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When it comes to networking, 2

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you've probably heard of the term MAC address a lot. 3

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So in this lecture, 4

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I'm gonna cover what do we mean by MAC address, 5

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what it's used for, and how to change it. 6

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(dramatic music) 7

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(loud banging) 8

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MAC address stands for Media Access Control, 9

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it's a permanent, physical, and unique address 10

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assigned to network interfaces 11

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by the device manufacturer. 12

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So whether you have a wireless card, 13

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or a wired, or Ethernet card, 14

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each one of these network cards 15

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come with a specific address that is unique to this card. 16

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So there is no two devices in the world 17

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that would have the same MAC address. 18

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And this address will always be the same 19

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to this specific device, 20

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even if you unplug it from your computer, 21

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connect it to another computer, 22

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then this network device will always have the same address. 23

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So you might already know that the IP address 24

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is used in the internet to identify computers, 25

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and communicate between devices on the internet. 26

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The MAC address is used within the network 27

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to identify devices and transfer data between devices. 28

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So each piece of data or packet 29

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that is sent within the network 30

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contains a source MAC and a destination MAC. 31

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Therefore, this packet would flow 32

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from the source MAC to the destination MAC. 33

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So because this is a physical unique address 34

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to each interface, to each network device, 35

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and because it is used to identify devices, 36

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then changing it will make you anonymous on the network. 37

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Not only that, but the MAC address is often used 38

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by filters to prevent or allow devices 39

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to connect to networks, 40

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and do specific tasks on the network. 41

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So being able to change your MAC address 42

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to another device's MAC address 43

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will allow you to impersonate this device 44

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and allow you to do things 45

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that you might not be able to do. 46

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So you'd be able to bypass filters, 47

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or connect to networks that only specific devices 48

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with specific MAC addresses can connect to, 49

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and you will also be able to hide your identity. 50

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Now changing the MAC address is very, very simple, 51

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so let me show you how to do that. 52

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First of all, I'm going to use the ifconfig command 53

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to list all the network interfaces 54

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available on my Kali machine. 55

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What I mean by network interface is any device 56

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that allow us to connect to a network. 57

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So an example is a Wi-Fi card, 58

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or an Ethernet card, and so on. 59

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So you can see first of all we have eth0, 60

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and this is a virtual interface created by virtual box 61

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when we set Kali to use iNet network. 62

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So you can see the interface name is eth0, 63

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you can see it has an IP address because like I said, 64

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it's connected to a network. 65

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So if we go here, we can see it saying Wired Connected. 66

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So this is the interface that represents the wired network 67

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that Kali is connected to, 68

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which is actually a virtual NAT network. 69

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You can also see the netmask, the broadcast, 70

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and a really important piece of information, 71

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which is the ether. 72

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This is the MAC address of this virtual interface. 73

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Now, you can see similar information 74

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for my other two interfaces, the lo and the lan0. 75

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The only thing is you can see for both of these interfaces, 76

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we do not have an IP address. 77

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And the main reason for that 78

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is because none of these interfaces 79

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is connected to a network. 80

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Now lo is the default interface created by Linux, 81

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and lan0 is my real wireless adapter, 82

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so I can use it to connect to Wi-Fi networks. 83

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But if I go on the network in here, 84

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you'll see Wi-Fi is not connected, 85

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because I actually didn't connect to any network, 86

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and that's why it does not have an IP address. 87

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Now, this doesn't matter because what we want to do 88

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is to just change the MAC address, 89

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which again, is shown here under the ether part, 90

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so similar to what you're seeing here for eth0. 91

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Now, in order to change any of the values 92

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that you see in here, 93

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you have to first disable the interface. 94

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So in this example, we want to change the MAC address, 95

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so that is represented by the ether 96

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and the value is right here. 97

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So in order to disable an interface, 98

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we're gonna do ifconfig followed by the interface name, 99

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which is lan0 in my example, followed by down to disable it. 100

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Now, if I hit Enter, you'll see 101

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the command runs with no errors, 102

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so it means that it got executed properly. 103

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And the next thing that we need to do, 104

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is to change the option that we want to change. 105

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And in this example, we want to change the ether, 106

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which is the MAC address. 107

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So first, we're gonna type ifconfig, 108

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we're gonna type the interface that we want to change, 109

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one of its options, then we're gonna type 110

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the option that we want to change. 111

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And what we want to change is the hardware address, 112

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so we're gonna do hw ether. 113

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Then we're gonna give it the address 114

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that we want to change the MAC address to. 115

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So for example, I'm gonna use 00:11:22:33:44:55. 116

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Very, very simple command, 117

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we're doing ifconfig lan0 to select the interface 118

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that we want to change its option, 119

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we wanna set the hardware address, 120

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and we wanna set this address to this specific address. 121

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So you can use any address that you want, 122

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following the same format shown here. 123

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Just make sure your address starts with 00. 124

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So I'm gonna hit Enter and again, 125

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we don't see any error messages, 126

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so it means the command got executed properly. 127

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And finally, we just need to enable the interface 128

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because we disabled it, by doing, ifconfig lan0 down, 129

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so we just need to do, ifconfig lan0 up, to enable it. 130

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Now the interface is enabled, 131

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and if we do ifconfig again, 132

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and look at the ether part in here, 133

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you can see that it is changed 134

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to the MAC address that we specified. 135

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Now, this is done, and your MAC address has changed. 136

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Now, you can go ahead and start using the interface 137

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and it'll appear to have this MAC address 138

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instead of its original MAC address. 139

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And like I said, this can be useful in so many scenarios. 140

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Now, keep in mind, the MAC address will revert back 141

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to the original one once you restart the computer, 142

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because we're only changing the MAC address in memory, 143

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we're not really changing the physical MAC address. 144

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But if your MAC address is resetting 145

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to the original one without restarting, 146

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then something is going wrong. 147

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And it's probably happening because your network manager 148

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is resetting the MAC address. 149

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Not everybody will face this issue, 150

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so I'm not gonna cover it in this lecture, 151

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but if you face this issue, 152

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if your MAC address goes back to the original one 153

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without restarting the computer, 154

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then check out the YouTube video 155

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in the resources of this lecture, 156

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it'll show you how to fix this issue.