WEBVTT 1 00:00.000 --> 00:04.040 So friends before we actually kick off this skill, what I want to do is to take 2 00:04.040 --> 00:04.880 a brief moment 3 00:04.880 --> 00:09.890 to discuss with you AC Linux basics. Now at its core what AC Linux is is a 4 00:09.890 --> 00:11.840 mandatory access control 5 00:11.840 --> 00:16.680 that is designed to protect your computer. So the general behaviour of AC Linux 6 00:16.680 --> 00:17.280 is that unless 7 00:17.280 --> 00:21.950 you happen to explicitly permit a connection, then what is going to happen as 8 00:21.950 --> 00:23.200 well, that connection 9 00:23.200 --> 00:27.040 is going to be blocked. Now pretty much with respect to AC Linux, you have this 10 00:27.040 --> 00:28.320 concept of a source 11 00:28.320 --> 00:32.930 object as well as a target object. Now the use of the term object may be a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 11 00:28.320 --> 00:32.930 object as well as a target object. Now the use of the term object may be a 12 00:32.930 --> 00:34.320 little bit confusing, 13 00:34.320 --> 00:39.820 when we refer to a source object, we are talking about users and processes and 14 00:39.820 --> 00:40.320 when we're talking 15 00:40.320 --> 00:44.920 about a target object, we're talking about files, directories or ports. So say 16 00:44.920 --> 00:46.080 for example a user 17 00:46.080 --> 00:50.390 wants to access a particular file on the system, then this can be allowed or 18 00:50.390 --> 00:52.240 disallowed via AC Linux 19 00:52.240 --> 00:56.100 depending on what is known as the security context which is ultimately 20 00:56.100 --> 00:57.920 implemented via the use of 21 00:57.920 --> 01:02.060 labels. So for example this would be as if I go to one of my devices, I can see WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 21 00:57.920 --> 01:02.060 labels. So for example this would be as if I go to one of my devices, I can see 22 01:02.060 --> 01:03.200 I am the nugget user 23 01:03.200 --> 01:07.490 if I do a cd to my home directory and a pwd, if I now list the contents of this 24 01:07.490 --> 01:08.320 directory, we 25 01:08.320 --> 01:12.940 can see all the files and directory within my home directory. Now if I do an ls 26 01:12.940 --> 01:13.600 -z and that is a 27 01:13.600 --> 01:17.640 capital Z and to enter, what we're actually seeing here is the associated 28 01:17.640 --> 01:18.960 security context with 29 01:18.960 --> 01:21.720 these files and directories. Now we're not going to go into too much detail 30 01:21.720 --> 01:22.560 about what all these 31 01:22.560 --> 01:26.310 tags happen to mean, but as a brief refresher if we look at the security 32 01:26.310 --> 01:27.600 context associated with 33 01:27.600 --> 01:31.390 the desktop directory, here's what we have right here. Now basically this is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 33 01:27.600 --> 01:31.390 the desktop directory, here's what we have right here. Now basically this is 34 01:31.390 --> 01:32.640 broken into four different 35 01:32.640 --> 01:37.020 sections and each one is separated via colons, here is the first section or the 36 01:37.020 --> 01:38.000 first tag, then we 37 01:38.000 --> 01:43.000 have the next tag and then the third tag and then the fourth. Now with respect 38 01:43.000 --> 01:44.480 to basic se Linux 39 01:44.480 --> 01:48.400 policy, we are really just concerned about this third tag here, the type tag 40 01:48.400 --> 01:49.520 and pretty much if 41 01:49.520 --> 01:54.640 we want to have a source object, be able to access a target object, effectively 42 01:54.640 --> 01:55.760 they must be able to 43 01:55.760 --> 01:59.860 communicate via the use of these tags. So say for example, if you want to 44 01:59.860 --> 02:01.280 access a particular file WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 44 01:59.860 --> 02:01.280 access a particular file 45 02:01.280 --> 02:05.300 or directory in this home directory, then you would have to have the associated 46 02:05.300 --> 02:07.200 tag user home t and 47 02:07.200 --> 02:10.160 we have a whole bunch of these tags for a whole bunch of different 48 02:10.160 --> 02:11.760 configurations, tags for web 49 02:11.760 --> 02:15.630 services, tags for SSH, that type of thing. Now crucially one thing to note is 50 02:15.630 --> 02:16.800 that these tags can 51 02:16.800 --> 02:20.840 be inherited from parents, but the cool thing is is that they can also be 52 02:20.840 --> 02:22.720 modified and changed and 53 02:22.720 --> 02:27.410 by changing these tags, we can actually grant access from particular processes 54 02:27.410 --> 02:28.480 and users 55 02:28.480 --> 02:33.210 to these targeted files, directories and ports. So with that brief recap out of WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 55 02:28.480 --> 02:33.210 to these targeted files, directories and ports. So with that brief recap out of 56 02:33.210 --> 02:34.160 the way, let's 57 02:34.160 --> 02:38.400 now take a look at modifying label configurations and see how these changes 58 02:38.400 --> 02:39.600 affect the behavior 59 02:39.600 --> 02:40.640 over system.