WEBVTT 00:00.290 --> 00:07.790 When we were exploring the system in previous lectures, we may have encountered a problem when trying 00:07.790 --> 00:13.790 to examine a file, for example, such as the shadow files, for example. 00:13.790 --> 00:14.540 File. 00:15.310 --> 00:17.770 And e.t.c. shadow. 00:17.980 --> 00:23.380 And here, as you can see, regular file, no read permission and you can also here less. 00:23.410 --> 00:26.590 We can also here shadow. 00:26.590 --> 00:29.640 And as you can see here, the permission is denied. 00:29.650 --> 00:35.710 So the reason for this error message is that as a regular users, we do not have permissions to read 00:35.710 --> 00:36.400 this file. 00:36.400 --> 00:42.010 In the Unix security model, a user may own files and directories. 00:42.010 --> 00:49.270 So when a user owns a file or directory, the user has control over its access. 00:49.270 --> 00:57.940 User can in turn belong to a group consisting of one or more users who are given access to files and 00:57.940 --> 01:00.190 directories by their owners. 01:00.190 --> 01:07.840 In addition to granting access to a group, an owner may also grant some set of access rights to everybody. 01:07.840 --> 01:17.270 So when in which in Unix terms is referred as the world, so the find out information about your identity, 01:17.300 --> 01:19.370 you can use the ID command. 01:19.370 --> 01:26.450 And as you can see here in this case, in the output when user accounts are created, users are assigned 01:26.450 --> 01:35.270 a number called ID, which is then for the sake of the humans mapped to as a username. 01:35.270 --> 01:41.840 So the user assigned a group ID here GID and may belong to additional groups. 01:41.840 --> 01:51.710 So this example is from our Kali system on other systems such as Fedora or Ubuntu, the output may look 01:51.710 --> 01:55.550 different, so as we can see the user id. 01:56.560 --> 01:58.540 And group the guide here. 01:58.540 --> 02:01.000 Actually, let me write that down here. 02:01.000 --> 02:01.900 So. 02:02.860 --> 02:05.080 Some of you can also understand. 02:05.080 --> 02:10.690 So user ID means user. 02:11.460 --> 02:13.560 UID means user. 02:14.800 --> 02:17.290 Idea and g. 02:17.330 --> 02:19.210 ID g. 02:21.840 --> 02:25.100 Eid Means Group ID. 02:31.400 --> 02:32.780 Here some. 02:35.130 --> 02:40.710 As you can see here, um, in your system, it might be different. 02:40.710 --> 02:44.700 For example, in your system, it might be the 500 or different numbers. 02:44.700 --> 02:47.610 So this is simply because. 02:49.090 --> 02:49.540 In. 02:49.540 --> 02:55.450 If you have if you are getting different numbers in Fedora, Fedora starts its numbering of regular 02:55.450 --> 02:58.730 user accounts from 500. 02:58.750 --> 03:04.780 So in fedora it starts from 500 while the Ubuntu and debian based system. 03:04.780 --> 03:07.240 In this case kali linux is debian based. 03:07.240 --> 03:09.940 It started from 1000. 03:09.940 --> 03:17.320 So we can also see that the Kali Linux user belongs to a lot more groups and this has to do with the 03:17.320 --> 03:25.750 way Ubuntu or Debian or Kali Linux manages privileges for system and devices. 03:25.750 --> 03:28.480 So where does this information come from? 03:28.480 --> 03:33.970 So like so many things in Linux it comes from a couple of text files. 03:33.970 --> 03:37.390 So user accounts are defined in ETSI. 03:37.630 --> 03:38.350 Passe. 03:38.350 --> 03:38.820 W. 03:38.860 --> 03:42.610 Actually, let me write that down here so you can use so. 03:44.800 --> 03:46.010 E of sexual. 03:46.360 --> 03:46.990 Right. 03:46.990 --> 03:55.270 Clear e, t, C and p a s. 03:57.440 --> 03:58.580 S w. 03:59.540 --> 04:14.720 So all of these actions are defined in the Tcpa SSW file and the groups are defined in e t, c, obviously 04:14.760 --> 04:17.210 group file group. 04:23.020 --> 04:31.930 So when a user or user accounts and groups are created, these files are modified. 04:31.960 --> 04:36.250 These files are modified along with the Etsy shadow. 04:36.640 --> 04:39.100 So which and actually Etsy. 04:39.100 --> 04:39.820 Shadow. 04:39.850 --> 04:42.040 Etsy. 04:42.070 --> 04:43.120 Shadow. 04:46.970 --> 04:49.130 It is a shadow file. 04:51.360 --> 04:54.340 Uh, he holds the information about the user password. 04:54.360 --> 05:01.440 So for each user account, for example, ATC password files defines user login. 05:01.440 --> 05:04.320 Name login login. 05:05.240 --> 05:06.140 Name. 05:07.820 --> 05:10.310 User ID, for example, in this case. 05:10.310 --> 05:18.500 And as you can see, user ID, group ID account, real name, home directory, the login shell and, 05:18.500 --> 05:19.850 and so on. 05:19.850 --> 05:31.830 So if we examine the contents of Etsy passed w file that the user login name or actually it is passed 05:31.850 --> 05:35.090 W and actually it is passed. 05:36.810 --> 05:40.020 W d w here. 05:40.020 --> 05:40.740 So. 05:41.340 --> 05:42.390 Here. 05:44.880 --> 05:46.200 If we examine this. 05:48.350 --> 05:51.610 And the Etsy and Etsy Group. 05:51.620 --> 05:56.930 We noticed that besides the regular user accounts, there are accounts for each super user. 05:56.930 --> 06:04.730 In this case a super user accounts here, user ID is zero, super user accounts has zero super ID and 06:04.730 --> 06:06.770 various other system users. 06:06.770 --> 06:12.050 So in next lecture you will learn about the reading, writing and executing in Linux. 06:12.050 --> 06:13.520 So I'm waiting you in next lecture.