Computer Networks and how does the Internet work?

Transcript

1. Computer Networks and how does the Internet work?
2. Hi, I am Sumedh. - Backend at Polygon Students (Remote) - Former intern at Devfolio, HackerRank - Google Summer of Code 2017 fellow - Managing WebDev Labs, SVNIT. - Struggling to pass my 8th semester in college.
3. Why Computer Networks?
4. History - Large computers in old times - Computer networks were used only in an organization. - They shared physical resources. - LAN
5. One second on the Internet - 34, 875 GB of Traffic - 12 Uber Rides - 7, 203 Tweets - 721 Instagram photo uploads - 305 Reddit votes - 4, 86, 111 WhatsApp messages sent - 24, 88, 887 Emails - And much more. And much more.
6. What will we discuss today? - Network packets - Transmission protocols - Routers, Gateways, DHCP - DNS - SSL/TLS - Some words used by cool kids.
7. - All computers connected to each other - packet reaches every computer on the network. Duh? - MAC Address assigned to each computer helps in that. Ethernet
8. - Media access control(MAC) - receive only if meant for them ✅ ✅ ✅ ✅ ✅
9. Collisions
10. Collisions reduction
11. Routing (Early days) (Circuit switching)
12. Routing (Early days) Message switching - use different routes - like a postal system - hop count - downsides - large message size
13. - chopping of data into small packets. - passing to flexible routes. - whole internet runs on it today - decentralized Packet Switching - A routing approach
14. Internet Protocol - standard created in 1970s. - each computer gets an IP address. - IPv4, IPv6 - routing protocol - congestion control - packets out of order 172.21.1.10 An IP address A 32 bit number separated by dots per 8 bit.
15. Out of order arrival
16. TCP/IP, UDP IP header Data payload - TCP/IP (run on top of IP) - IP protocol takes the packet to the right computer. - TCP, UDP takes it to the correct program. - TCP can handle packet drop, retransmission, throttling. - people still using UDP at some places? TCP header UDP header
17. - protocol - IP addresses - router - NAT - dhcp - gateway - ISP - DNS - SSL/TLS Terms
18. Packet IP header Data payload - IP takes the packet to the right computer. - UDP takes it to the correct program. (computer assigns port number to each process)
19. Router - routing table - gateways - dhcp - network address translation
20. NAT
21. NAT To your computer the connection looks like: 192.168.1.100:37641 → 72.14.204.147:80 But to the web server, the connection looks like: 104.244.42.129:59273 → 72.14.204.147:80 Private IP Private port Public IP Public port Remote IP Remote port 192.168.1.100 37641 104.244.42.129 59273 72.14.204.147 80
22. Internet service provider
23. Domain Name System - resolver - caching - tree storage in TLD domain server
24. - secure socket layer - secure/insecure browser connections? SSL/TLS
25. SSL/TLS
26. What all is needed to access any website?
27. Let’s revise
28. Thank you! Twitter: @lunatic_monk Telegram: @lunaticmonk Medium: @lunaticmonk