1 00:00:00,000 --> 00:00:00,500 2 00:00:00,500 --> 00:00:03,150 VIDEO: P And he's got your address. 3 00:00:03,150 --> 00:00:05,880 4 00:00:05,880 --> 00:00:10,090 Warriors of the net. 5 00:00:10,090 --> 00:00:12,660 Right so coming soon is how the internet works. 6 00:00:12,660 --> 00:00:13,160 And it's not 7 00:00:13,160 --> 00:00:16,399 DAVID MALAN: Coming soon 15 years ago. 8 00:00:16,399 --> 00:00:18,190 I've always had misgivings with that video. 9 00:00:18,190 --> 00:00:18,820 I love it. 10 00:00:18,820 --> 00:00:21,010 And the team at Ericsson, I think at the time, 11 00:00:21,010 --> 00:00:23,350 was really pushing the envelope with some graphics work. 12 00:00:23,350 --> 00:00:25,930 But it takes some liberties with accuracy. 13 00:00:25,930 --> 00:00:28,750 Uses some terms that even I haven't heard. 14 00:00:28,750 --> 00:00:30,761 But it does actually paint a nice visual picture 15 00:00:30,761 --> 00:00:33,260 of some of what goes on underneath the hood in the internet. 16 00:00:33,260 --> 00:00:34,010 DOUG LLOYD: Right. 17 00:00:34,010 --> 00:00:36,440 It can be a pretty abstract concept. 18 00:00:36,440 --> 00:00:39,760 So even to have some idea, even if it's an imperfect 19 00:00:39,760 --> 00:00:43,044 one, of how the internet works is good. 20 00:00:43,044 --> 00:00:45,460 DAVID MALAN: And we actually spend a decent amount of time 21 00:00:45,460 --> 00:00:48,390 in this lecture on how the internet works and how home networking works. 22 00:00:48,390 --> 00:00:51,306 And in fact, that's what the picture was that was on the screen there. 23 00:00:51,306 --> 00:00:55,570 I think that was a sample page from a routers documentation online. 24 00:00:55,570 --> 00:01:01,000 And it's a nice opportunity, I think, to remind students of the very topology 25 00:01:01,000 --> 00:01:01,960 that they have at home. 26 00:01:01,960 --> 00:01:06,850 Probably some Wi-Fi reception in their home, apartment, in their dorm room, 27 00:01:06,850 --> 00:01:08,770 or office. 28 00:01:08,770 --> 00:01:13,100 And to start to peel back those layers and explain how it works. 29 00:01:13,100 --> 00:01:18,010 DOUG LLOYD: Have you ever considered a pset that touches on is? 30 00:01:18,010 --> 00:01:22,150 So last year, we did server which vaguely touches on HTTP. 31 00:01:22,150 --> 00:01:25,450 Which is what we're starting to talk about here. 32 00:01:25,450 --> 00:01:28,380 But this year, we didn't actually have a problem set during this week. 33 00:01:28,380 --> 00:01:32,651 This was during the week of our first midterm. 34 00:01:32,651 --> 00:01:34,150 DAVID MALAN: We moved things around. 35 00:01:34,150 --> 00:01:37,630 I mean, for me, I like the societal relevance here. 36 00:01:37,630 --> 00:01:41,230 I think this ties in very well to our new CS50 AP initiative. 37 00:01:41,230 --> 00:01:44,960 Where it shows the intersection of technology and society. 38 00:01:44,960 --> 00:01:48,010 But for me, the functional role of this material beyond just 39 00:01:48,010 --> 00:01:54,220 being enlightening, and I think good for everyone to know in the real world. 40 00:01:54,220 --> 00:01:59,560 Is that it really sets the stage for a look at web programming later on. 41 00:01:59,560 --> 00:02:05,200 And it allows us to broaden the canvas of opportunities for students 42 00:02:05,200 --> 00:02:06,720 to program and solve problems on. 43 00:02:06,720 --> 00:02:09,590 Now to programming for the web or for mobile devices and the like. 44 00:02:09,590 --> 00:02:13,569 And I think understanding those basic implementation details is compelling. 45 00:02:13,569 --> 00:02:15,610 Especially when we start talking about protocols. 46 00:02:15,610 --> 00:02:19,292 Like HTTP and explaining how HTTP supports cookies and with cookies can 47 00:02:19,292 --> 00:02:20,000 you get sessions. 48 00:02:20,000 --> 00:02:24,100 And so, we can continue our discussion of abstraction and layering more 49 00:02:24,100 --> 00:02:28,660 and more sophisticated functionality on top of lower level implementation 50 00:02:28,660 --> 00:02:29,380 details. 51 00:02:29,380 --> 00:02:32,660 DOUG LLOYD: This really sets the stage for what's to come in the future weeks. 52 00:02:32,660 --> 00:02:36,772 DAVID MALAN: Indeed And I think you never have a more attentive audience 53 00:02:36,772 --> 00:02:38,980 or student body than when you're talking about things 54 00:02:38,980 --> 00:02:40,750 that are so relevant to them. 55 00:02:40,750 --> 00:02:43,930 And understanding how messages are being transmitted 56 00:02:43,930 --> 00:02:47,230 from their phone to another phone, or through the airwaves in a room 57 00:02:47,230 --> 00:02:47,850 and so forth. 58 00:02:47,850 --> 00:02:51,910 And what kind of threats you expose yourself to by using insecure Wi-Fi, 59 00:02:51,910 --> 00:02:53,745 or by using a weak password. 60 00:02:53,745 --> 00:02:55,870 In fact, we'll continue this discussion of security 61 00:02:55,870 --> 00:02:59,740 later on when we look at SQL, databases, and how you can accidentally 62 00:02:59,740 --> 00:03:00,900 render yourself vulnerable. 63 00:03:00,900 --> 00:03:03,370 Early in the semester we talked about buffer overflow exploits 64 00:03:03,370 --> 00:03:05,119 in the context of C and memory management. 65 00:03:05,119 --> 00:03:07,120 So there's a lot of opportunities, I think, 66 00:03:07,120 --> 00:03:10,510 to discuss throughout the arc of a CS course. 67 00:03:10,510 --> 00:03:12,667 Some real world security privacy issues as well. 68 00:03:12,667 --> 00:03:15,250 And that just motivates an understanding of this all the more. 69 00:03:15,250 --> 00:03:19,870 So that even if you are threatened every day in some form technologically, 70 00:03:19,870 --> 00:03:23,800 at least you can weigh the risks against the benefits 71 00:03:23,800 --> 00:03:26,770 of using these various technologies and decide for yourself. 72 00:03:26,770 --> 00:03:31,270 As opposed to being ignorant completely to what attacks you might suffer. 73 00:03:31,270 --> 00:03:33,610 DOUG LLOYD: No, that's a great point. 74 00:03:33,610 --> 00:03:34,133