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From the previous lectures, 2

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we learned the basics of how networks work. 3

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We learned that devices on the same network communicate 4

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with each other using packets. 5

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So regardless of what you do on the network, 6

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whether you're watching a video, 7

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whether you're logging into a website, 8

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sending chat messages, sending emails, 9

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regardless of what you're doing, 10

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all the data is sent as packets. 11

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Now, in the network, 12

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devices ensure that these packets go 13

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in the right direction using the MAC address 14

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so each packet has a source MAC and a destination MAC 15

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and it flows from the source to the destination. 16

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So in this example, we have the client, 17

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it has this MAC, 18

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we have the access point which has this MAC 19

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and as an example, if this client wanted 20

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to send a packet to the router, 21

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it will set the destination MAC 22

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to the router's MAC address. 23

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Therefore, by default, 24

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each device only receives data that has the destination MAC 25

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as its own MAC address. 26

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But if you remember, I said in wireless networks, 27

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if you're within range, 28

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then you'll be able to capture all of this communication 29

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because these packets are literally sent in the air. 30

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So we can just capture them 31

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even if they do not have our MAC address 32

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as the destination MAC. 33

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To do this, we need to change the mode 34

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of operation of our wireless interface 35

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so that it operates in monitor mode. 36

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So let me show you what I mean. 37

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If I go to my computer here, 38

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and run iwconfig this time, 39

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so we've seen ifconfig which lists all the interfaces, 40

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we can use iwconfig to see the wireless interfaces only. 41

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And you can see, we have lan0 right here 42

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which is my external wireless adapter. 43

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And you can see the mode of this adapter 44

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is set to Managed. 45

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What this means is basically this is the default mode 46

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of all wireless devices 47

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and what it means is this device 48

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will only capture packets 49

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that has the destination MAC 50

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as the MAC address of this device. 51

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So basically it'll only capture devices 52

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that are directed to my Kali machine. 53

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But this is not what we want. 54

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What we want is to be able to capture all the packets 55

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that are within our range, 56

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even if they are sent to the router 57

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and even if they are set to another device. 58

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So to do this, we need to set the mode 59

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to Monitor mode instead of Managed mode. 60

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So as usual, before you can change the options 61

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of your interface, you have to disable it 62

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and previously, we've seen we can do that 63

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by doing ifconfig, the device name 64

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which is lan0 in my case, down. 65

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Then we can enable monitor mode. 66

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But before we do that, 67

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I'm actually going to run a command 68

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to kill any process 69

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that could interfere with using my interface 70

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in monitor mode. 71

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So the command that I'm gonna run right now 72

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is not mandatory 73

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but running it will actually give you better results 74

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when you come to running the attacks 75

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that you will learn as we go in the course. 76

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So this command is gonna be airman-ng check kill. 77

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Now you'll notice when you're on this command, 78

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it'll actually kill the network manager 79

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that usually runs in here. 80

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So you'll completely lose your internet connection. 81

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But this is no problem 82

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because we will only need to be in monitor mode 83

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when we are running pre-connection attacks 84

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so attacks that do not require us 85

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to connect to any network. 86

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So we actually do not need internet connection 87

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to run any of the attacks that require monitor mode. 88

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Now we're gonna enable monitor mode. 89

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So we're gonna do iwconfig. 90

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Followed by the interface name 91

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that we want to enable monitor mode on 92

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which is lan0. 93

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We're gonna say that I want to change the mode 94

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and I want to change that to monitor. 95

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So very, very simple command. 96

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We're using iwconfig to change the mode. 97

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We're giving the name of the interface 98

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that we want to change its mode. 99

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We're saying I want to change the mode 100

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and I want to set it to monitor mode. 101

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Now, if I hit Enter, you'll see the command will run 102

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with no errors which means the command got executed properly 103

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and finally, we'll need to enable the interface, 104

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again similar to what we did 105

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when we changed the monitor address. 106

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So we just have to do ifconfig lan0 up. 107

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That's done. 108

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Now, if I run iwconfig again, 109

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you'll see that the mode is set to Monitor now. 110

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So basically this interface now can be used 111

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to capture any packet that is within our range, 112

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not only the packets that are directed 113

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to this computer. 114

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That's why in the future you'll see how we can use it 115

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to sniff packets, to analyze them 116

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and even break into networks. 117

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So in the future, 118

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if I say use your interface in monitor mode, 119

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this is what I mean. 120

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You'll basically have to enable monitor mode 121

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as shown in here. 122

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Now, I've also included a YouTube video 123

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in the resources of this lecture 124

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to show an alternative method 125

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to enable monitor mode 126

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just in case you got errors with this method 127

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or you tried to follow something 128

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that I do in the next lectures 129

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and it didn't work. 130

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Then you can come back and try the alternative method. 131

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But if this worked and if monitor mode 132

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is enabled successfully, 133

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then you don't need to watch that video, 134

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you can just continue with the course. 135

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One more thing to keep in mind, 136

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not all wireless adapters support monitor mode. 137

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So for this to work, 138

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you need to make sure 139

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that your actual adapter supports monitor mode. 140

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There are a number of adapters that support that 141

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and I've included another video again in the resources 142

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of me talking about wireless adapters, 143

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hot to pick the best one 144

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and which ones that I recommend and use 145

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when I'm testing the security of networks.