1. PACKET ANALYSIS WITH WIRESHARK DHCP, DNS, HTTP Chanhyun park

2. DHCP Dynamic Host Configuration Protocol Standardized network protocol for dynamically distributing network configuration parameters such as IP address Computers get IP address and networking parameters from a DHCP server Subnet mask, router, domain name server Packet format is well described in WIKI http://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Pro tocol http://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Pro tocol

3. DHCP – sequence DHCP Discover DHCP Offer DHCP Request DHCP Ack Search DHCP server DHCP server replies with available IP address Server allocate IP address for client with options and update IP address database Client select one DHCP server, request IP address and networking parameters Client start with DHCP Request when there is already DHCP IP

4. DHCP – sequence DHCP Discover DHCP Offer DHCP Request DHCP Ack Client start with DHCP Request when there is already DHCP IP

5. DNS Domain Name System

6. DNS Domain Name System Google.com -> 173.194.127.100

7. DNS Ethernet IP UDP

8. DNS message format 1 byte2 byte3 byte4 byte IdentifierFlag Num of QuestionsNum of Answers Num of AuthoritiesNum of Additional Records Questions Answers Authorities Additional Records

9. DNS message format 1 byte2 byte3 byte4 byte Identifier: 0x804bFlag: 0x0100 Num of Questions: 1Num of Answers: 0 Num of Authorities: 0Num of Additional Records: 0 Questions: www.facebook.com, type A, class INwww.facebook.com Answers Authorities Additional Records

10. HTTP HyperText Transfer Protocol Application protocol for distributed, collaborative, hypermedia information systems. 1996 – version 1.0 1999 – version 1.1 http://www.tcpipguide.com/free/t_HTTPRequestMessageFormat.htm

11. HTTP Request Line – method, URI HEAD, GET, POST, PUT, DELETE, TRACE, OPTIONS, CONNECT Header Fields General, Request / Response, Entity Name, :, values Message Body http://www.tcpipguide.com/free/t_HTTPRequestMessageFormat.htm

12. HTTP – Wireshark results daum.net

13. Question?