1 00:00:00,020 --> 00:00:00,990 In this lesson, 2 00:00:00,990 --> 00:00:03,330 we're going to discuss various Linux server roles 3 00:00:03,330 --> 00:00:05,370 that you may encounter in the field. 4 00:00:05,370 --> 00:00:06,480 When you're using Linux, 5 00:00:06,480 --> 00:00:08,820 there are a wide variety of network services 6 00:00:08,820 --> 00:00:10,950 that can be configured and run as part of the services 7 00:00:10,950 --> 00:00:12,270 that you're providing. 8 00:00:12,270 --> 00:00:14,850 In this lesson, we're going to cover a wide variety 9 00:00:14,850 --> 00:00:16,710 of the most commonly used services 10 00:00:16,710 --> 00:00:19,470 and a detailed coverage of these individual services 11 00:00:19,470 --> 00:00:21,510 that make up the larger package. 12 00:00:21,510 --> 00:00:23,250 Since there are so many types of servers 13 00:00:23,250 --> 00:00:24,900 that a server can actually be, 14 00:00:24,900 --> 00:00:27,810 Linux just installs the essentials by default. 15 00:00:27,810 --> 00:00:30,450 That way you have plenty of space for any extra packages 16 00:00:30,450 --> 00:00:33,210 or files that you may need to add later on. 17 00:00:33,210 --> 00:00:34,830 During the installation process, 18 00:00:34,830 --> 00:00:36,990 if you choose a common server role though, 19 00:00:36,990 --> 00:00:39,240 Linux will actually install the different packages 20 00:00:39,240 --> 00:00:41,280 you're going to need for that server role. 21 00:00:41,280 --> 00:00:43,590 And this helps to streamline the process. 22 00:00:43,590 --> 00:00:45,570 You can even choose one or more sets 23 00:00:45,570 --> 00:00:47,790 of these different servers or server roles, 24 00:00:47,790 --> 00:00:50,520 and all that software will be installed for you. 25 00:00:50,520 --> 00:00:53,160 For example, I can have a single Linux server 26 00:00:53,160 --> 00:00:55,170 that's serving as a Samba file server, 27 00:00:55,170 --> 00:00:58,140 as well as a DNS server and an SSH server. 28 00:00:58,140 --> 00:01:00,060 If I choose all three of those roles, 29 00:01:00,060 --> 00:01:02,610 Linux will install all three of those sets of packages 30 00:01:02,610 --> 00:01:05,850 and dependencies to ensure I can run those functions. 31 00:01:05,850 --> 00:01:07,350 After you've partitioned and installed 32 00:01:07,350 --> 00:01:08,850 the base operating system, 33 00:01:08,850 --> 00:01:10,920 you can go into your Linux operating system 34 00:01:10,920 --> 00:01:12,720 and choose from a predefined collection 35 00:01:12,720 --> 00:01:14,340 of different software types. 36 00:01:14,340 --> 00:01:17,820 This includes network time servers, secure shell servers, 37 00:01:17,820 --> 00:01:21,000 web servers, PKI, and certificate servers, 38 00:01:21,000 --> 00:01:24,450 name resolution servers, DHCP servers, 39 00:01:24,450 --> 00:01:26,790 Simple Network Management Protocol servers, 40 00:01:26,790 --> 00:01:31,110 centralized authentication, or LDAP servers, proxy servers, 41 00:01:31,110 --> 00:01:34,530 and many others that we're going to talk about in this lesson. 42 00:01:34,530 --> 00:01:37,440 Now let's first talk about NTP. 43 00:01:37,440 --> 00:01:40,320 NTP stands for the Network Time Protocol. 44 00:01:40,320 --> 00:01:42,870 And by default, this is a service or a server 45 00:01:42,870 --> 00:01:45,330 that is not going to be running on a Linux machine. 46 00:01:45,330 --> 00:01:48,270 You have to enable this if you want to be able to operate it. 47 00:01:48,270 --> 00:01:51,240 Now, NTP gives you the ability to synchronize time 48 00:01:51,240 --> 00:01:54,360 across the entire network by having one server 49 00:01:54,360 --> 00:01:57,780 act as the time source for everything else on the network. 50 00:01:57,780 --> 00:02:00,090 If you want your Linux server to be that definitive 51 00:02:00,090 --> 00:02:03,240 time source, you need to run the NTP Damon, 52 00:02:03,240 --> 00:02:07,350 which will install the NTP server on your Linux machine. 53 00:02:07,350 --> 00:02:09,479 Now, in addition to the NTP protocol, 54 00:02:09,479 --> 00:02:12,330 you need software to utilize NTP. 55 00:02:12,330 --> 00:02:14,250 And one of the most common ones used on Linux 56 00:02:14,250 --> 00:02:15,810 is known as Crony. 57 00:02:15,810 --> 00:02:17,970 Crony was designed to perform in a large range 58 00:02:17,970 --> 00:02:20,820 of conditions, including intermittent network connectivity, 59 00:02:20,820 --> 00:02:23,550 heavily congested networks, changing temperatures 60 00:02:23,550 --> 00:02:25,470 where ordinary computer clocks might be able 61 00:02:25,470 --> 00:02:28,290 to lose time based on that, and the ability to run 62 00:02:28,290 --> 00:02:29,700 on a virtual machine. 63 00:02:29,700 --> 00:02:33,330 So if you need a really versatile implementation of NTP, 64 00:02:33,330 --> 00:02:35,850 you can always use Crony and the Crony Damon 65 00:02:35,850 --> 00:02:37,440 to be able to do that. 66 00:02:37,440 --> 00:02:39,750 Second, we have SSH. 67 00:02:39,750 --> 00:02:42,780 Now SSH stands for the Secure Shell Service. 68 00:02:42,780 --> 00:02:44,790 And secure shell is going to provide you 69 00:02:44,790 --> 00:02:46,620 with an authenticated encrypted method 70 00:02:46,620 --> 00:02:50,520 of connecting to a remote or local system over the network. 71 00:02:50,520 --> 00:02:53,070 Now, most frequently, you're going to see SSH used 72 00:02:53,070 --> 00:02:55,200 as a remote administration protocol, 73 00:02:55,200 --> 00:02:57,330 but it can also be used to tunnel 74 00:02:57,330 --> 00:02:59,250 other different types of traffic through it 75 00:02:59,250 --> 00:03:00,720 in a secure manner. 76 00:03:00,720 --> 00:03:03,480 For example, if you want to run FTP, 77 00:03:03,480 --> 00:03:05,850 by default, the traffic is unencrypted. 78 00:03:05,850 --> 00:03:08,190 So if you're logging into an FTP server, 79 00:03:08,190 --> 00:03:09,450 that username and password 80 00:03:09,450 --> 00:03:11,580 can be seen by other people in the network, 81 00:03:11,580 --> 00:03:14,250 but if you actually tunnel the FTP traffic 82 00:03:14,250 --> 00:03:16,170 through an SSH connection, 83 00:03:16,170 --> 00:03:18,420 it's going to become encrypted because SSH 84 00:03:18,420 --> 00:03:20,340 is encrypted by default. 85 00:03:20,340 --> 00:03:24,270 Now by default, Windows does not come with an SSH client. 86 00:03:24,270 --> 00:03:28,050 So even if you set up an SSH server on your Linux machine, 87 00:03:28,050 --> 00:03:30,630 the Windows machine won't know how to connect to it. 88 00:03:30,630 --> 00:03:33,300 If you're using windows as your daily operating system, 89 00:03:33,300 --> 00:03:36,180 and you're trying to connect to a Linux server over SSH, 90 00:03:36,180 --> 00:03:38,970 you're going to have to install a third party tool like PuTTY. 91 00:03:38,970 --> 00:03:41,100 And this will allow you to work from a Window system 92 00:03:41,100 --> 00:03:44,070 and connect over SSH to an SSH server 93 00:03:44,070 --> 00:03:46,020 running on a Linux environment. 94 00:03:46,020 --> 00:03:48,180 And that way, you can connect to a remote server 95 00:03:48,180 --> 00:03:51,180 over the internet and do your configurations. 96 00:03:51,180 --> 00:03:53,550 Next, we're going to talk about web servers. 97 00:03:53,550 --> 00:03:56,520 Now web servers can either be unsecure or secure. 98 00:03:56,520 --> 00:03:59,550 If they're unsecure, you're going to be using HTTP, 99 00:03:59,550 --> 00:04:01,800 which is the Hyper Text Transfer Protocol. 100 00:04:01,800 --> 00:04:05,220 And this operates using TCP over port 80. 101 00:04:05,220 --> 00:04:07,530 If you're using a secure and encrypted version, 102 00:04:07,530 --> 00:04:09,990 this is known as HTTPS, 103 00:04:09,990 --> 00:04:13,050 which stands for Hyper Text Transfer Protocol Secure. 104 00:04:13,050 --> 00:04:17,430 This uses TCP over port 443 to make its connection. 105 00:04:17,430 --> 00:04:19,980 Generally, to run one of these services, 106 00:04:19,980 --> 00:04:24,390 HTTP or HTTPS is just going to be the protocol that's used, 107 00:04:24,390 --> 00:04:25,950 but the server you're going to use 108 00:04:25,950 --> 00:04:27,450 is going to be something else. 109 00:04:27,450 --> 00:04:30,960 Normally, this is something like Apache or Nginx. 110 00:04:30,960 --> 00:04:32,580 When you have this server running, 111 00:04:32,580 --> 00:04:35,580 it's what's hosting all the websites on the internet. 112 00:04:35,580 --> 00:04:37,260 And so if you want to run your own web server 113 00:04:37,260 --> 00:04:40,500 on a Linux machine, you have to install a server Damon 114 00:04:40,500 --> 00:04:42,360 known as Apache or Nginx, 115 00:04:42,360 --> 00:04:44,100 or one of the other ones that are out there 116 00:04:44,100 --> 00:04:47,010 to be able to operate over port 80 or port 443 117 00:04:47,010 --> 00:04:50,070 and deliver those webpages and files and images 118 00:04:50,070 --> 00:04:52,560 over the internet to your users. 119 00:04:52,560 --> 00:04:54,240 The next type of server we're going to talk about 120 00:04:54,240 --> 00:04:55,860 is a certificate server. 121 00:04:55,860 --> 00:04:57,390 Now certificates are used to provide 122 00:04:57,390 --> 00:04:59,640 a way of guaranteeing somebody's identity, 123 00:04:59,640 --> 00:05:02,310 whether that's a user or a server itself. 124 00:05:02,310 --> 00:05:04,890 These certificates are known as digital certificates, 125 00:05:04,890 --> 00:05:06,300 and they're part of the PKI 126 00:05:06,300 --> 00:05:08,400 or Public Key Infrastructure system. 127 00:05:08,400 --> 00:05:11,400 And this uses asymmetric encryption and hashing techniques 128 00:05:11,400 --> 00:05:14,400 to validate that somebody is who they say they are. 129 00:05:14,400 --> 00:05:15,233 To do this though, 130 00:05:15,233 --> 00:05:16,530 you have to have a central server 131 00:05:16,530 --> 00:05:18,390 to manage all of these certificates. 132 00:05:18,390 --> 00:05:22,320 And that is known as a CA or Certificate Authority. 133 00:05:22,320 --> 00:05:25,230 These CAs or certificate authorities are used to manage 134 00:05:25,230 --> 00:05:28,290 the enrollment, approval, expiration, and revocation 135 00:05:28,290 --> 00:05:30,780 of all these different digital certificates. 136 00:05:30,780 --> 00:05:32,730 If you're working for a large organization, 137 00:05:32,730 --> 00:05:34,110 it's very possible that you're running 138 00:05:34,110 --> 00:05:36,270 your own certificate authority to be able to create 139 00:05:36,270 --> 00:05:38,130 digital certificates for all of your users 140 00:05:38,130 --> 00:05:41,040 and all of your machines inside of your network. 141 00:05:41,040 --> 00:05:43,560 Generally, if you're going to be hosting a web server, 142 00:05:43,560 --> 00:05:45,990 you have a digital certificate installed there as well, 143 00:05:45,990 --> 00:05:48,240 but it's not from your own certificate authority. 144 00:05:48,240 --> 00:05:50,910 It's from a third party trusted certificate authority 145 00:05:50,910 --> 00:05:52,980 like Verisign or Entrust, 146 00:05:52,980 --> 00:05:55,590 and that way other people from outside your organization, 147 00:05:55,590 --> 00:05:57,000 when they connect to your web server, 148 00:05:57,000 --> 00:05:58,500 can also trust that server 149 00:05:58,500 --> 00:06:01,620 because that server assigned by that trusted third party. 150 00:06:01,620 --> 00:06:03,240 The next server we're going to talk about 151 00:06:03,240 --> 00:06:07,590 is known as a DNS server or Domain Name System server. 152 00:06:07,590 --> 00:06:10,890 Now a DNS server performs name resolution for us. 153 00:06:10,890 --> 00:06:12,810 And name resolution means that we can use 154 00:06:12,810 --> 00:06:16,380 these easy to remember host names like diontraining.com, 155 00:06:16,380 --> 00:06:19,470 and have that automatically convert into an IP address 156 00:06:19,470 --> 00:06:20,820 for that server. 157 00:06:20,820 --> 00:06:22,230 That way we don't have to remember 158 00:06:22,230 --> 00:06:26,340 a number like 66.123.52.8 159 00:06:26,340 --> 00:06:28,500 every time you want to go to my website. 160 00:06:28,500 --> 00:06:31,350 Instead, you can just type in diontraining.com. 161 00:06:31,350 --> 00:06:33,510 And because we have a DNS server that's up and running, 162 00:06:33,510 --> 00:06:36,030 it will convert those names to IP addresses, 163 00:06:36,030 --> 00:06:38,220 and allow you to know where we are. 164 00:06:38,220 --> 00:06:41,340 A DNS server is going to serve basically as a record holder 165 00:06:41,340 --> 00:06:43,890 for all the company's internal network records 166 00:06:43,890 --> 00:06:45,390 and all of your host names, 167 00:06:45,390 --> 00:06:48,990 or you may have a public facing DNS server like I do. 168 00:06:48,990 --> 00:06:51,120 And in that case, we become part of the larger 169 00:06:51,120 --> 00:06:53,160 internet name resolution infrastructure 170 00:06:53,160 --> 00:06:54,870 so anyone in the world can figure out 171 00:06:54,870 --> 00:06:57,450 where diontraining.com is. 172 00:06:57,450 --> 00:07:00,780 The next one we're going to talk about is a DHCP server. 173 00:07:00,780 --> 00:07:04,920 Now DHCP server stands for Dynamic Host Control Protocol. 174 00:07:04,920 --> 00:07:07,110 When you have a Linux server or workstation, 175 00:07:07,110 --> 00:07:09,537 you have to configure it to participate on the network. 176 00:07:09,537 --> 00:07:12,060 And you can do this either statically or dynamically. 177 00:07:12,060 --> 00:07:13,560 like I said before. 178 00:07:13,560 --> 00:07:15,930 If you're going to use dynamic assignments on your network, 179 00:07:15,930 --> 00:07:18,300 that means you have to have a DHCP server 180 00:07:18,300 --> 00:07:20,760 that's going to be handing out those IP addresses. 181 00:07:20,760 --> 00:07:22,530 When somebody connects to your network, 182 00:07:22,530 --> 00:07:24,540 the DHCP server is going to be responsible 183 00:07:24,540 --> 00:07:27,270 for giving them an IP address, a subnet mask, 184 00:07:27,270 --> 00:07:28,980 the default gateway to your router, 185 00:07:28,980 --> 00:07:32,160 and other values like the location of the DNS server. 186 00:07:32,160 --> 00:07:33,960 By doing all these configurations, 187 00:07:33,960 --> 00:07:37,290 we can do them in this dynamic manner using DHCP. 188 00:07:37,290 --> 00:07:39,120 And this makes it really easy for us, 189 00:07:39,120 --> 00:07:41,790 especially if you have a lot of clients. 190 00:07:41,790 --> 00:07:44,340 For example, in one of my previous organizations, 191 00:07:44,340 --> 00:07:48,270 we had 15,000 end user workstations and laptops. 192 00:07:48,270 --> 00:07:50,550 I didn't want to have to configure all those statically 193 00:07:50,550 --> 00:07:52,830 and assign all four of those pieces of information 194 00:07:52,830 --> 00:07:54,750 to each and every one of those clients. 195 00:07:54,750 --> 00:07:58,110 So instead, we set them all up to use DHCP 196 00:07:58,110 --> 00:08:00,720 and pointed them towards our network's, DHCP server, 197 00:08:00,720 --> 00:08:03,270 which was a Linux machine that handed out that information 198 00:08:03,270 --> 00:08:06,030 to those clients when they connected to the network. 199 00:08:06,030 --> 00:08:09,090 Now some of your network devices can also pass information 200 00:08:09,090 --> 00:08:11,250 about their performance and their workloads 201 00:08:11,250 --> 00:08:13,500 over to a central management database. 202 00:08:13,500 --> 00:08:16,800 To do this, they use something known as SNMP, 203 00:08:16,800 --> 00:08:19,470 or the Simple Network Management Protocol. 204 00:08:19,470 --> 00:08:22,080 SNMP is going to allow us to be able to use 205 00:08:22,080 --> 00:08:24,390 all these different devices across the network, 206 00:08:24,390 --> 00:08:27,150 like routers, switches, servers, and endpoints, 207 00:08:27,150 --> 00:08:28,860 and be able to collect that information 208 00:08:28,860 --> 00:08:30,450 at a centralized server. 209 00:08:30,450 --> 00:08:32,789 That centralized server could be running Linux. 210 00:08:32,789 --> 00:08:35,070 And if you have it configured to act as an SNMP 211 00:08:35,070 --> 00:08:36,750 centralized database server, 212 00:08:36,750 --> 00:08:38,850 it'll go ahead and perform that server role 213 00:08:38,850 --> 00:08:41,340 and collect all the information from all the other devices 214 00:08:41,340 --> 00:08:42,842 and clients on the network. 215 00:08:43,679 --> 00:08:45,300 The next server we're going to talk about 216 00:08:45,300 --> 00:08:47,760 is your centralized authentication server. 217 00:08:47,760 --> 00:08:51,630 And this relies on a protocol known as LDAP, L-D-A-P, 218 00:08:51,630 --> 00:08:54,810 which stands for the Lightweight Directory Access Protocol. 219 00:08:54,810 --> 00:08:56,820 This centralized authentication server 220 00:08:56,820 --> 00:08:58,830 will contain all the user identities 221 00:08:58,830 --> 00:09:00,360 on that centralized server. 222 00:09:00,360 --> 00:09:02,670 So when somebody tries to log into a local workstation 223 00:09:02,670 --> 00:09:05,100 like a Windows, Mac, or Linux machine, 224 00:09:05,100 --> 00:09:07,440 that system is actually going to connect to this centralized 225 00:09:07,440 --> 00:09:11,100 authentication server and verify you are who you say you are 226 00:09:11,100 --> 00:09:12,930 by validating your username and password, 227 00:09:12,930 --> 00:09:15,180 and then letting you log onto the machine. 228 00:09:15,180 --> 00:09:17,820 This makes the network more secure, simpler to manage, 229 00:09:17,820 --> 00:09:20,040 and much easier for users to navigate 230 00:09:20,040 --> 00:09:22,410 because their one account can work on any workstation 231 00:09:22,410 --> 00:09:25,170 across that network instead of only the one computer 232 00:09:25,170 --> 00:09:26,940 they're assigned at their desk. 233 00:09:26,940 --> 00:09:29,520 Authentication servers are used to hold all the information 234 00:09:29,520 --> 00:09:32,370 about the user identities inside of this directory store 235 00:09:32,370 --> 00:09:33,990 known as LDAP. 236 00:09:33,990 --> 00:09:36,450 Now, when a user tries to authenticate to the system, 237 00:09:36,450 --> 00:09:38,550 their username and password are going to be hashed, 238 00:09:38,550 --> 00:09:40,350 sent over to the authentication server, 239 00:09:40,350 --> 00:09:41,550 checked against the database. 240 00:09:41,550 --> 00:09:43,560 And if they're authorized, they'll then be allowed 241 00:09:43,560 --> 00:09:46,080 to log into that local workstation. 242 00:09:46,080 --> 00:09:48,630 Next, we're going to talk about proxy servers. 243 00:09:48,630 --> 00:09:50,850 Now a proxy service resides on a system 244 00:09:50,850 --> 00:09:52,860 that has a direct connection to the internet, 245 00:09:52,860 --> 00:09:54,570 and also has another connection 246 00:09:54,570 --> 00:09:56,550 to the internal network connection. 247 00:09:56,550 --> 00:09:58,440 This way, it acts as a person in the middle 248 00:09:58,440 --> 00:09:59,430 of the connection. 249 00:09:59,430 --> 00:10:01,530 And anytime somebody wants to get out to the internet, 250 00:10:01,530 --> 00:10:03,810 they have to connect to the proxy server first, 251 00:10:03,810 --> 00:10:05,640 the proxy server takes that request, 252 00:10:05,640 --> 00:10:07,050 passes it over to the internet, 253 00:10:07,050 --> 00:10:09,030 gets the information back and then passes it 254 00:10:09,030 --> 00:10:10,530 back to that end user. 255 00:10:10,530 --> 00:10:12,420 Now, why would we want to do this? 256 00:10:12,420 --> 00:10:14,100 Well, the main reason we want to do this 257 00:10:14,100 --> 00:10:15,570 is to be able to log any requests 258 00:10:15,570 --> 00:10:16,920 that are going out of our network 259 00:10:16,920 --> 00:10:18,030 and see what our employees 260 00:10:18,030 --> 00:10:20,070 inside of our organization are doing. 261 00:10:20,070 --> 00:10:22,800 For example, in one of the organizations I used to work at, 262 00:10:22,800 --> 00:10:24,930 you were not allowed to browse pornography 263 00:10:24,930 --> 00:10:27,330 or go to gambling websites when you were at work. 264 00:10:27,330 --> 00:10:30,390 And so all of their machines went through our proxy server, 265 00:10:30,390 --> 00:10:31,560 where we could check the sites 266 00:10:31,560 --> 00:10:32,820 that they were going to first, 267 00:10:32,820 --> 00:10:33,750 and if it was one of those sites 268 00:10:33,750 --> 00:10:35,130 that they weren't allowed to go to, 269 00:10:35,130 --> 00:10:37,410 we would block that connection and send them back a message 270 00:10:37,410 --> 00:10:39,630 saying, you're not authorized to see this. 271 00:10:39,630 --> 00:10:41,220 On the other hand, you can also use it 272 00:10:41,220 --> 00:10:42,420 from the other direction. 273 00:10:42,420 --> 00:10:44,430 As data is coming in from the web, 274 00:10:44,430 --> 00:10:46,020 you can actually check that data to make sure 275 00:10:46,020 --> 00:10:48,300 it doesn't have viruses or any other bad stuff 276 00:10:48,300 --> 00:10:51,000 before passing it on into your machines on the inside. 277 00:10:51,000 --> 00:10:54,150 So it is a great thing to use from a security perspective. 278 00:10:54,150 --> 00:10:56,490 Next, we need to talk about logging servers. 279 00:10:56,490 --> 00:10:59,130 And one of the key ways that we can create a logging server 280 00:10:59,130 --> 00:11:01,410 is to use this CS log protocol. 281 00:11:01,410 --> 00:11:02,880 Now as a system administrator, 282 00:11:02,880 --> 00:11:05,010 it's really important for us to be able to understand 283 00:11:05,010 --> 00:11:07,080 what things are happening on our network. 284 00:11:07,080 --> 00:11:09,390 And we do that by looking at the logs. 285 00:11:09,390 --> 00:11:11,280 Now, instead of having to go to every single server 286 00:11:11,280 --> 00:11:13,710 or workstation and read their logs individually, 287 00:11:13,710 --> 00:11:16,710 I can set up the CS log server and have all those devices 288 00:11:16,710 --> 00:11:19,680 send their data back to my centralized logging server 289 00:11:19,680 --> 00:11:21,180 at a regular interval. 290 00:11:21,180 --> 00:11:24,090 This can be done either every minute, every second, 291 00:11:24,090 --> 00:11:25,710 or whatever interval you really want 292 00:11:25,710 --> 00:11:27,390 depending on your configuration. 293 00:11:27,390 --> 00:11:29,670 But the key here is that you could set up a Linux server 294 00:11:29,670 --> 00:11:31,347 to be this centralized log server. 295 00:11:31,347 --> 00:11:33,150 And this is one of those server roles. 296 00:11:33,150 --> 00:11:35,640 And this is known as a CS log server. 297 00:11:35,640 --> 00:11:38,580 This makes it a lot easier for us to archive all those logs, 298 00:11:38,580 --> 00:11:39,930 especially if we have to prove that we're meeting 299 00:11:39,930 --> 00:11:41,640 certain service level agreements, 300 00:11:41,640 --> 00:11:44,760 or if we're trying to troubleshoot or diagnose an issue 301 00:11:44,760 --> 00:11:46,620 or verify that performance is acting the way 302 00:11:46,620 --> 00:11:47,550 it's supposed to, 303 00:11:47,550 --> 00:11:49,170 all that can be done a lot easier 304 00:11:49,170 --> 00:11:51,600 if I have centralized logging turned on. 305 00:11:51,600 --> 00:11:53,880 So with all this centralization, 306 00:11:53,880 --> 00:11:56,610 we can have our Linux servers, our Windows machines, 307 00:11:56,610 --> 00:11:58,200 all that stuff forwarding their logs 308 00:11:58,200 --> 00:12:00,180 into the single CS log server, 309 00:12:00,180 --> 00:12:02,490 and it's going to consolidate and store all those files 310 00:12:02,490 --> 00:12:04,530 where we can then query them and look through all of them 311 00:12:04,530 --> 00:12:06,090 in one place. 312 00:12:06,090 --> 00:12:08,910 The next thing we want to talk about is monitoring services. 313 00:12:08,910 --> 00:12:10,800 Now there's lots of different monitoring services 314 00:12:10,800 --> 00:12:12,540 available inside of Linux. 315 00:12:12,540 --> 00:12:13,980 Some of these services are designed 316 00:12:13,980 --> 00:12:15,660 for specific applications. 317 00:12:15,660 --> 00:12:17,940 For example, there's monitoring services set up 318 00:12:17,940 --> 00:12:20,160 just to look at your Apache web server. 319 00:12:20,160 --> 00:12:21,510 There's other ones that are set up 320 00:12:21,510 --> 00:12:23,850 to look at the entire Linux operating system. 321 00:12:23,850 --> 00:12:25,260 Depending on what you're doing, 322 00:12:25,260 --> 00:12:27,300 you can look at different monitoring services 323 00:12:27,300 --> 00:12:29,610 and different monitoring programs to see information 324 00:12:29,610 --> 00:12:32,700 about those different servers or server roles. 325 00:12:32,700 --> 00:12:35,460 For example, if you want to look at just Apache, 326 00:12:35,460 --> 00:12:37,380 you can look at ApacheTop. 327 00:12:37,380 --> 00:12:39,840 ApacheTop is going to provide log file analysis 328 00:12:39,840 --> 00:12:41,400 for your Apache web server, 329 00:12:41,400 --> 00:12:43,080 as well as information about different connection 330 00:12:43,080 --> 00:12:45,390 response times and things like that. 331 00:12:45,390 --> 00:12:47,670 Another thing you can use is Monit. 332 00:12:47,670 --> 00:12:50,250 Monit is a simple monitoring utility for Linux 333 00:12:50,250 --> 00:12:52,320 that watches hardware usage and directory 334 00:12:52,320 --> 00:12:53,520 and file information, 335 00:12:53,520 --> 00:12:54,990 and then it monitors the system 336 00:12:54,990 --> 00:12:57,060 inside of the known GUI tool 337 00:12:57,060 --> 00:12:58,260 that allows you to gather information 338 00:12:58,260 --> 00:13:00,690 on your system resources and how they're being used 339 00:13:00,690 --> 00:13:02,490 on a given Linux server. 340 00:13:02,490 --> 00:13:04,860 Now, these two tools are not the only ones out there, 341 00:13:04,860 --> 00:13:07,020 but I just wanted to kind of introduce you to the concept 342 00:13:07,020 --> 00:13:08,580 that there's lots of different tools out there 343 00:13:08,580 --> 00:13:10,920 for monitoring your CPU and memory usage, 344 00:13:10,920 --> 00:13:13,350 as well as the connections to, and from your Linux servers, 345 00:13:13,350 --> 00:13:15,360 depending on your use case. 346 00:13:15,360 --> 00:13:17,880 Next, we're going to talk about load balancing. 347 00:13:17,880 --> 00:13:19,590 Now there's also load balancing services 348 00:13:19,590 --> 00:13:21,180 that you can set up, and this will allow you 349 00:13:21,180 --> 00:13:23,040 to distribute inbound connection requests 350 00:13:23,040 --> 00:13:24,960 across multiple servers. 351 00:13:24,960 --> 00:13:26,220 Think about it this way. 352 00:13:26,220 --> 00:13:29,940 I have over 500,000 students at the time of this recording. 353 00:13:29,940 --> 00:13:32,070 They can't all connect to one single server 354 00:13:32,070 --> 00:13:33,240 and watch this course. 355 00:13:33,240 --> 00:13:34,680 It would crash the server. 356 00:13:34,680 --> 00:13:37,140 So instead, we have multiple servers set up. 357 00:13:37,140 --> 00:13:39,060 And when you go to diontraining.com, 358 00:13:39,060 --> 00:13:42,097 it distributes that load across all of my servers 359 00:13:42,097 --> 00:13:44,430 to be able to give you the best experience we can. 360 00:13:44,430 --> 00:13:46,920 This is the idea of how load balancing works. 361 00:13:46,920 --> 00:13:48,660 It's really common to use load balancing 362 00:13:48,660 --> 00:13:49,950 to distribute this connection 363 00:13:49,950 --> 00:13:51,600 among lots of different web servers 364 00:13:51,600 --> 00:13:54,060 or lots of different databases to ensure 365 00:13:54,060 --> 00:13:55,620 that you can then get a better performance 366 00:13:55,620 --> 00:13:57,270 for your end users. 367 00:13:57,270 --> 00:13:58,410 If you're running a web server, 368 00:13:58,410 --> 00:14:00,690 you don't want one single server being up 369 00:14:00,690 --> 00:14:02,100 to run all of your traffic, 370 00:14:02,100 --> 00:14:03,960 because that becomes a single point of failure. 371 00:14:03,960 --> 00:14:06,780 And if that server goes down or becomes overwhelmed, 372 00:14:06,780 --> 00:14:08,340 it means nobody in the world is going to be able 373 00:14:08,340 --> 00:14:09,600 to access your content. 374 00:14:09,600 --> 00:14:11,850 So you want to instead use load balancing 375 00:14:11,850 --> 00:14:14,580 and multiple web servers to alleviate this congestion 376 00:14:14,580 --> 00:14:17,760 and spread out the load across multiple devices. 377 00:14:17,760 --> 00:14:19,260 Now on your internal network, 378 00:14:19,260 --> 00:14:20,790 there's also lots of different things 379 00:14:20,790 --> 00:14:22,320 that we're going to find as well. 380 00:14:22,320 --> 00:14:25,080 For example, you're going to have things like database servers 381 00:14:25,080 --> 00:14:26,880 and storage area networks. 382 00:14:26,880 --> 00:14:28,440 These are also things that you're going to have 383 00:14:28,440 --> 00:14:29,730 inside your internal network. 384 00:14:29,730 --> 00:14:32,550 And a lot of these are running Linux as well. 385 00:14:32,550 --> 00:14:36,210 Each server inside of this cluster gets called a node. 386 00:14:36,210 --> 00:14:37,770 And if a single node goes down, 387 00:14:37,770 --> 00:14:40,140 the cluster can still remain up because you have multiple 388 00:14:40,140 --> 00:14:42,960 database servers or multiple storage area devices 389 00:14:42,960 --> 00:14:45,450 inside of this clustered array. 390 00:14:45,450 --> 00:14:47,520 This means that we can have better maintainability 391 00:14:47,520 --> 00:14:51,180 and availability of these devices inside of this cluster. 392 00:14:51,180 --> 00:14:53,850 Another thing you're often going to use inside of your network 393 00:14:53,850 --> 00:14:55,830 is file and print servers. 394 00:14:55,830 --> 00:14:58,290 Now file and print servers are going to allow you 395 00:14:58,290 --> 00:15:00,060 to do two basic things; 396 00:15:00,060 --> 00:15:02,010 file storage and printing documents 397 00:15:02,010 --> 00:15:03,630 to a centralized printer. 398 00:15:03,630 --> 00:15:05,640 Centralized printing is really popular, 399 00:15:05,640 --> 00:15:07,410 especially in large organizations 400 00:15:07,410 --> 00:15:09,390 because printers are really expensive. 401 00:15:09,390 --> 00:15:11,940 And if everybody has an individual printer on their desk, 402 00:15:11,940 --> 00:15:14,760 that is a very large capital expense that we have to have 403 00:15:14,760 --> 00:15:16,350 as well as a lot of maintenance. 404 00:15:16,350 --> 00:15:19,170 So instead, we might have one really large 405 00:15:19,170 --> 00:15:21,780 multifunction printer sitting on each floor 406 00:15:21,780 --> 00:15:22,860 of our office building, 407 00:15:22,860 --> 00:15:24,660 and we might have 50 or a hundred people 408 00:15:24,660 --> 00:15:26,280 using that one printer. 409 00:15:26,280 --> 00:15:28,890 This allows us to use a bigger, more expensive printer, 410 00:15:28,890 --> 00:15:30,330 but that more expensive printer 411 00:15:30,330 --> 00:15:31,800 can handle a lot more print volume, 412 00:15:31,800 --> 00:15:33,600 it doesn't break down nearly as often, 413 00:15:33,600 --> 00:15:35,400 and it's a lot easier to support. 414 00:15:35,400 --> 00:15:37,500 To do this though, you have to have a print server. 415 00:15:37,500 --> 00:15:39,270 And so when I print from my workstation, 416 00:15:39,270 --> 00:15:41,880 it goes to the print server, which could be running Linux. 417 00:15:41,880 --> 00:15:43,740 And then that goes over to the printer directly 418 00:15:43,740 --> 00:15:44,880 to print it out. 419 00:15:44,880 --> 00:15:47,670 This helps get your print costs down and also make sure 420 00:15:47,670 --> 00:15:49,440 that we have a more efficient print experience 421 00:15:49,440 --> 00:15:51,000 for all of our users. 422 00:15:51,000 --> 00:15:52,110 Now, on the other side, 423 00:15:52,110 --> 00:15:54,450 we also have to have file storage capability. 424 00:15:54,450 --> 00:15:56,880 And we do this using file servers. 425 00:15:56,880 --> 00:15:58,007 There's two main types of file servers 426 00:15:58,007 --> 00:16:00,600 you're going to come across inside of Linux. 427 00:16:00,600 --> 00:16:03,930 One is known as Samba and the other is called NFS. 428 00:16:03,930 --> 00:16:07,500 Now Samba is a Windows compatible file sharing system 429 00:16:07,500 --> 00:16:10,800 that runs on SMB or Server Message Block. 430 00:16:10,800 --> 00:16:13,260 If you have a Linux and Windows integrated system 431 00:16:13,260 --> 00:16:15,090 for all of your servers and endpoints, 432 00:16:15,090 --> 00:16:16,770 you're going to want to be using Samba 433 00:16:16,770 --> 00:16:18,090 to ensure that all of your devices 434 00:16:18,090 --> 00:16:20,010 can access your file share. 435 00:16:20,010 --> 00:16:22,200 Now, when it comes to Samba, there's two parts of it 436 00:16:22,200 --> 00:16:23,280 you have to think about. 437 00:16:23,280 --> 00:16:25,980 There's the server side, and there's the file side. 438 00:16:25,980 --> 00:16:28,410 If you're running a file server on a Linux server 439 00:16:28,410 --> 00:16:29,790 and you have Windows clients, 440 00:16:29,790 --> 00:16:31,800 you need to run Samba on that server 441 00:16:31,800 --> 00:16:33,900 to be able to communicate with those windows clients. 442 00:16:33,900 --> 00:16:36,120 But similarly, if you're using a Linux system 443 00:16:36,120 --> 00:16:37,590 as your desktop machine, 444 00:16:37,590 --> 00:16:39,840 and you're trying to connect to a Windows file server, 445 00:16:39,840 --> 00:16:41,730 you need to run the Samba client 446 00:16:41,730 --> 00:16:44,040 so you can read into that Windows environment 447 00:16:44,040 --> 00:16:45,630 and be able to access the files that are stored 448 00:16:45,630 --> 00:16:47,430 on that Windows server. 449 00:16:47,430 --> 00:16:50,010 Now, if your enterprise network is made up of only Unix 450 00:16:50,010 --> 00:16:53,940 and Linux workstations and servers, you can instead use NFS, 451 00:16:53,940 --> 00:16:56,130 which is Network File Sharing. 452 00:16:56,130 --> 00:16:58,890 NFS is a native Unix and Linux protocol 453 00:16:58,890 --> 00:17:01,410 that's used by workstations to access directories 454 00:17:01,410 --> 00:17:03,900 that are stored on Unix or Linux servers. 455 00:17:03,900 --> 00:17:05,550 Again, either way you do it, 456 00:17:05,550 --> 00:17:07,500 the idea here is to have a centralized place 457 00:17:07,500 --> 00:17:10,650 for files to be on a single server or a cluster of servers. 458 00:17:10,650 --> 00:17:13,020 And this makes the physical security and backups 459 00:17:13,020 --> 00:17:16,170 of those machines a lot easier to maintain. 460 00:17:16,170 --> 00:17:17,940 When you're configuring NFS, 461 00:17:17,940 --> 00:17:22,440 you're going to do this inside of the /etsy, /exports file. 462 00:17:22,440 --> 00:17:24,150 The next type of server we're going to talk about 463 00:17:24,150 --> 00:17:25,710 is database servers. 464 00:17:25,710 --> 00:17:28,020 Now databases can be internal or external, 465 00:17:28,020 --> 00:17:29,700 but in this case, we're going to talk specifically 466 00:17:29,700 --> 00:17:31,740 about internal databases. 467 00:17:31,740 --> 00:17:33,420 Now databases are going to be used to store 468 00:17:33,420 --> 00:17:34,950 large quantities of data, 469 00:17:34,950 --> 00:17:37,260 and this makes it easier for you to query the database 470 00:17:37,260 --> 00:17:38,970 and get the information out that you need 471 00:17:38,970 --> 00:17:40,470 by searching through it. 472 00:17:40,470 --> 00:17:42,390 There are two basic types of databases 473 00:17:42,390 --> 00:17:43,290 that you're going to encounter 474 00:17:43,290 --> 00:17:45,090 inside of your Linux environments. 475 00:17:45,090 --> 00:17:49,110 We have SQL databases and NoSQL databases. 476 00:17:49,110 --> 00:17:52,530 SQL databases are what we call structured databases. 477 00:17:52,530 --> 00:17:54,630 To communicate with an SQL database 478 00:17:54,630 --> 00:17:55,890 and be able to read from it, 479 00:17:55,890 --> 00:17:58,230 you're going to use the Structured Query Language, 480 00:17:58,230 --> 00:18:00,240 which is known as SQL. 481 00:18:00,240 --> 00:18:02,100 When you're using an SQL database, 482 00:18:02,100 --> 00:18:03,750 it's going to store all of its information 483 00:18:03,750 --> 00:18:06,510 inside of different tables that are related to each other. 484 00:18:06,510 --> 00:18:09,000 So we call these relational databases. 485 00:18:09,000 --> 00:18:10,380 Inside each of these tables, 486 00:18:10,380 --> 00:18:13,230 the data's going to be stored inside tables and columns, 487 00:18:13,230 --> 00:18:15,180 and it will be able to read and write information 488 00:18:15,180 --> 00:18:18,120 using SQL to and from these databases. 489 00:18:18,120 --> 00:18:19,620 Now, the second type of databases 490 00:18:19,620 --> 00:18:21,750 are known as NoSQL databases, 491 00:18:21,750 --> 00:18:24,150 and these are non relational databases. 492 00:18:24,150 --> 00:18:25,200 In these databases, 493 00:18:25,200 --> 00:18:27,330 there is no centralized, organized way 494 00:18:27,330 --> 00:18:29,220 of storing the data in them. 495 00:18:29,220 --> 00:18:31,033 Now you may be wondering, why would you want to use 496 00:18:31,033 --> 00:18:32,430 a NoSQL database? 497 00:18:32,430 --> 00:18:34,560 It seems like it's not a great idea. 498 00:18:34,560 --> 00:18:37,230 Well, NoSQL databases have a big place 499 00:18:37,230 --> 00:18:39,030 in machine learning and AI, 500 00:18:39,030 --> 00:18:41,580 and they're very, very popular in high velocity 501 00:18:41,580 --> 00:18:43,410 and high capacity systems. 502 00:18:43,410 --> 00:18:44,430 So you will run into them 503 00:18:44,430 --> 00:18:46,860 if you're working at a very large organization, 504 00:18:46,860 --> 00:18:50,250 dealing with big data sets in that big data world. 505 00:18:50,250 --> 00:18:52,800 Next, we're going to talk about VPN servers. 506 00:18:52,800 --> 00:18:55,500 Now VPNs are Virtual Private Networks. 507 00:18:55,500 --> 00:18:57,090 And if you're running a VPN server, 508 00:18:57,090 --> 00:18:58,410 this will allow remote users 509 00:18:58,410 --> 00:19:00,570 to connect to this internal company network 510 00:19:00,570 --> 00:19:02,820 and access all of your internal resources 511 00:19:02,820 --> 00:19:05,220 as if they' physically sitting at their desk 512 00:19:05,220 --> 00:19:07,140 of where that network location was. 513 00:19:07,140 --> 00:19:09,300 This is really useful when you're working from home 514 00:19:09,300 --> 00:19:10,770 or working from the road. 515 00:19:10,770 --> 00:19:13,410 For example, right now I'm actually sitting 516 00:19:13,410 --> 00:19:14,670 not in my office. 517 00:19:14,670 --> 00:19:16,770 And instead I'm connected back to my office 518 00:19:16,770 --> 00:19:19,650 over a VPN connection so I can access my email 519 00:19:19,650 --> 00:19:21,690 and other things like that, that I need. 520 00:19:21,690 --> 00:19:24,120 VPN services are really important 521 00:19:24,120 --> 00:19:25,770 because it allows you to have this trusted, 522 00:19:25,770 --> 00:19:27,840 secure tunnel from where you are, 523 00:19:27,840 --> 00:19:29,340 right now I'm in my home office, 524 00:19:29,340 --> 00:19:30,810 back to your corporate office 525 00:19:30,810 --> 00:19:32,910 and into your corporate environment. 526 00:19:32,910 --> 00:19:34,830 The final type of server we're going to talk about 527 00:19:34,830 --> 00:19:38,100 that you can host on your Linux machine is email servers. 528 00:19:38,100 --> 00:19:40,140 Now email services are a key component 529 00:19:40,140 --> 00:19:42,330 of business communications these days. 530 00:19:42,330 --> 00:19:45,000 Email servers are really responsible for the distribution 531 00:19:45,000 --> 00:19:47,250 of electronic mail within the organization 532 00:19:47,250 --> 00:19:49,950 or between organizations over the internet. 533 00:19:49,950 --> 00:19:51,420 There's really two parts to email; 534 00:19:51,420 --> 00:19:53,310 there's sending and there's receiving. 535 00:19:53,310 --> 00:19:55,080 And if you have a Linux server and you want to be able 536 00:19:55,080 --> 00:19:58,290 to have a sending server, you would set up Sendmail. 537 00:19:58,290 --> 00:20:00,120 If you want to be able to receive email, 538 00:20:00,120 --> 00:20:02,430 you would use something like Postfix. 539 00:20:02,430 --> 00:20:04,530 Now, each of these are going to use different email protocols 540 00:20:04,530 --> 00:20:06,720 that are common to all operating systems. 541 00:20:06,720 --> 00:20:09,720 If you're sending email, you do this using SMTP, 542 00:20:09,720 --> 00:20:11,970 which is the Simple Mail Transfer Protocol. 543 00:20:11,970 --> 00:20:13,350 If you're receiving email, 544 00:20:13,350 --> 00:20:16,980 you're going to do this using Post Office Protocol, or POP3, 545 00:20:16,980 --> 00:20:19,890 or you might use Internet Message Access Protocol, 546 00:20:19,890 --> 00:20:21,660 which is known as IMAP. 547 00:20:21,660 --> 00:20:24,180 All right, I know we covered a ton of information 548 00:20:24,180 --> 00:20:26,940 in this lesson, but really the key you need to know here 549 00:20:26,940 --> 00:20:30,330 is all a review from your A+ and Network+ studies. 550 00:20:30,330 --> 00:20:31,980 You need to understand that there are different types 551 00:20:31,980 --> 00:20:34,800 of servers you can run on a Linux machine. 552 00:20:34,800 --> 00:20:36,840 All these different services and all the different ports 553 00:20:36,840 --> 00:20:39,690 and protocols you learn back in A+ and Network+, 554 00:20:39,690 --> 00:20:41,340 they're all coming back right here 555 00:20:41,340 --> 00:20:43,050 as we start talking about how you can install 556 00:20:43,050 --> 00:20:45,360 these different servers and software packages 557 00:20:45,360 --> 00:20:47,943 to run these services on a Linux server.