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Unformatted text preview: P POP POP Cable modem POP DSL ISP (for individuals) Small Business Pgh employee DC employee Carnegie Mellon Naming and Communica8ng on the Internet Original Idea Every node on Internet would have unique IP address Everyone would be able to talk directly to everyone No secrecy or authen2ca2on Messages visible to routers and hosts on same LAN Possible to forge source field in packet header Shortcomings There aren't enough IP addresses available Don't want everyone to have access or knowledge of all other hosts Security issues mandate secrecy & authen2ca2on Carnegie Mellon Evolu8on of Internet: Naming Dynamic address assignment Most hosts don't need to have known address Only those func2oning as servers DHCP (Dynamic Host Configura2on Protocol) Local ISP assigns address for temporary use Example: My laptop at CMU (wired connec2on) IP address 188.8.131.52 (corvina.ece.cmu.edu) Assigned sta2cally My laptop at home IP address 192.168.1.5 Only valid within home network Carnegie Mellon Evolu8on of Internet: Firewalls 10.2.2.2 1 4 184.108.40.206 Firewall 2 3 220.127.116.11 Corpora8on X Internet Firewalls Hides organiza2ons nodes from rest of Internet Use local IP addresses within organiza2on For external service, provides proxy service 1. Client request: src=10.2.2.2, dest=18.104.22.168 2. Firewall forwards: src=22.214.171.124, dest=126.96.36.199 3. Server responds: src=188.8.131.52, dest=184.108.40.206 4. Firewall forwards response: src=220.127.116.11, dest=10.2.2.2 Carnegie Mellon Virtual Private...
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- Spring '13