1 1 00:00:00,000 --> 00:00:03,700 Ipconfig, ifconfig and ip. 2 2 00:00:03,700 --> 00:00:06,184 In this video, we're going to cover the ipconfig, 3 3 00:00:06,184 --> 00:00:08,690 ifconfig and ip command line tools 4 4 00:00:08,690 --> 00:00:10,140 and how we use them in maintaining 5 5 00:00:10,140 --> 00:00:11,810 and troubleshooting our networks. 6 6 00:00:11,810 --> 00:00:13,602 First, we have ipconfig. 7 7 00:00:13,602 --> 00:00:16,810 Ipconfig, or IP Configuration, is used to display 8 8 00:00:16,810 --> 00:00:20,020 all of the current TCP IP network configuration values 9 9 00:00:20,020 --> 00:00:23,100 and refreshes the DHCP and DNS settings 10 10 00:00:23,100 --> 00:00:25,140 for a Windows client or server. 11 11 00:00:25,140 --> 00:00:27,380 If you enter ipconfig at the command prompt, 12 12 00:00:27,380 --> 00:00:29,430 you're going to get some basic information back 13 13 00:00:29,430 --> 00:00:31,610 about the TCP IP network configuration 14 14 00:00:31,610 --> 00:00:33,800 in use by your Windows client. 15 15 00:00:33,800 --> 00:00:37,140 In this example, you could see my IPv6 link-local address, 16 16 00:00:37,140 --> 00:00:40,470 my IPv4 address of 10.0.2.15, 17 17 00:00:40,470 --> 00:00:44,260 my subnet mask of 255.255.255.0 18 18 00:00:44,260 --> 00:00:47,740 and my default gateway of 10.0.2.2. 19 19 00:00:47,740 --> 00:00:49,470 There isn't a whole lot of details here, 20 20 00:00:49,470 --> 00:00:51,630 but it does give you the basics. 21 21 00:00:51,630 --> 00:00:54,110 Now, for example, if I entered ipconfig 22 22 00:00:54,110 --> 00:00:58,430 and my IP address was listed as 169.254.132.51, 23 23 00:00:59,690 --> 00:01:01,960 that would indicate I have a DHCP issue, 24 24 00:01:01,960 --> 00:01:04,510 because my computer is now assigned an APIPA address 25 25 00:01:04,510 --> 00:01:07,200 or automatic private IP address value. 26 26 00:01:07,200 --> 00:01:10,040 Now, if this was the case, I could try to get a new IP 27 27 00:01:10,040 --> 00:01:11,435 by releasing and renewing my connection 28 28 00:01:11,435 --> 00:01:13,600 or by rebooting my machine. 29 29 00:01:13,600 --> 00:01:15,650 If that doesn't work, then I can troubleshoot 30 30 00:01:15,650 --> 00:01:19,080 the DHCP server and ensure that it's functioning properly. 31 31 00:01:19,080 --> 00:01:20,880 To release the current IP address, 32 32 00:01:20,880 --> 00:01:23,960 you have to enter the ipconfig /release command 33 33 00:01:23,960 --> 00:01:25,120 and hit ENTER. 34 34 00:01:25,120 --> 00:01:26,500 At this point, you're going to see 35 35 00:01:26,500 --> 00:01:28,560 your IP configuration displayed again, 36 36 00:01:28,560 --> 00:01:31,350 this time showing you have no IPv4 address, 37 37 00:01:31,350 --> 00:01:34,210 no subnet mask and no default gateway assigned. 38 38 00:01:34,210 --> 00:01:36,360 To attempt to get a new DHCP address, 39 39 00:01:36,360 --> 00:01:40,260 you're going to enter ipconfig /renew and then you press ENTER. 40 40 00:01:40,260 --> 00:01:43,480 Now you're going to get an IPv4 address, a subnet mask 41 41 00:01:43,480 --> 00:01:46,460 and a default gateway assigned through the DHCP DORA 42 42 00:01:46,460 --> 00:01:50,000 or discover, offer, request and acknowledge process. 43 43 00:01:50,000 --> 00:01:52,500 Now, you may remember that DHCP actually gives up 44 44 00:01:52,500 --> 00:01:54,420 a bit more information though, right? 45 45 00:01:54,420 --> 00:01:56,450 What is our DNS server's IP address? 46 46 00:01:56,450 --> 00:01:59,320 When is my lease going to be obtained and when does it expire? 47 47 00:01:59,320 --> 00:02:00,800 How can I find my Mac address 48 48 00:02:00,800 --> 00:02:02,250 if I need to know the physical address 49 49 00:02:02,250 --> 00:02:04,640 for some kind of troubleshooting of layer 2 issues? 50 50 00:02:04,640 --> 00:02:06,900 All of these details simply aren't being displayed 51 51 00:02:06,900 --> 00:02:09,500 when I type in ipconfig and hitting ENTER though. 52 52 00:02:09,500 --> 00:02:13,070 So I want to enter ipconfig /all, 53 53 00:02:13,070 --> 00:02:15,368 then I'll be able to see all these additional details 54 54 00:02:15,368 --> 00:02:18,210 about my TCP IP configuration. 55 55 00:02:18,210 --> 00:02:21,780 Now, here I can see my host name, MSEDGEWIN10. 56 56 00:02:21,780 --> 00:02:23,360 I can also see a description of the model 57 57 00:02:23,360 --> 00:02:24,380 of the network adapter 58 58 00:02:24,380 --> 00:02:26,570 or the network interface card I have installed. 59 59 00:02:26,570 --> 00:02:27,860 I can see the physical address 60 60 00:02:27,860 --> 00:02:30,500 and the fact that DHCP is enabled on this machine, 61 61 00:02:30,500 --> 00:02:32,540 as well as the auto configuration being enabled 62 62 00:02:32,540 --> 00:02:34,940 if DHCP fails to get an IP address, 63 63 00:02:34,940 --> 00:02:37,410 which means I can have an APIPA address assigned 64 64 00:02:37,410 --> 00:02:38,290 if I need to. 65 65 00:02:38,290 --> 00:02:40,610 I can also see the IP address and subnet mask, 66 66 00:02:40,610 --> 00:02:43,110 just like I did in the summarized ipconfig version, 67 67 00:02:43,110 --> 00:02:45,410 but now I also see my lease times of the issue 68 68 00:02:45,410 --> 00:02:47,860 and expiration for that DHCP address. 69 69 00:02:47,860 --> 00:02:49,750 I also see my default gateway, 70 70 00:02:49,750 --> 00:02:53,100 my DHCP server and DNS servers' IP addresses. 71 71 00:02:53,100 --> 00:02:54,730 That is a lot of information 72 72 00:02:54,730 --> 00:02:57,150 and it can be really helpful to you as a network technician 73 73 00:02:57,150 --> 00:02:59,010 during your troubleshooting efforts. 74 74 00:02:59,010 --> 00:03:00,795 Next, we have ifconfig. 75 75 00:03:00,795 --> 00:03:03,640 Now, ifconfig stands for interface configuration 76 76 00:03:03,640 --> 00:03:05,690 and it's the command line tool used in Unix, 77 77 00:03:05,690 --> 00:03:09,410 Linux and OS X systems to display IP address information 78 78 00:03:09,410 --> 00:03:11,913 just like we did with ipconfig in Windows. 79 79 00:03:11,913 --> 00:03:13,920 Ipconfig only works in Windows, 80 80 00:03:13,920 --> 00:03:15,530 so if you're going to be working on a Unix, 81 81 00:03:15,530 --> 00:03:18,970 Linux or OS X system, you have to use ifconfig. 82 82 00:03:18,970 --> 00:03:21,860 Now, ifconfig is used to configure your network interfaces 83 83 00:03:21,860 --> 00:03:24,060 and troubleshooting network connectivity issues. 84 84 00:03:24,060 --> 00:03:26,070 If you enter the command, ifconfig by itself 85 85 00:03:26,070 --> 00:03:27,970 and you press ENTER, the system is going to display 86 86 00:03:27,970 --> 00:03:30,440 the status of the currently active interfaces. 87 87 00:03:30,440 --> 00:03:32,490 If you only want to see a single interface though, 88 88 00:03:32,490 --> 00:03:35,247 like en0, you can enter ifconfig en0. 89 89 00:03:36,500 --> 00:03:37,440 Now, if you want to display 90 90 00:03:37,440 --> 00:03:39,410 all the interfaces available on the system, 91 91 00:03:39,410 --> 00:03:41,580 even if those interfaces are currently down, 92 92 00:03:41,580 --> 00:03:43,030 you would enter, ifconfig -a, 93 93 00:03:43,960 --> 00:03:45,440 which is like the /all command 94 94 00:03:45,440 --> 00:03:47,270 that we used inside of Windows. 95 95 00:03:47,270 --> 00:03:50,960 Now, the big difference here between ifconfig and ipconfig 96 96 00:03:50,960 --> 00:03:51,793 is that you're going to get 97 97 00:03:51,793 --> 00:03:54,130 the same amount of information with ifconfig 98 98 00:03:54,130 --> 00:03:56,160 regardless of whether you're using it by itself, 99 99 00:03:56,160 --> 00:03:59,010 with an active interface or with the -a option. 100 100 00:03:59,010 --> 00:04:00,990 There's no brief version of it. 101 101 00:04:00,990 --> 00:04:02,760 The only difference is the number of interfaces 102 102 00:04:02,760 --> 00:04:03,870 that are going to be returned, 103 103 00:04:03,870 --> 00:04:05,580 whether you're saying a single interface, 104 104 00:04:05,580 --> 00:04:08,300 the active interfaces or all the interfaces. 105 105 00:04:08,300 --> 00:04:11,570 Notice here, I typed in ifconfig and under en0, 106 106 00:04:11,570 --> 00:04:15,040 you can see inet6, which list out my IPv6 address. 107 107 00:04:15,040 --> 00:04:17,850 And I see inet, which is my IPv4 address, 108 108 00:04:17,850 --> 00:04:21,410 which is 192.168.1.54. 109 109 00:04:21,410 --> 00:04:23,680 All the other information I need is there too. 110 110 00:04:23,680 --> 00:04:25,440 This includes things like my physical address 111 111 00:04:25,440 --> 00:04:27,750 or Mac address, which is listed as ether, 112 112 00:04:27,750 --> 00:04:29,650 my net mask or subnet mask, 113 113 00:04:29,650 --> 00:04:31,460 which is shown in hexadecimal equivalent, 114 114 00:04:31,460 --> 00:04:35,460 but it's still going to be equivalent to 255.255.255.0 115 115 00:04:35,460 --> 00:04:36,480 like you're used to. 116 116 00:04:36,480 --> 00:04:38,500 It's going to have the broadcast IP for this network 117 117 00:04:38,500 --> 00:04:40,490 and the fact that this network is up. 118 118 00:04:40,490 --> 00:04:43,890 As you can see by default, ifconfig has more details 119 119 00:04:43,890 --> 00:04:46,550 than ipconfig does on a Windows client. 120 120 00:04:46,550 --> 00:04:48,190 Now, if you need additional details, 121 121 00:04:48,190 --> 00:04:51,580 you can enter ifconfig -v and then the interface. 122 122 00:04:51,580 --> 00:04:53,650 The -v stands for verbose, 123 123 00:04:53,650 --> 00:04:55,650 meaning tell me a lot about this thing. 124 124 00:04:55,650 --> 00:04:57,940 So you can see here, I get a lot more details, 125 125 00:04:57,940 --> 00:04:59,280 including the type of the connection, 126 126 00:04:59,280 --> 00:05:00,860 in this case, it's WiFi, 127 127 00:05:00,860 --> 00:05:03,420 the speed of the transmission for the uplinks and downlinks 128 128 00:05:03,420 --> 00:05:05,831 and if the quality of service is enabled or not. 129 129 00:05:05,831 --> 00:05:08,730 Ifconfig can also be used to control the network connection 130 130 00:05:08,730 --> 00:05:11,080 and not simply display information about it. 131 131 00:05:11,080 --> 00:05:13,640 If, for example, I want to turn off that connection, 132 132 00:05:13,640 --> 00:05:15,630 I can use ifconfig down, 133 133 00:05:15,630 --> 00:05:17,700 and this will shut down the network interface. 134 134 00:05:17,700 --> 00:05:19,280 If I use ifconfig up, 135 135 00:05:19,280 --> 00:05:21,300 this will activate that network interface. 136 136 00:05:21,300 --> 00:05:23,410 If you're using static assignments on an interface, 137 137 00:05:23,410 --> 00:05:25,380 you first need to shut down the interface 138 138 00:05:25,380 --> 00:05:27,810 and then set the new address and subnet mask 139 139 00:05:27,810 --> 00:05:29,690 and then you can activate the interface again 140 140 00:05:29,690 --> 00:05:31,910 by using ifconfig up. 141 141 00:05:31,910 --> 00:05:34,200 Remember, ifconfig down turns off 142 142 00:05:34,200 --> 00:05:36,900 your network interface card and if you enter ifconfig up, 143 143 00:05:36,900 --> 00:05:39,560 it'll turn that network interface card back on. 144 144 00:05:39,560 --> 00:05:41,210 These are really important to remember, 145 145 00:05:41,210 --> 00:05:43,100 because if you're not seeing any network connectivity 146 146 00:05:43,100 --> 00:05:44,650 on a Linux client or server, 147 147 00:05:44,650 --> 00:05:46,760 it could be that somebody mistakenly turned off 148 148 00:05:46,760 --> 00:05:49,860 that network card and you just need to enter ifconfig up 149 149 00:05:49,860 --> 00:05:51,410 to turn it back on. 150 150 00:05:51,410 --> 00:05:52,423 Now, as of this recording, 151 151 00:05:52,423 --> 00:05:55,480 ifconfig is considered officially deprecated, 152 152 00:05:55,480 --> 00:05:57,390 which means it's now considered to be obsolete 153 153 00:05:57,390 --> 00:05:59,490 in modern systems and network administrators 154 154 00:05:59,490 --> 00:06:01,390 should instead be using the ip command, 155 155 00:06:01,390 --> 00:06:02,700 which has replaced it. 156 156 00:06:02,700 --> 00:06:05,354 That said, many systems still support ifconfig, 157 157 00:06:05,354 --> 00:06:06,730 at least for now. 158 158 00:06:06,730 --> 00:06:07,940 So you should still learn it 159 159 00:06:07,940 --> 00:06:10,170 in case you're working on an older system. 160 160 00:06:10,170 --> 00:06:12,160 Now, finally, we have ip. 161 161 00:06:12,160 --> 00:06:14,740 The ip command is going to be used to assign an address 162 162 00:06:14,740 --> 00:06:15,860 to a network interface 163 163 00:06:15,860 --> 00:06:18,530 or configure a network interface perimeter on a Unix, 164 164 00:06:18,530 --> 00:06:20,970 Linux or OS X operating system. 165 165 00:06:20,970 --> 00:06:23,060 Ip is a newer tool and it was designed 166 166 00:06:23,060 --> 00:06:25,600 as a modern replacement for ifconfig. 167 167 00:06:25,600 --> 00:06:28,140 The ip command stands for internet protocol 168 168 00:06:28,140 --> 00:06:31,040 and it supports all the same functions as the if command. 169 169 00:06:31,040 --> 00:06:33,770 The ip command though can do a whole lot more. 170 170 00:06:33,770 --> 00:06:36,360 Now, the ip command is actually an entire suite of tools 171 171 00:06:36,360 --> 00:06:39,010 that supports not just configuring your interface address, 172 172 00:06:39,010 --> 00:06:41,180 but also things like routing, creating tunnels 173 173 00:06:41,180 --> 00:06:43,374 and much, much more that is way beyond the scope 174 174 00:06:43,374 --> 00:06:46,320 of this particular course and this exam. 175 175 00:06:46,320 --> 00:06:48,650 Now, instead I want to focus on how we can replace 176 176 00:06:48,650 --> 00:06:50,900 the if command using what we learned 177 177 00:06:50,900 --> 00:06:54,140 with similar features inside of the ip command suite. 178 178 00:06:54,140 --> 00:06:56,380 Now first, if I want to display the configuration 179 179 00:06:56,380 --> 00:07:00,270 of my interfaces, I can simply enter ip a, 180 180 00:07:00,270 --> 00:07:01,950 instead of using ifconfig 181 181 00:07:01,950 --> 00:07:04,240 and this is going to give me the same type of information. 182 182 00:07:04,240 --> 00:07:07,950 The ip a stands for ip address 183 183 00:07:07,950 --> 00:07:10,130 inside of the ip suite of tools. 184 184 00:07:10,130 --> 00:07:12,590 Second, if I need to assign a static IP address 185 185 00:07:12,590 --> 00:07:16,700 to an interface, I can use ip a add, 186 186 00:07:16,700 --> 00:07:20,460 the IP address, dev, whatever device I'm using. 187 187 00:07:20,460 --> 00:07:22,255 For example, this will set the IP address 188 188 00:07:22,255 --> 00:07:26,430 to the device interface known as eth0 or ethernet zero 189 189 00:07:26,430 --> 00:07:30,400 as 192.18.1.123. 190 190 00:07:30,400 --> 00:07:32,254 Third, we can remove that static IP address 191 191 00:07:32,254 --> 00:07:37,254 by entering ip a del, IP address, dev, device 192 192 00:07:38,840 --> 00:07:41,290 and that will be able to take out that IP address 193 193 00:07:41,290 --> 00:07:42,710 from that device. 194 194 00:07:42,710 --> 00:07:45,060 Now, fourth, if we want to change our Mac address, 195 195 00:07:45,060 --> 00:07:47,200 we can conduct Mac spoofing simply 196 196 00:07:47,200 --> 00:07:52,200 by entering ip link set dev, the device, 197 197 00:07:52,450 --> 00:07:55,317 in this case eth0, address, 198 198 00:07:55,317 --> 00:07:57,200 and the Mac address we want to use. 199 199 00:07:57,200 --> 00:08:02,160 In this case, 00:11:22:33:44:55 200 200 00:08:02,160 --> 00:08:04,390 or whatever other Mac address you want to use. 201 201 00:08:04,390 --> 00:08:07,210 Fifth, if you want to make your network interface card operate 202 202 00:08:07,210 --> 00:08:08,470 in promiscuous mode, 203 203 00:08:08,470 --> 00:08:10,850 this will allow it to listen to all the traffic on a network 204 204 00:08:10,850 --> 00:08:13,860 and not just the traffic destined for its own Mac address. 205 205 00:08:13,860 --> 00:08:18,377 To do this, you can enter IP link set dev, your device, 206 206 00:08:20,000 --> 00:08:24,120 eth0 in this case, promisc on. 207 207 00:08:24,120 --> 00:08:26,426 This is really useful if you're setting up a packet sniffer 208 208 00:08:26,426 --> 00:08:30,130 or a packet capture on a Linux client or a server. 209 209 00:08:30,130 --> 00:08:31,690 Finally, if you need to disable 210 210 00:08:31,690 --> 00:08:33,280 or enable a network interface, 211 211 00:08:33,280 --> 00:08:36,503 you can use ip link set eth0 down 212 212 00:08:38,930 --> 00:08:40,780 to turn off eth0 213 213 00:08:40,780 --> 00:08:44,440 or ip link set eth0 up 214 214 00:08:44,440 --> 00:08:45,890 to turn it back on. 215 215 00:08:45,890 --> 00:08:47,710 Now, we really only just scratched the surface 216 216 00:08:47,710 --> 00:08:49,370 of what the ip command can do, 217 217 00:08:49,370 --> 00:08:51,630 but if you're working heavily with Linux systems, 218 218 00:08:51,630 --> 00:08:53,390 I recommend you spend a little time learning 219 219 00:08:53,390 --> 00:08:54,820 more about the ip command 220 220 00:08:54,820 --> 00:08:56,880 and all the different functions it has. 221 221 00:08:56,880 --> 00:08:58,670 For this certification exam though, 222 222 00:08:58,670 --> 00:09:00,730 we covered exactly what you need to know 223 223 00:09:00,730 --> 00:09:03,326 to make sure you're successful on test day. 224 224 00:09:03,326 --> 00:09:05,903 (upbeat music)