in client server architecture Can be Open or restricted with username and passwords
28. Email Method of electronically sending messages. Store and Forward System. Multiple Copies on one go. Can include acknowledgements. Requires a mail account to operate. Mails are available globally.
29. Email address •Two parts –Separated by @ –eg. username@domain-name –Domain refers to the mail server –Username refers to the unique ID of the user –domain name consists of a dot (".") followed by three or more letters (such as .com and .gov) that indicate the top-level domain (TLD) which indicates the type of organization or the country where the host server is located.
30. Protocols SMTP ◦ Simple Mail Transfer Protocol, Port No. 25 POP3 ◦ Post Office Protocol version 3, Port No. 110 IMAP ◦ Internet Message Access Protocol, Port No. 143
31. POP or IMAP
32. Components of Email • Header – Date, Time, From, To, CC, BCC, Subject • Body
33. HTTP server A web server is a computer system that processes requests via HTTP to distribute information on the World Wide Web. The primary function of a web server is to store, process and deliver web pages to clients. The Pages delivered are most frequently HTML documents, which may include images, style sheets and scripts in addition to text content. Eg of http server : IIS, Apache, nginx..