1 00:00:00,000 --> 00:00:02,230 [No audio] 2 00:00:02,230 --> 00:00:04,546 IP Address Assigned but not reachable. 3 00:00:04,738 --> 00:00:08,218 Okay, so I'm sure some of you probably have experienced 4 00:00:08,254 --> 00:00:11,874 the issue where you do see the IP address but 5 00:00:11,912 --> 00:00:15,834 you cannot connect to the machine through SSH or 6 00:00:15,872 --> 00:00:18,510 from another machine, of course using SSH. 7 00:00:19,370 --> 00:00:21,990 So that's where we are going to focus. 8 00:00:22,100 --> 00:00:27,342 And this lecture is about troubleshooting issues that focuses on 9 00:00:27,416 --> 00:00:30,438 how and what could be the reason the machine has 10 00:00:30,464 --> 00:00:34,074 an IP address, but we still cannot connect or still 11 00:00:34,112 --> 00:00:38,250 cannot go outside of that machine to other machines. 12 00:00:38,630 --> 00:00:42,078 So the troubleshooting steps that we could go over 13 00:00:42,164 --> 00:00:45,318 is the first one is we'll check if you 14 00:00:45,344 --> 00:00:49,294 are on the correct network, by running ifconfig. 15 00:00:49,462 --> 00:00:53,626 What does it mean? If you have multiple interfaces, 16 00:00:53,818 --> 00:00:56,646 so let's say if your machine has three 17 00:00:56,708 --> 00:00:59,658 interfaces instead of one, then you need to 18 00:00:59,684 --> 00:01:02,926 make sure you are picking the right interface 19 00:01:03,058 --> 00:01:06,019 where you have assigned the IP address. 20 00:01:07,069 --> 00:01:11,698 Because the network team, now I'm talking about Virtualization 21 00:01:11,794 --> 00:01:15,906 team or the network team, what they do is 22 00:01:16,028 --> 00:01:21,618 if there are cables connected in the back of 23 00:01:21,644 --> 00:01:25,482 a computer, then they will give an IP address 24 00:01:25,556 --> 00:01:28,026 to one cable and not the other two. 25 00:01:28,148 --> 00:01:30,562 So make sure the cable that is connected 26 00:01:30,586 --> 00:01:33,894 to the correct interface is the interface is 27 00:01:33,932 --> 00:01:36,714 actually being configured for that IP address. 28 00:01:36,812 --> 00:01:38,718 So we'll take a look at that in a 29 00:01:38,744 --> 00:01:41,130 little bit when we log into a Linux machine. 30 00:01:41,630 --> 00:01:43,098 Also check to see if you got 31 00:01:43,124 --> 00:01:45,510 the right subnet mask and gateway. 32 00:01:46,970 --> 00:01:49,518 You always get the subnet information and 33 00:01:49,544 --> 00:01:51,670 gateway information from your network engineer. 34 00:01:51,730 --> 00:01:53,562 So make sure when you are talking to 35 00:01:53,576 --> 00:01:56,214 your network engineer, make sure they have given 36 00:01:56,252 --> 00:01:59,446 you the correct subnet and correct gateway. 37 00:01:59,518 --> 00:02:03,618 There might be a typo, there might be a 38 00:02:03,644 --> 00:02:06,234 fat finger when they sent you an email. 39 00:02:06,392 --> 00:02:10,422 Instead of like 192.168.1.1 gateway, they probably give 40 00:02:10,436 --> 00:02:14,014 it 2, and then you are just trying and figuring 41 00:02:14,062 --> 00:02:16,340 out so hard, but it's just not working. 42 00:02:17,390 --> 00:02:19,114 Then ping the gateway. 43 00:02:19,162 --> 00:02:20,874 If you are on the right gateway, then 44 00:02:20,912 --> 00:02:23,466 simply ping that gateway just to make sure 45 00:02:23,528 --> 00:02:26,070 if you could reach that gateway. 46 00:02:26,750 --> 00:02:29,518 If you cannot reach the gateway, then of course there's 47 00:02:29,554 --> 00:02:31,818 something wrong with the gateway or something wrong with the 48 00:02:31,844 --> 00:02:34,220 routing, which we'll take a look in a bit. 49 00:02:34,550 --> 00:02:37,294 Check if the gateway is assigned. 50 00:02:37,462 --> 00:02:40,830 So if your configuration is correct, then 51 00:02:40,880 --> 00:02:43,014 the gateway will be assigned itself. 52 00:02:43,112 --> 00:02:47,658 But if it is incorrect, then most likely you will 53 00:02:47,684 --> 00:02:50,670 have a problem where the gateway will not show up. 54 00:02:50,780 --> 00:02:56,266 So a gateway is like a gate which actually transport 55 00:02:56,338 --> 00:02:59,158 all your traffic from your machine to another machine. 56 00:02:59,254 --> 00:03:01,938 So if the gateway is not set in the 57 00:03:01,964 --> 00:03:04,160 routing table, then you're going to have a problem. 58 00:03:04,550 --> 00:03:07,398 Check with the network team if the correct vLAN is 59 00:03:07,424 --> 00:03:09,978 assigned on the switch side. What does it mean? 60 00:03:10,124 --> 00:03:12,334 It means that every network 61 00:03:12,442 --> 00:03:14,480 IP addresses are different, right? 62 00:03:14,810 --> 00:03:18,798 So the IP address that is given to you 63 00:03:18,884 --> 00:03:23,022 is actually assigned to the correct IP range, which 64 00:03:23,036 --> 00:03:26,238 is referred to as vLAN on the switching side, 65 00:03:26,384 --> 00:03:29,190 if that is assigned to the correct vLAN. 66 00:03:29,930 --> 00:03:35,232 If you have given an IP address, for example, 192.168.1.12, 67 00:03:35,232 --> 00:03:38,502 and that in the back, on the switch side, 68 00:03:38,576 --> 00:03:43,974 it is configured for IP address 10.172.16.1, 69 00:03:44,132 --> 00:03:46,134 then no matter how many times 70 00:03:46,172 --> 00:03:47,550 you try, it will not work. 71 00:03:47,660 --> 00:03:49,738 Your computer will be okay, your setting 72 00:03:49,774 --> 00:03:51,834 on your computer will be okay, but 73 00:03:51,932 --> 00:03:54,714 the network switch side is not okay. 74 00:03:54,812 --> 00:03:58,234 So make sure when you talk to your networking folks, 75 00:03:58,402 --> 00:04:01,374 tell them that you are using this IP address. 76 00:04:01,532 --> 00:04:04,662 Please make sure it is actually associated to 77 00:04:04,676 --> 00:04:07,700 the correct vLAN on the switch side. 78 00:04:08,810 --> 00:04:14,614 Run tools like ethtool or mii-tool to check the NIC status. 79 00:04:14,722 --> 00:04:17,442 So of course, if you are not at 80 00:04:17,456 --> 00:04:21,586 the data center, you cannot really physically verify 81 00:04:21,658 --> 00:04:23,454 if the cable is connected right. 82 00:04:23,552 --> 00:04:27,750 You cannot see the blinking light on the port. 83 00:04:27,920 --> 00:04:30,714 So there are tools that could tell you if the 84 00:04:30,752 --> 00:04:34,134 link status is up or down and those tools are 85 00:04:34,172 --> 00:04:38,540 ethtool or mii-tool, which we'll check it in a little bit. 86 00:04:39,110 --> 00:04:41,910 Also run the command ifup space the 87 00:04:41,960 --> 00:04:44,526 interface command to bring up the NIC port. 88 00:04:44,648 --> 00:04:47,058 Or you could just do ifdown and 89 00:04:47,084 --> 00:04:49,906 then ifup just to reset the interface. 90 00:04:50,038 --> 00:04:52,602 Maybe it was not set up correctly and 91 00:04:52,616 --> 00:04:56,406 you probably have to restart. Restart network system 92 00:04:56,468 --> 00:04:59,070 of course, which will do everything for you. 93 00:04:59,240 --> 00:05:02,562 If things are not working, something is wrong, 94 00:05:02,696 --> 00:05:05,958 if you're doing a systemctl restart network, and 95 00:05:05,984 --> 00:05:08,514 there is something wrong with the network setting, it 96 00:05:08,552 --> 00:05:11,780 will tell you where exactly the problem is. 97 00:05:12,590 --> 00:05:15,138 Check on the status of NIC by 98 00:05:15,164 --> 00:05:18,286 running ifconfig or ip addr command. 99 00:05:18,478 --> 00:05:21,486 We know that we ran that command many times, but 100 00:05:21,608 --> 00:05:25,170 on the NIC itself, you probably see the IP address, 101 00:05:25,280 --> 00:05:28,350 you probably see it is assigned and NIC is up, 102 00:05:28,460 --> 00:05:31,194 but the actual interface, NIC, is probably 103 00:05:31,232 --> 00:05:33,882 not showing up as UP, meaning up. 104 00:05:34,016 --> 00:05:36,620 So we'll check that in a little bit. 105 00:05:37,130 --> 00:05:39,706 Also check to see if the IP 106 00:05:39,838 --> 00:05:43,134 is assigned to some other device. Okay. 107 00:05:43,172 --> 00:05:44,670 Yeah, that happens to me too. 108 00:05:44,720 --> 00:05:47,958 In the past, if you are trying to assign an 109 00:05:47,984 --> 00:05:52,230 IP, especially static IP, to your machine and everything looks 110 00:05:52,280 --> 00:05:56,300 good but still having a problem, then there could be 111 00:05:56,930 --> 00:06:00,354 a possibility that the IP that is given to you 112 00:06:00,392 --> 00:06:03,586 has already been assigned to another machine. 113 00:06:03,778 --> 00:06:04,858 People make mistakes. 114 00:06:04,894 --> 00:06:07,674 That's why maybe the engineer, the network engineer has given 115 00:06:07,712 --> 00:06:11,242 you that IP, which is a duplicate IP 116 00:06:11,326 --> 00:06:13,678 and it's going to cause IP conflict. 117 00:06:13,774 --> 00:06:16,254 So what will happen is, you will try to bring 118 00:06:16,292 --> 00:06:19,518 your IP address up and it will come up, but 119 00:06:19,544 --> 00:06:25,400 it won't work because it's already up by another computer. 120 00:06:26,150 --> 00:06:28,206 Your IP address will only work 121 00:06:28,268 --> 00:06:31,578 when the other computer shuts down. 122 00:06:31,724 --> 00:06:34,726 So again, make sure there's no IP conflict. 123 00:06:34,918 --> 00:06:39,174 And sometimes there are firewalls rules in place at the 124 00:06:39,212 --> 00:06:43,818 operating system level or at the network switch level 125 00:06:43,964 --> 00:06:47,634 which will prevent you to ping or SSH from one 126 00:06:47,672 --> 00:06:50,818 machine to another. So make sure your firewall is turned 127 00:06:50,854 --> 00:06:54,358 off at the OS level as well as the firewall 128 00:06:54,394 --> 00:06:58,326 configuration is done right at the networking level. So again 129 00:06:58,388 --> 00:07:01,674 bring it up with the networking team, ask them if 130 00:07:01,712 --> 00:07:04,938 there are any issues with the firewall that has been 131 00:07:05,084 --> 00:07:08,382 sitting in the middle of one computer which you're working 132 00:07:08,456 --> 00:07:11,180 to another computer where you're trying to reach to. 133 00:07:11,585 --> 00:07:13,734 So here are a few troubleshooting steps, let's go 134 00:07:13,772 --> 00:07:17,600 into our Linux machine and we will actually 135 00:07:17,600 --> 00:07:20,370 [No audio] 136 00:07:20,370 --> 00:07:23,015 go through all these items. 137 00:07:23,015 --> 00:07:26,349 [No audio] 138 00:07:26,349 --> 00:07:27,954 Okay. This is my Linux machine. 139 00:07:28,002 --> 00:07:30,854 I have it up and running, and I am logged in 140 00:07:30,892 --> 00:07:35,558 as root. So now let's see, first check if you are 141 00:07:35,584 --> 00:07:39,882 on the correct network interface. So if I do ifconfig 142 00:07:40,026 --> 00:07:44,774 or if I do ip addr, address, you'll see 143 00:07:44,812 --> 00:07:47,654 all the interfaces that you have available. Right now you see 144 00:07:47,654 --> 00:07:54,038 you have enp0s3, lo, which is the loop back. This 145 00:07:54,064 --> 00:07:55,598 is something you don't have to worry about. 146 00:07:55,624 --> 00:07:57,662 You could ignore it and the same way you don't have 147 00:07:57,676 --> 00:08:03,365 to worry about the virtual bridge adapter. If you had enp0s3 here, 148 00:08:03,365 --> 00:08:07,550 and you had another one enp0s4, 149 00:08:07,720 --> 00:08:11,918 s5, three of them, then you are trying to probably 150 00:08:12,004 --> 00:08:16,994 assign this IP 192.168.1.36 or 37 whatever the IP is given 151 00:08:17,032 --> 00:08:20,246 to you, you're probably assigning to s3. Well, 152 00:08:20,308 --> 00:08:26,358 in fact it should go to enp0s4. 153 00:08:26,470 --> 00:08:29,598 If that's the case, make sure you are assigning 154 00:08:29,634 --> 00:08:32,977 it to the correct one. How do you know 155 00:08:33,124 --> 00:08:34,994 you're assigning it to the correct one? 156 00:08:35,032 --> 00:08:37,926 Well, the tools that you can use to check the status 157 00:08:37,998 --> 00:08:40,669 if the Link status is up or not is by running 158 00:08:40,720 --> 00:08:46,525 the ethtool or mii-tool. So if I have two 159 00:08:46,587 --> 00:08:55,381 interfaces I could do ethtools enp0s3. When I hit Enter, 160 00:08:55,456 --> 00:09:01,926 you'll see right here tells me the speed of this interface, 161 00:09:02,118 --> 00:09:08,906 and somewhere here it will tell you something about Link, yes. 162 00:09:08,968 --> 00:09:11,078 All the way at the bottom, you see it says Link 163 00:09:11,164 --> 00:09:16,346 detected, it says yes. It means the cable in the back 164 00:09:16,408 --> 00:09:22,610 is connected. Of course we are using virtualization Linux machine but 165 00:09:22,660 --> 00:09:26,466 it will still read it as if the cable is connected 166 00:09:26,598 --> 00:09:29,426 so you see right here it says Link detected: yes, perfect. 167 00:09:29,548 --> 00:09:36,130 If you had enp0s4, or s5, and you had linked 168 00:09:36,310 --> 00:09:39,666 it coming up as no then you know right away 169 00:09:39,728 --> 00:09:43,926 okay, this IP address is not set up for that 170 00:09:43,988 --> 00:09:46,386 interface, so you will assign it to the correct one. 171 00:09:46,508 --> 00:09:50,902 Now the question is, what if you have three interfaces, 172 00:09:50,986 --> 00:09:54,250 and all of them show up as link detected? 173 00:09:54,310 --> 00:09:58,774 Yes then basically you have to go through the round robin 174 00:09:58,822 --> 00:10:01,942 thing, you have to assign the IP to the first interface, 175 00:10:02,026 --> 00:10:05,022 then the second, and then the third, and then see if 176 00:10:05,036 --> 00:10:10,494 it works or not. Otherwise if you want to find out 177 00:10:10,532 --> 00:10:13,902 the easier way, you have to talk to your networking guy 178 00:10:14,036 --> 00:10:21,370 to find out which cable or which port has which vLAN. 179 00:10:21,490 --> 00:10:23,586 I'm sure every company would have 180 00:10:23,648 --> 00:10:26,120 a specific way of doing things. 181 00:10:27,350 --> 00:10:29,958 Sometimes companies that I've work is 182 00:10:30,044 --> 00:10:31,798 very good in the documentation. 183 00:10:31,954 --> 00:10:36,822 They actually have spreadsheet which would tell which port on 184 00:10:36,836 --> 00:10:40,626 the switch on the network switch goes to which port 185 00:10:40,808 --> 00:10:44,686 on the server, because a server could have multiple ports, 186 00:10:44,698 --> 00:10:47,118 so it will tell you exactly where it's going. 187 00:10:47,264 --> 00:10:49,674 Also, if your networking team is not the ones 188 00:10:49,712 --> 00:10:52,998 that doing all this work of running cables, then 189 00:10:53,024 --> 00:10:56,802 you probably have an install team or data center 190 00:10:56,876 --> 00:11:00,258 team that will perform all these tasks for you. 191 00:11:00,284 --> 00:11:03,042 They are the one who will have that spreadsheet or 192 00:11:03,056 --> 00:11:06,798 the information that would tell you exactly which cable is 193 00:11:06,824 --> 00:11:10,966 going to which port and which port, or which cable 194 00:11:11,098 --> 00:11:14,840 has which vLAN assigned. So check with them. 195 00:11:15,290 --> 00:11:16,938 Then check to see if you got 196 00:11:16,964 --> 00:11:18,946 the right subnet mask or gateway. 197 00:11:19,018 --> 00:11:23,974 So even if you do ifconfig, you'll notice that your subnet mask 198 00:11:24,022 --> 00:11:29,466 for this interface, net mask is 255.255.255.0. 199 00:11:29,528 --> 00:11:31,246 Okay, you're looking at it and you're 200 00:11:31,258 --> 00:11:33,502 like, okay, I have the gate. 201 00:11:33,586 --> 00:11:34,642 There's something that masked. 202 00:11:34,726 --> 00:11:37,880 Then why I cannot connect to this IP address? 203 00:11:38,270 --> 00:11:40,266 Or why cannot I go from 204 00:11:40,328 --> 00:11:42,210 this machine to another machine? 205 00:11:42,830 --> 00:11:45,390 Probably your subnet mask that is 206 00:11:45,440 --> 00:11:47,374 given to you is incorrect. 207 00:11:47,482 --> 00:11:52,734 Maybe it's 255.255.254, 253, depending on 208 00:11:52,772 --> 00:11:54,526 how your network is configured. 209 00:11:54,658 --> 00:11:57,942 So again, confirm with your networking team 210 00:11:58,076 --> 00:12:01,078 that you got the correct subnet mask. 211 00:12:01,174 --> 00:12:03,382 Now, please remember this whole scenario. 212 00:12:03,406 --> 00:12:06,334 I'm talking about the static IP assignment. 213 00:12:06,442 --> 00:12:10,998 If you are on the DHCP IP assignment, which 214 00:12:11,024 --> 00:12:15,486 is not static, then your computer, your operating system, 215 00:12:15,548 --> 00:12:19,470 will pick up the correct net mask itself. 216 00:12:19,580 --> 00:12:21,258 You don't have to worry about it. 217 00:12:21,344 --> 00:12:24,140 Also it will pick up the gateway itself. 218 00:12:24,530 --> 00:12:27,882 But in the static world, you do have 219 00:12:27,896 --> 00:12:30,982 to specify the net mask and the gateway. 220 00:12:31,066 --> 00:12:33,198 So, as I said, make sure you are 221 00:12:33,224 --> 00:12:36,274 given the correct net mask and correct gateway. 222 00:12:36,382 --> 00:12:38,566 Now, how do you check the gateway? 223 00:12:38,698 --> 00:12:40,974 The command that I use to check 224 00:12:41,012 --> 00:12:46,851 the gateway is netstat -rnv. 225 00:12:47,130 --> 00:12:50,674 This will tell me right here, the first line. 226 00:12:50,772 --> 00:12:52,874 First of all, right up here it's telling 227 00:12:52,922 --> 00:12:56,750 you, these are the labels or the columns. 228 00:12:56,870 --> 00:12:58,742 Then right here, the first column is telling 229 00:12:58,766 --> 00:13:01,714 you all the traffic which is coming from 230 00:13:01,752 --> 00:13:04,106 whichever the IP in this machine. 231 00:13:04,298 --> 00:13:07,826 That's why it's given 0.0.0.0. 232 00:13:08,230 --> 00:13:10,890 All that traffic should go to the gateway 233 00:13:10,950 --> 00:13:17,030 192.168.1.1, and that gateway is telling it, 234 00:13:17,140 --> 00:13:19,394 and all that traffic should be 235 00:13:19,432 --> 00:13:24,640 routed through the interface enp0s3. 236 00:13:24,970 --> 00:13:26,870 That's how you see it. 237 00:13:26,920 --> 00:13:28,898 And then you'll see right here, all the 238 00:13:28,924 --> 00:13:35,406 traffic of 192.168.1.0, should go to this gateway, 239 00:13:35,538 --> 00:13:39,246 which is eventually were routed to this gateway. 240 00:13:39,378 --> 00:13:44,810 And then it should have a subnet mask of 255.255.255.0. 241 00:13:44,980 --> 00:13:47,198 The last one, you could ignore it, because as I 242 00:13:47,224 --> 00:13:50,226 said, this is for the bridge, virtual bridge adapter. 243 00:13:50,358 --> 00:13:53,222 You could even disable that adapter if you want. 244 00:13:53,296 --> 00:13:55,574 But anyway, let's not get into this one. 245 00:13:55,672 --> 00:13:58,010 I don't want to confuse you. All right. 246 00:13:58,060 --> 00:14:02,114 So make sure the subnet masking gateway is correct. 247 00:14:02,272 --> 00:14:04,178 Then next thing is, if you think it 248 00:14:04,204 --> 00:14:07,442 is correct and it's given to you, by the 249 00:14:07,456 --> 00:14:10,022 network folks the right gateway then ping it. 250 00:14:10,156 --> 00:14:17,022 So ping 192.168.1.1. If you are getting a response 251 00:14:17,046 --> 00:14:20,738 back which is say 64 bytes, and you are getting 252 00:14:20,764 --> 00:14:25,974 the ICMP response back, it means the gateway is listening, 253 00:14:26,022 --> 00:14:29,022 and it is responding, and it is up. This gateway, 254 00:14:29,106 --> 00:14:31,914 in the real corporate world, this is the IP assigned, 255 00:14:31,962 --> 00:14:37,154 most likely assigned it to the networking switch where all 256 00:14:37,192 --> 00:14:39,066 the computers are connected. 257 00:14:39,258 --> 00:14:40,814 So you pinged it, it works. 258 00:14:40,972 --> 00:14:43,410 Check if the gateway is assigned. 259 00:14:43,590 --> 00:14:45,290 I just covered that by running 260 00:14:45,340 --> 00:14:49,842 the command netstat -rnv. 261 00:14:49,926 --> 00:14:51,998 If you do not see that gateway that 262 00:14:52,024 --> 00:14:55,106 is given to you assigned here then you 263 00:14:55,168 --> 00:15:01,398 probably have incorrect configuration in your configuration file. 264 00:15:01,434 --> 00:15:03,510 And where is that configuration file? 265 00:15:03,690 --> 00:15:07,550 It's an /etc/sysconfig/network-scripts, and if you do 266 00:15:07,600 --> 00:15:13,178 ifcfg-enp0s3, you'll see this is the 267 00:15:13,204 --> 00:15:19,094 static configuration file setting and this will tell you right 268 00:15:19,132 --> 00:15:24,278 here how the configuration should be set up and it 269 00:15:24,304 --> 00:15:26,150 should have a gateway in here as well. 270 00:15:26,200 --> 00:15:28,406 Right now you don't see it because 271 00:15:28,588 --> 00:15:31,302 the type is set up for DHCP. 272 00:15:31,446 --> 00:15:32,834 That is why you don't see it. 273 00:15:32,872 --> 00:15:34,418 If you want to have a static, you 274 00:15:34,444 --> 00:15:37,120 will have to add that gateway in there. 275 00:15:38,530 --> 00:15:42,002 Next one is, check with the network team 276 00:15:42,076 --> 00:15:45,570 if the correct vLAN is assigned on the switch, there isn't 277 00:15:45,630 --> 00:15:47,954 any commands that you would have to run for that. 278 00:15:48,052 --> 00:15:49,910 You would basically have to pick up a phone 279 00:15:49,960 --> 00:15:53,090 or send an email to your network engineer and 280 00:15:53,200 --> 00:15:56,586 ask them that you are on the correct vLAN. 281 00:15:56,778 --> 00:16:01,360 Then check their tool ethtool or mii-tool. 282 00:16:01,750 --> 00:16:03,266 I already covered that. 283 00:16:03,388 --> 00:16:08,738 But to just go quickly run ethtool enp0s3 284 00:16:08,824 --> 00:16:12,618 on your interface to check the status of your interface 285 00:16:12,654 --> 00:16:16,274 if you want to know the speed of that port, 286 00:16:16,432 --> 00:16:19,394 if you want to know whether it's full duplex, half 287 00:16:19,432 --> 00:16:23,118 duplex, the link status you will run that command. 288 00:16:23,214 --> 00:16:30,398 The other command is mii-tool enps03, and 289 00:16:30,424 --> 00:16:36,170 you will see enp, did I type it correctly? 290 00:16:36,170 --> 00:16:38,656 [No audio] 291 00:16:38,656 --> 00:16:43,580 enp, oh no, interface is correct, enp0s3. 292 00:16:43,970 --> 00:16:46,506 Now you'll see here it says no 293 00:16:46,506 --> 00:16:51,030 no autonegotiation, thousand which is one gig of 294 00:16:51,080 --> 00:16:54,942 interface, flow-control, and link is okay. 295 00:16:55,016 --> 00:16:58,230 This is the same link okay as if you see here. 296 00:16:58,280 --> 00:17:00,320 Is link detected? Yes. 297 00:17:01,370 --> 00:17:03,762 And the last one if you are still trying everything, 298 00:17:03,836 --> 00:17:06,582 you can always try to reboot your machine or you 299 00:17:06,596 --> 00:17:13,819 could just simply do systemctl or system control restart 300 00:17:13,964 --> 00:17:18,622 network and this will again go back to your configuration 301 00:17:18,704 --> 00:17:21,498 file, find out if there are any issues. 302 00:17:21,584 --> 00:17:25,122 If there are, it will notify you. Check on the 303 00:17:25,136 --> 00:17:27,944 status of the NIC by running ifconfig command. 304 00:17:28,018 --> 00:17:31,710 We have covered that. Also we could check if it is up 305 00:17:31,760 --> 00:17:36,821 and down by looking at one specific thing that I was going 306 00:17:36,836 --> 00:17:43,722 to show you is, right here it says enp0s3. 307 00:17:43,796 --> 00:17:45,800 And you see right here it says up. 308 00:17:46,970 --> 00:17:50,094 If it is not up, sometimes what happens is 309 00:17:50,192 --> 00:17:52,938 you probably do see that the IP assigned and 310 00:17:52,964 --> 00:17:56,046 everything is working and something that mask is correct. 311 00:17:56,108 --> 00:17:59,382 But you don't see this little thing says UP right here. 312 00:17:59,516 --> 00:18:02,634 So in order for you to bring this up, then 313 00:18:02,672 --> 00:18:12,508 you could run the command ifconfig enp0s3 up, 314 00:18:12,508 --> 00:18:15,434 and then when you run ifconfig 315 00:18:15,482 --> 00:18:18,010 again, then you will see actually this will come up 316 00:18:18,060 --> 00:18:21,502 as UP, and it will also second thing you have 317 00:18:21,516 --> 00:18:24,466 to check is it's RUNNING, right here, 318 00:18:24,528 --> 00:18:27,394 it's RUNNING. And if you see here, it 319 00:18:27,432 --> 00:18:30,970 says UP BROADCAST, but it is not running. 320 00:18:31,080 --> 00:18:36,058 So make sure it is running and then check to 321 00:18:36,084 --> 00:18:39,790 see if the IP is assigned to some other devices. 322 00:18:40,290 --> 00:18:43,114 And the only way you could do that is if 323 00:18:43,152 --> 00:18:46,210 you go to another machine and ping that IP address 324 00:18:46,260 --> 00:18:50,366 that you're trying to assign, see if it exists. 325 00:18:50,438 --> 00:18:52,798 But if it is pingable, then try to 326 00:18:52,824 --> 00:18:54,814 log into it and see if you're getting 327 00:18:54,912 --> 00:18:57,310 landing into the right machine or not. 328 00:18:57,480 --> 00:19:00,074 And the last one I said turn off the Firewall. 329 00:19:00,122 --> 00:19:01,402 This is one of the things that you 330 00:19:01,416 --> 00:19:07,810 could rule out by doing systemctl stop, 331 00:19:07,920 --> 00:19:10,560 in the newer version is firewalld. 332 00:19:11,550 --> 00:19:19,620 In the older version, it's a service iptable stop. 333 00:19:20,670 --> 00:19:22,702 And it is telling you, since this is 334 00:19:22,716 --> 00:19:24,754 a newer version of operating system, it's saying 335 00:19:24,792 --> 00:19:28,330 I'm redirecting you to systemctl, and in there 336 00:19:28,380 --> 00:19:33,240 you should use this stop iptable service. 337 00:19:34,770 --> 00:19:39,322 So if I use that, I'm sure it 338 00:19:39,516 --> 00:19:45,098 still exists, but it is deprecated not loaded. 339 00:19:45,134 --> 00:19:47,978 Meaning it is there, but it is not loaded. 340 00:19:48,014 --> 00:19:50,830 Failed to stop because it's not up and running. Why? 341 00:19:50,880 --> 00:19:53,338 Because we have actually started running Firewalld 342 00:19:53,364 --> 00:19:55,582 now. It's a newer version that runs on in 343 00:19:55,596 --> 00:19:59,220 your CentOS or Redhat operating system. 344 00:19:59,670 --> 00:20:02,098 So these are the pretty much the steps that 345 00:20:02,124 --> 00:20:05,462 you need to take in the corporate environment. 346 00:20:05,606 --> 00:20:10,354 And I am very sure, very hopeful if you go 347 00:20:10,392 --> 00:20:15,238 through all these steps of troubleshooting, the IP address when 348 00:20:15,264 --> 00:20:17,638 it is actually shows up, that it is up and 349 00:20:17,664 --> 00:20:20,146 running, but somehow you cannot reach it. 350 00:20:20,268 --> 00:20:23,398 That's why probably one of the reasons, I'm sure when 351 00:20:23,424 --> 00:20:25,294 you go through it, you'll find it right there. 352 00:20:25,332 --> 00:20:27,194 Yes, that was one of the reasons. 353 00:20:27,362 --> 00:20:28,822 And again, if you're still having an 354 00:20:28,836 --> 00:20:30,646 issue, I'm was here to help. 355 00:20:30,708 --> 00:20:33,180 I'm always here to add more content 356 00:20:33,750 --> 00:20:35,868 to newer things that come in. 357 00:20:35,868 --> 00:20:37,654 [No audio]