WEBVTT 00:02.270 --> 00:06.310 In this lecture, you will manipulate the domain name system the and. 00:07.430 --> 00:15.770 Hackers can find a treasure trove of information on a target in its domain name system DNS, so DNS 00:15.770 --> 00:18.350 is a critical component of the internet. 00:18.680 --> 00:27.740 So and although it's designed to translate domain names to IP addresses so A. can use it to garner information 00:27.740 --> 00:28.430 on the target. 00:30.310 --> 00:36.910 And Dennis is a service that translates a domain name like, for example. 00:38.710 --> 00:46.750 Let's open their browser, and they will, for example, Google that come to appropriate IP address. 00:48.510 --> 00:56.670 So I will show you an installation of the end this year will come here. 00:58.110 --> 01:04.320 Actually, our internet is disconnected because I log out our. 01:06.380 --> 01:10.070 Network adapter here, and I will fix it now here. 01:11.850 --> 01:14.210 Let's see if I see a doctor go. 01:14.670 --> 01:15.510 Uh, we will. 01:16.560 --> 01:23.130 Conduct a core here, and I will search here the in this, uh. 01:23.430 --> 01:27.630 And I want to show you an illustration here for better understanding. 01:28.660 --> 01:31.150 Uh, so actually. 01:32.180 --> 01:32.840 In this. 01:35.030 --> 01:35.530 War. 01:42.200 --> 01:47.480 Here, as you can see here, the uh, let me open here. 01:48.540 --> 01:54.330 So, um, this is them our possible attacks here. 01:55.560 --> 02:01.290 So first, I want to talk about, uh uh, is, uh, Google here, for example. 02:02.070 --> 02:09.870 Um, it DNS is a service that translates a domain name, uh, for example, like, uh, Google dot com 02:10.500 --> 02:12.180 to IP address. 02:13.250 --> 02:20.780 So the way your system knows how to get to do it, so without Dennis, we will all have to remember 02:20.780 --> 02:24.290 thousands of IP addresses like that. 02:24.290 --> 02:29.960 For example, in Google, it might be Google Dot com, for example. 02:29.960 --> 02:44.450 It might be one hundred sixty two point eight five eight two here and one hundred thirty two, for example. 02:44.630 --> 02:46.790 So we talked in this. 02:46.790 --> 02:54.260 You have to remember all of these IP addresses without is, uh, logically of the alphabet. 02:54.260 --> 02:59.120 The numbers ordinance converts your domain name to IP address. 02:59.780 --> 03:02.840 So and. 03:05.800 --> 03:10.260 One of the most useful commands for the aspiring hacker is a thick. 03:11.080 --> 03:16.150 Which offers a way to gather DNS information about the target domain. 03:16.630 --> 03:23.320 So the sturdiness information can be a key piece of eerie reconnaissance to obtain before attacking. 03:23.990 --> 03:30.760 So this information called include the IP address of the targets, name servers or the server that translates 03:31.360 --> 03:38.170 to Target's name to an IP address, so the target's email server and potential and its subdomains and 03:38.170 --> 03:38.950 IP addresses. 03:39.370 --> 03:45.430 For instance, let's open our terminal here and enter the big league. 03:46.120 --> 03:55.210 For example, Google Dot Com, you know, as you can see here and we got information from Google here, 03:55.210 --> 03:56.620 as you can see here. 03:59.570 --> 03:59.960 So. 04:03.310 --> 04:09.360 Here and also, as you can see here, we have additional section here. 04:10.150 --> 04:12.910 Degree was the IP address here. 04:14.610 --> 04:20.910 Um, IP address of the DNS server for surfing and Google dot com. 04:21.120 --> 04:28.950 So you can also use that the command to get information on email servers connected to a domain by adding 04:28.950 --> 04:30.480 an X option. 04:30.780 --> 04:35.460 So Amex makes the net short for mail exchange server. 04:35.460 --> 04:40.020 As you can see here, we get so much information about that and for section here. 04:40.350 --> 04:43.110 This is the Google's IP addresses, for example. 04:43.110 --> 04:46.410 Let's get a mix here, right? 04:46.420 --> 04:51.150 A mix here, and we will get, uh, these information here. 04:51.780 --> 04:52.680 So what is this? 04:54.570 --> 05:00.660 This is the information is critical for attacks on and on e-mail systems. 05:00.930 --> 05:09.090 So, for example, info on the Google dot com email servers is shown in the authority sections here. 05:12.660 --> 05:14.070 As you can see here. 05:16.260 --> 05:26.280 Uh, so the most common Linux in a server is the, uh, purple, the internet's named domain b b in 05:26.280 --> 05:26.670 the. 05:27.000 --> 05:37.470 So in some cases, Linux users will refer DNS as B and D, but don't get, uh, B converts or the innocent 05:37.470 --> 05:42.720 B on the be able to map individual domain names to IP addresses. 05:43.690 --> 05:52.320 Uh, we can change our DNS um, server as well, though in some cases you may want to use another adding 05:52.320 --> 05:52.950 a server. 05:53.370 --> 05:56.830 So to do so, you will edit the plain text file names. 05:56.910 --> 05:57.660 Uh, here. 05:57.700 --> 06:04.410 Uh, cut it c uh, restore that Conficker. 06:05.130 --> 06:07.940 Conficker, as you can see here, this is out. 06:07.950 --> 06:10.260 Uh, this is just a small file. 06:10.260 --> 06:18.560 As you can see here we read, uh, it with can't month cut program, so let's open it with leave at 06:18.750 --> 06:19.830 the path. 06:19.950 --> 06:28.260 Actually, it's not mousepad right, must, but it is here so that can here. 06:29.780 --> 06:34.940 So here you will see, and as you can see here, there is a four. 06:35.540 --> 06:44.570 So this is the read, as you can see here for for writing we we have to use sudo command into your college 06:44.640 --> 06:45.170 password. 06:45.500 --> 06:48.260 And as you can see here, this is the variety bill now. 06:48.980 --> 06:58.280 So because of in which our current user, we cannot edit system files, but I used pseudo here. 06:59.510 --> 07:08.600 So now when from the uh, resolv.conf configuration file, the ATC directory directory in my specified 07:08.600 --> 07:12.980 graphical to text editor is, um, musketeer. 07:13.310 --> 07:23.480 So as you can see on Line three here, uh, my name server is set to, uh, a local DNS server, um 07:24.410 --> 07:33.170 uh, one hundred ninety two point one hundred eight, uh, six to eight point fifty eight point two. 07:35.230 --> 07:35.860 And. 07:38.930 --> 07:40.520 And that works fine. 07:41.210 --> 07:49.340 But this, as you can see here, we can use we can use our tool means, for example, if I want to go 07:49.340 --> 07:50.230 to Facebook. 07:50.900 --> 07:52.220 Facebook dot com. 07:52.580 --> 07:54.410 It works, uh, here. 07:55.400 --> 08:01.790 Or if I want to go to Wikipedia here, uh, it works here too, as you can see here. 08:02.450 --> 08:12.950 But if I want to change my DNS server, uh, we we can either replace it with this inside this file 08:12.950 --> 08:13.250 here. 08:13.280 --> 08:22.580 So Google's public DNS server is 8.8.8.8, so I will add the this DNS here. 08:22.580 --> 08:31.910 But first, I want to show you here, uh, Google actually Dr. here. 08:32.910 --> 08:38.400 And go, and this year, I will add Google DNS to my. 08:40.370 --> 08:41.780 Uh, file here. 08:42.620 --> 08:44.690 Google the and as. 08:47.480 --> 08:53.140 Here, and I want to show you what is building this. 08:54.110 --> 08:55.460 As you can see here. 08:58.860 --> 09:00.900 8.8.8.8 here. 09:04.860 --> 09:14.040 As you can see, this is a global city and as, uh, so we we can use Cloudflare seeing this as well 09:14.040 --> 09:14.430 here. 09:15.270 --> 09:22.650 But in this case, I will use the Wall DNS, as you can see here, there's so much being said or see 09:22.650 --> 09:22.800 it. 09:23.400 --> 09:26.940 Quote for DNS is one point one point one point one. 09:27.810 --> 09:31.530 But Google is eight point eight point eight point eight. 09:32.010 --> 09:33.690 So let's change. 09:35.170 --> 09:41.470 Uh, these two 8.8.8.8 here. 09:41.830 --> 09:47.080 And uh, I will add this line to here and. 09:49.180 --> 09:50.850 Just save the file. 09:52.340 --> 10:00.500 So how you can also achieve the same result in exclusively from the common line by entering air. 10:02.380 --> 10:07.920 And call here, name, sir. 10:10.270 --> 10:12.410 8.8.8.8. 10:13.630 --> 10:14.380 And. 10:17.720 --> 10:20.410 Show your cell phone. 10:20.600 --> 10:21.000 Yeah. 10:21.650 --> 10:26.750 Uh, it's uh, we will use pseudo rights because we cannot override. 10:28.620 --> 10:30.400 And if I see her so I want. 10:31.220 --> 10:35.770 Uh, let's check our minds, but as you can see here, we changed it. 10:36.670 --> 10:37.090 So. 10:45.100 --> 10:47.050 If you open them. 10:48.330 --> 10:56.280 It is a resolve configuration file now you shall see that it points DNS requests to Google DNS server 10:56.280 --> 10:59.970 rather than your local DNS server to resolve. 11:01.440 --> 11:09.240 Your system will now go out to the Google public DNS server to resolve domain names to IP addresses. 11:09.780 --> 11:17.100 This can mean domain names take a little longer to resolve problems in milliseconds and therefore to 11:17.100 --> 11:21.690 maintain speed, but to keep the option of using the public server. 11:22.290 --> 11:28.440 You might want to retrain the local DNS server in the install configuration file and follow it with 11:28.440 --> 11:28.600 them. 11:29.010 --> 11:38.930 Public DNS server the operating system and queries each DNS server list and listed in order to order 11:38.940 --> 11:48.150 it appears in its resolve and configuration file, so the system will only refer to the public DNS server 11:48.150 --> 11:52.290 if the domain name can't form in the local DNS server.