1. IT 210: Web-based IT Fall 2012 IP Address Details & HTTP Protocol

2. IP Address Details

3. Refresher…  What function do IP Addresses serve?

4. IP Addresses  Composed of 2 parts: network ID (prefix assigned by ISPs) and host ID (suffix assigned by local sysadmin)  IPv4 addresses consist of 4 octets  How much of the IP address is used as a network ID? 216.24.63.132

5. Assigning IP Addresses

6. Classful IP Address Assignment

7. IP address classes (32 bits = v4) ClassLeftmos t bits Start address Finish address Net bitsHost bits A0xxx0.0.0.0127.255.255.2 55 724 (16M) B10xx128.0.0.0191.255.255.2 55 1416 (65K) C110x192.0.0.0223.255.255.2 55 218 (256) D1110224.0.0.0239.255.255.2 55 multicast E1111240.0.0.0255.255.255.2 55 experimental

8. Many exceptions  127.0.0.0 -127.255.255.255 = loopback 127.0.0.1 = “home” or localhost  Private addresses (see table) ClassPrivate start addressPrivate end address A10.0.0.010.255.255.255 B172.16.0.0172.31.255.255 C192.168.0.0192.168.255.255

9. Script Kiddies

10. CIDR (Classless Inter-Domain Routing)  The “prefix” (ironically shown after the IP address) indicates how many bits in the Network ID. E.g., 192.168.0.0/16 CIDR & # of Hosts /13 524,288 /14 262,144 /15 131,072 /16 65,536 /17 32,768 /18 16,384 /19 8,192 /20 4,096 /21 2,048 /22 1,024 /23 512 /24 256 /25 128 /26 64 /27 32

11. Dynamic vs Static IP Addresses  Static vs Dynamic

12. IP4 vs IP6  In Jan 2011 we ran out of IPv4 addresses.  IP4: 32-bit address 4.2 billion addresses available (2 32 ) 10.8.240.2  IP6: 128-bit address 3.4 x 10 38 addresses available (2 128 ) 2001:0f68:0000:0000:0000:0000:1986:69af which condenses to 2001:f68::1986:69af

13. Aside: What is an RFC?  RFC “Request for Comment” Modern RFCs are NOT requesting comments (Draft docs are used for that) Standards, informational, and other stuff Published by IETF  IETF = Internet Engineering Task Force

14. References  RFC 1518 - An Architecture for IP Address Allocation with CIDR RFC 1518  RFC 1519 - Classless Inter-Domain Routing (CIDR): an Address Assignment and Aggregation Strategy RFC 1519  RFC 2373 - IP Version 6 Addressing Architecture RFC 2373

15. Questions…  True or False: The classless inter-domain routing (CIDR) system helps assure that fewer IP addresses are “wasted”.  True or False: When I switch networks my IP address will also need to change.  How many unique IP addresses are there in IP4 and IP6?

16. Open up command-line…  Type in ipconfig  Now try ipconfig /all  Compare the IP address to what you find here: http://www.whatismyip.comhttp://www.whatismyip.com  Try this again at home. Will it be different?

17. HTTP

18. See online tutorial  http://www3.ntu.edu.sg/home/ehchua/pr ogramming/webprogramming/HTTP_Basic s.html http://www3.ntu.edu.sg/home/ehchua/pr ogramming/webprogramming/HTTP_Basic s.html