1 00:00:00,090 --> 00:00:00,960 In this lesson, 2 00:00:00,960 --> 00:00:03,423 we're going to cover the Debian packages and APT. 3 00:00:04,290 --> 00:00:07,050 Debian is one of the most prominent Linux distributions 4 00:00:07,050 --> 00:00:09,240 and it has its own package manager. 5 00:00:09,240 --> 00:00:11,100 There are various programs that Debian has 6 00:00:11,100 --> 00:00:12,540 for managing its packages. 7 00:00:12,540 --> 00:00:16,620 However, we're going to focus mainly on DPKG and APT 8 00:00:16,620 --> 00:00:17,850 since there are multiple tools 9 00:00:17,850 --> 00:00:19,710 that are used to manage Debian packages 10 00:00:19,710 --> 00:00:21,750 from graphic and text based interfaces 11 00:00:21,750 --> 00:00:24,240 to low level tools that are used to install packages. 12 00:00:24,240 --> 00:00:28,440 But as I said, our focus is going to be on DPKG and APT 13 00:00:28,440 --> 00:00:31,650 'cause those are clearly listed out in your exam objectives. 14 00:00:31,650 --> 00:00:33,240 Now the main package management program 15 00:00:33,240 --> 00:00:36,180 that Debian uses is DPKG. 16 00:00:36,180 --> 00:00:41,180 The DPKG command does use .deb files as its packages. 17 00:00:41,730 --> 00:00:44,520 DPKG is the command that's used to manage packages 18 00:00:44,520 --> 00:00:47,700 on Debian derived distributions, including Kali Linux 19 00:00:47,700 --> 00:00:50,130 that you'll use as a penetration tester. 20 00:00:50,130 --> 00:00:51,990 It includes lots of different options 21 00:00:51,990 --> 00:00:54,570 including -i and the package name 22 00:00:54,570 --> 00:00:56,910 which is used to install the package, 23 00:00:56,910 --> 00:00:59,310 r and the package name, which is used to remove 24 00:00:59,310 --> 00:01:01,290 or uninstall the package, 25 00:01:01,290 --> 00:01:02,670 l and the package name 26 00:01:02,670 --> 00:01:04,050 which is used to list information 27 00:01:04,050 --> 00:01:05,910 about the specified package. 28 00:01:05,910 --> 00:01:07,590 If you don't provide a package name, 29 00:01:07,590 --> 00:01:08,423 it's going to go ahead 30 00:01:08,423 --> 00:01:10,440 and list all of your installed packages. 31 00:01:10,440 --> 00:01:12,750 And then -s and the package name, 32 00:01:12,750 --> 00:01:13,800 which is used to report about 33 00:01:13,800 --> 00:01:16,110 whether a package is actually installed or not. 34 00:01:16,110 --> 00:01:17,670 For example, you might go 35 00:01:17,670 --> 00:01:20,100 is an Apache web server installed on the system? 36 00:01:20,100 --> 00:01:24,750 And you could type in dpkg -s apache2 and hit enter, 37 00:01:24,750 --> 00:01:26,040 and then find out whether or not 38 00:01:26,040 --> 00:01:27,990 Apache2 is already installed. 39 00:01:27,990 --> 00:01:29,700 To run the DPKG command, 40 00:01:29,700 --> 00:01:34,200 simply type in dpkg, the options and the package name. 41 00:01:34,200 --> 00:01:37,080 Now you may be wondering when you use DPKG 42 00:01:37,080 --> 00:01:39,600 and you install a component, does it also ensure 43 00:01:39,600 --> 00:01:41,520 all the necessary components are installed? 44 00:01:41,520 --> 00:01:43,080 And the answer is yes. 45 00:01:43,080 --> 00:01:45,450 It's one of the great things about DPKG 46 00:01:45,450 --> 00:01:47,460 is that it's going to go and find all the dependencies 47 00:01:47,460 --> 00:01:48,870 and install those for you 48 00:01:48,870 --> 00:01:52,710 when you're using DPKG with the -i option. 49 00:01:52,710 --> 00:01:55,020 Now, in addition to using DPKG, 50 00:01:55,020 --> 00:01:58,530 you can also use a newer version known as APT. 51 00:01:58,530 --> 00:02:01,230 Remember, DPKG was the original installer 52 00:02:01,230 --> 00:02:03,450 for Debian based Linux distributions 53 00:02:03,450 --> 00:02:07,260 but APT, instead is going to be a front end manager 54 00:02:07,260 --> 00:02:09,690 for that DPKG system. 55 00:02:09,690 --> 00:02:12,750 And much like yum is a front end manager for RPM 56 00:02:12,750 --> 00:02:14,820 inside of our Red Hat based distributions, 57 00:02:14,820 --> 00:02:18,780 we're going to use APT as a front end manager for DPKG 58 00:02:18,780 --> 00:02:20,790 on our Debian based systems. 59 00:02:20,790 --> 00:02:24,330 For a long time, APT actually used its commands 60 00:02:24,330 --> 00:02:26,250 by using a hyphenated scheme. 61 00:02:26,250 --> 00:02:29,100 So you might do things like apt-get 62 00:02:29,100 --> 00:02:32,910 or apt-cache to be able to interact with that system. 63 00:02:32,910 --> 00:02:35,130 Now there's a lot of different sub commands 64 00:02:35,130 --> 00:02:37,500 that are now added into APT as well. 65 00:02:37,500 --> 00:02:39,240 So if you want to install a package, 66 00:02:39,240 --> 00:02:42,780 you'll simply type apt install and the package name. 67 00:02:42,780 --> 00:02:44,880 This will install your packages. 68 00:02:44,880 --> 00:02:46,500 If you want to remove a package, 69 00:02:46,500 --> 00:02:49,920 you can then use apt remove and the package name 70 00:02:49,920 --> 00:02:51,660 to uninstall that package. 71 00:02:51,660 --> 00:02:54,150 Now, when you remove a package using APT, 72 00:02:54,150 --> 00:02:56,850 it does leave behind its configuration files. 73 00:02:56,850 --> 00:02:58,080 So this is important to know 74 00:02:58,080 --> 00:03:00,480 because if you go and reinstall that package later, 75 00:03:00,480 --> 00:03:03,660 a lot of those configurations will still be there for you. 76 00:03:03,660 --> 00:03:06,510 Another sub command we have is the purge sub command. 77 00:03:06,510 --> 00:03:10,200 You use this by typing apt purge and the package name 78 00:03:10,200 --> 00:03:11,370 to uninstall the package 79 00:03:11,370 --> 00:03:13,860 and remove its configuration files. 80 00:03:13,860 --> 00:03:15,990 If you want to get information about a package, 81 00:03:15,990 --> 00:03:19,050 you can type in apt show and the package name 82 00:03:19,050 --> 00:03:21,600 to report information about that package. 83 00:03:21,600 --> 00:03:23,280 If you want to know what version information 84 00:03:23,280 --> 00:03:24,990 you have on a particular package, 85 00:03:24,990 --> 00:03:28,170 you could type in apt version and the package name. 86 00:03:28,170 --> 00:03:31,050 The apt update sub command is one that we're going to use 87 00:03:31,050 --> 00:03:32,880 to update the APT database 88 00:03:32,880 --> 00:03:35,760 of the different available packages that we could install. 89 00:03:35,760 --> 00:03:37,800 And then if we use the upgrade sub command, 90 00:03:37,800 --> 00:03:40,770 we can type in apt upgrade and the package name 91 00:03:40,770 --> 00:03:42,870 to upgrade a particular software package 92 00:03:42,870 --> 00:03:44,400 to the latest version. 93 00:03:44,400 --> 00:03:45,420 If you want to upgrade 94 00:03:45,420 --> 00:03:47,940 all of your software packages to the latest version, 95 00:03:47,940 --> 00:03:51,420 you can do that by typing apt upgrade and hitting enter. 96 00:03:51,420 --> 00:03:53,370 By not specifying a package name, 97 00:03:53,370 --> 00:03:54,930 it tells the system you want to go ahead 98 00:03:54,930 --> 00:03:56,730 and upgrade all of them. 99 00:03:56,730 --> 00:04:00,270 To use APT, simply type in apt, the options, 100 00:04:00,270 --> 00:04:02,160 the sub command and the package name 101 00:04:02,160 --> 00:04:03,480 to be able to run APT 102 00:04:03,480 --> 00:04:05,310 and interact with the different packages 103 00:04:05,310 --> 00:04:07,320 using that package manager. 104 00:04:07,320 --> 00:04:09,480 Now, as I said, there were some other commands 105 00:04:09,480 --> 00:04:13,350 like apt-get, and apt-cache. 106 00:04:13,350 --> 00:04:15,300 These commands are still functional 107 00:04:15,300 --> 00:04:17,490 but they provide a lower level functionality 108 00:04:17,490 --> 00:04:19,769 and have more tight, specific controls 109 00:04:19,769 --> 00:04:23,820 than using the generic apt command with its sub commands. 110 00:04:23,820 --> 00:04:25,980 Now, these become a little bit more confusing 111 00:04:25,980 --> 00:04:28,560 because there's a lot of different options that you can do 112 00:04:28,560 --> 00:04:32,220 by using the apt get or apt cache command. 113 00:04:32,220 --> 00:04:34,230 Because of this, most people now rely 114 00:04:34,230 --> 00:04:36,750 on the newer variants of apt install 115 00:04:36,750 --> 00:04:40,470 or apt remove instead of using apt-get. 116 00:04:40,470 --> 00:04:42,810 The apt-cache is how you interact 117 00:04:42,810 --> 00:04:46,080 with the underlying database of the APT system. 118 00:04:46,080 --> 00:04:48,360 But again, you can do much of the same things 119 00:04:48,360 --> 00:04:50,490 using the other commands I just went through. 120 00:04:50,490 --> 00:04:53,580 For example, if you want to display package information, 121 00:04:53,580 --> 00:04:57,900 you used to be able to use apt-cache show package name, 122 00:04:57,900 --> 00:05:01,770 but now you can just use apt show package name 123 00:05:01,770 --> 00:05:03,690 and it will do the same thing. 124 00:05:03,690 --> 00:05:06,450 Now, the last thing I want to talk about in terms of APT 125 00:05:06,450 --> 00:05:08,700 is the difference between update and upgrade 126 00:05:08,700 --> 00:05:11,280 because a lot of people get this confused. 127 00:05:11,280 --> 00:05:13,530 The apt update command is going to be used 128 00:05:13,530 --> 00:05:17,130 to update the APT database of the available packages. 129 00:05:17,130 --> 00:05:18,990 This enables APT to become aware 130 00:05:18,990 --> 00:05:20,790 of any new versions of software 131 00:05:20,790 --> 00:05:22,680 that may now become available. 132 00:05:22,680 --> 00:05:24,990 For instance, if I ran one of these projects, 133 00:05:24,990 --> 00:05:26,970 I might have version 1.1 out. 134 00:05:26,970 --> 00:05:30,210 When I make a code update and this becomes version 1.2, 135 00:05:30,210 --> 00:05:32,580 I now can tell that to the APT system 136 00:05:32,580 --> 00:05:33,900 through the repositories, 137 00:05:33,900 --> 00:05:37,950 but your system won't know it until you do an APT update 138 00:05:37,950 --> 00:05:39,270 where it queries the database 139 00:05:39,270 --> 00:05:41,820 and says, give me all the latest information. 140 00:05:41,820 --> 00:05:43,110 Now, when we're looking at 141 00:05:43,110 --> 00:05:45,090 the upgrade option on the other hand, 142 00:05:45,090 --> 00:05:48,360 this is actually going to be used to install new software. 143 00:05:48,360 --> 00:05:53,100 Remember, apt update does not upgrade your software. 144 00:05:53,100 --> 00:05:55,200 It doesn't do anything to your own system 145 00:05:55,200 --> 00:05:57,870 except tell you what versions are now available. 146 00:05:57,870 --> 00:06:00,180 When you're using apt upgrade though, 147 00:06:00,180 --> 00:06:02,520 you're actually going and updating that software 148 00:06:02,520 --> 00:06:04,380 to the newer version that you just found 149 00:06:04,380 --> 00:06:06,540 inside the APT database. 150 00:06:06,540 --> 00:06:08,640 This is the full upgrade of the software 151 00:06:08,640 --> 00:06:11,430 and so we can actually download the latest version, 152 00:06:11,430 --> 00:06:12,600 install it on our system 153 00:06:12,600 --> 00:06:14,340 and use the new code and it's features 154 00:06:14,340 --> 00:06:16,080 that it's going to be installing. 155 00:06:16,080 --> 00:06:17,430 This is an important distinction 156 00:06:17,430 --> 00:06:18,480 that you should be aware of 157 00:06:18,480 --> 00:06:21,690 between apt update and apt upgrade. 158 00:06:21,690 --> 00:06:23,910 Now, that being said, as a best practice, 159 00:06:23,910 --> 00:06:26,340 whenever you're going to install a new piece of software, 160 00:06:26,340 --> 00:06:27,480 what should you do? 161 00:06:27,480 --> 00:06:31,110 Well, first, you should run apt update and hit enter. 162 00:06:31,110 --> 00:06:33,240 This will tell you what the latest version is. 163 00:06:33,240 --> 00:06:36,450 Then you should do apt upgrade and the package name 164 00:06:36,450 --> 00:06:38,010 to upgrade your specific package 165 00:06:38,010 --> 00:06:40,440 to that latest version that you just found. 166 00:06:40,440 --> 00:06:43,020 If you don't do the apt update first, 167 00:06:43,020 --> 00:06:45,720 you could be upgrading yourself to an older version 168 00:06:45,720 --> 00:06:47,640 and not the latest version that's available. 169 00:06:47,640 --> 00:06:48,630 So keep that in mind 170 00:06:48,630 --> 00:06:52,440 with differences between apt update and apt upgrade. 171 00:06:52,440 --> 00:06:54,510 And in general, always do an update 172 00:06:54,510 --> 00:06:55,953 before you do an upgrade.