1 00:00:00,290 --> 00:00:07,790 When we were exploring the system in previous lectures, we may have encountered a problem when trying 2 00:00:07,790 --> 00:00:13,790 to examine a file, for example, such as the shadow files, for example. 3 00:00:13,790 --> 00:00:14,540 File. 4 00:00:15,310 --> 00:00:17,770 And e.t.c. shadow. 5 00:00:17,980 --> 00:00:23,380 And here, as you can see, regular file, no read permission and you can also here less. 6 00:00:23,410 --> 00:00:26,590 We can also here shadow. 7 00:00:26,590 --> 00:00:29,640 And as you can see here, the permission is denied. 8 00:00:29,650 --> 00:00:35,710 So the reason for this error message is that as a regular users, we do not have permissions to read 9 00:00:35,710 --> 00:00:36,400 this file. 10 00:00:36,400 --> 00:00:42,010 In the Unix security model, a user may own files and directories. 11 00:00:42,010 --> 00:00:49,270 So when a user owns a file or directory, the user has control over its access. 12 00:00:49,270 --> 00:00:57,940 User can in turn belong to a group consisting of one or more users who are given access to files and 13 00:00:57,940 --> 00:01:00,190 directories by their owners. 14 00:01:00,190 --> 00:01:07,840 In addition to granting access to a group, an owner may also grant some set of access rights to everybody. 15 00:01:07,840 --> 00:01:17,270 So when in which in Unix terms is referred as the world, so the find out information about your identity, 16 00:01:17,300 --> 00:01:19,370 you can use the ID command. 17 00:01:19,370 --> 00:01:26,450 And as you can see here in this case, in the output when user accounts are created, users are assigned 18 00:01:26,450 --> 00:01:35,270 a number called ID, which is then for the sake of the humans mapped to as a username. 19 00:01:35,270 --> 00:01:41,840 So the user assigned a group ID here GID and may belong to additional groups. 20 00:01:41,840 --> 00:01:51,710 So this example is from our Kali system on other systems such as Fedora or Ubuntu, the output may look 21 00:01:51,710 --> 00:01:55,550 different, so as we can see the user id. 22 00:01:56,560 --> 00:01:58,540 And group the guide here. 23 00:01:58,540 --> 00:02:01,000 Actually, let me write that down here. 24 00:02:01,000 --> 00:02:01,900 So. 25 00:02:02,860 --> 00:02:05,080 Some of you can also understand. 26 00:02:05,080 --> 00:02:10,690 So user ID means user. 27 00:02:11,460 --> 00:02:13,560 UID means user. 28 00:02:14,800 --> 00:02:17,290 Idea and g. 29 00:02:17,330 --> 00:02:19,210 ID g. 30 00:02:21,840 --> 00:02:25,100 Eid Means Group ID. 31 00:02:31,400 --> 00:02:32,780 Here some. 32 00:02:35,130 --> 00:02:40,710 As you can see here, um, in your system, it might be different. 33 00:02:40,710 --> 00:02:44,700 For example, in your system, it might be the 500 or different numbers. 34 00:02:44,700 --> 00:02:47,610 So this is simply because. 35 00:02:49,090 --> 00:02:49,540 In. 36 00:02:49,540 --> 00:02:55,450 If you have if you are getting different numbers in Fedora, Fedora starts its numbering of regular 37 00:02:55,450 --> 00:02:58,730 user accounts from 500. 38 00:02:58,750 --> 00:03:04,780 So in fedora it starts from 500 while the Ubuntu and debian based system. 39 00:03:04,780 --> 00:03:07,240 In this case kali linux is debian based. 40 00:03:07,240 --> 00:03:09,940 It started from 1000. 41 00:03:09,940 --> 00:03:17,320 So we can also see that the Kali Linux user belongs to a lot more groups and this has to do with the 42 00:03:17,320 --> 00:03:25,750 way Ubuntu or Debian or Kali Linux manages privileges for system and devices. 43 00:03:25,750 --> 00:03:28,480 So where does this information come from? 44 00:03:28,480 --> 00:03:33,970 So like so many things in Linux it comes from a couple of text files. 45 00:03:33,970 --> 00:03:37,390 So user accounts are defined in ETSI. 46 00:03:37,630 --> 00:03:38,350 Passe. 47 00:03:38,350 --> 00:03:38,820 W. 48 00:03:38,860 --> 00:03:42,610 Actually, let me write that down here so you can use so. 49 00:03:44,800 --> 00:03:46,010 E of sexual. 50 00:03:46,360 --> 00:03:46,990 Right. 51 00:03:46,990 --> 00:03:55,270 Clear e, t, C and p a s. 52 00:03:57,440 --> 00:03:58,580 S w. 53 00:03:59,540 --> 00:04:14,720 So all of these actions are defined in the Tcpa SSW file and the groups are defined in e t, c, obviously 54 00:04:14,760 --> 00:04:17,210 group file group. 55 00:04:23,020 --> 00:04:31,930 So when a user or user accounts and groups are created, these files are modified. 56 00:04:31,960 --> 00:04:36,250 These files are modified along with the Etsy shadow. 57 00:04:36,640 --> 00:04:39,100 So which and actually Etsy. 58 00:04:39,100 --> 00:04:39,820 Shadow. 59 00:04:39,850 --> 00:04:42,040 Etsy. 60 00:04:42,070 --> 00:04:43,120 Shadow. 61 00:04:46,970 --> 00:04:49,130 It is a shadow file. 62 00:04:51,360 --> 00:04:54,340 Uh, he holds the information about the user password. 63 00:04:54,360 --> 00:05:01,440 So for each user account, for example, ATC password files defines user login. 64 00:05:01,440 --> 00:05:04,320 Name login login. 65 00:05:05,240 --> 00:05:06,140 Name. 66 00:05:07,820 --> 00:05:10,310 User ID, for example, in this case. 67 00:05:10,310 --> 00:05:18,500 And as you can see, user ID, group ID account, real name, home directory, the login shell and, 68 00:05:18,500 --> 00:05:19,850 and so on. 69 00:05:19,850 --> 00:05:31,830 So if we examine the contents of Etsy passed w file that the user login name or actually it is passed 70 00:05:31,850 --> 00:05:35,090 W and actually it is passed. 71 00:05:36,810 --> 00:05:40,020 W d w here. 72 00:05:40,020 --> 00:05:40,740 So. 73 00:05:41,340 --> 00:05:42,390 Here. 74 00:05:44,880 --> 00:05:46,200 If we examine this. 75 00:05:48,350 --> 00:05:51,610 And the Etsy and Etsy Group. 76 00:05:51,620 --> 00:05:56,930 We noticed that besides the regular user accounts, there are accounts for each super user. 77 00:05:56,930 --> 00:06:04,730 In this case a super user accounts here, user ID is zero, super user accounts has zero super ID and 78 00:06:04,730 --> 00:06:06,770 various other system users. 79 00:06:06,770 --> 00:06:12,050 So in next lecture you will learn about the reading, writing and executing in Linux. 80 00:06:12,050 --> 00:06:13,520 So I'm waiting you in next lecture.