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--- scgc:laboratoare:01 [2018/02/27 17:47]
victor.ciurel Minor consistency changes
+++ scgc:laboratoare:01 [2021/10/27 14:07] (current)
maria.mihailescu
@@ Line 1: / Line 1: @@
-====== Laboratory 01. DNS ======
+====== Naming Services: DNS ======
 ===== Lab Setup =====
-  * We will be using two virtual machines in the [[http://cloud.curs.pub.ro/|faculty's cloud]].
+  * We will be using two virtual machines in the [[http://cloud.grid.pub.ro/|faculty's cloud]].
-  * When creating a virtual machine follow the steps in this [[https://cloud.curs.pub.ro/about/tutorial-for-students/|tutorial]].
   * Create two VMs (one will be our DNS master server and one will be our DNS slave server)
   * When creating a virtual machine in the Launch Instance window:
     * Select **Boot from image** in **Instance Boot Source** section
-    * For the master VM select **Debian 8.6** in **Image Name** section
+    * For the master VM select **Debian 10.3** in **Image Name** section
     * For the slave VM select **Centos 7** in **Image Name** section
+    * Select the **m1.small** flavor for both VMs.
+  * The usernames for connecting to the VMs are:
+    * ''debian'' for **Debian 10.3**
+    * ''student'' for **CentOS 7**
   * For ease of use we recommend adding entries in the ''/etc/hosts'' file corresponding to the slave and master VMs
     * ''<ip_master> master''
@@ Line 122: / Line 125: @@
 It is noteworthy, that dig and host do not use ''/etc/nsswitch.conf'' for querying DNS servers and they do not use the system's DNS resolver, which is usually a library. We can see this from the following commands:
 <code>
-root@master:~# strace -e open host acs.pub.ro
+root@master:~# strace -e openat host acs.pub.ro
 [...]
-open("/etc/resolv.conf", O_RDONLY)      = 6
+openat(AT_FDCWD, "/etc/resolv.conf", O_RDONLY)      = 6
 acs.pub.ro has address 141.85.227.151
 acs.pub.ro mail is handled by 10 mx.acs.pub.ro.
 [...]
-root@master:~# strace -e open ping -c 1 acs.pub.ro
+root@master:~# strace -e openat ping -c 1 acs.pub.ro
 [...]
-open("/etc/resolv.conf", O_RDONLY|O_CLOEXEC) = 4
+openat(AT_FDCWD, "/etc/resolv.conf", O_RDONLY|O_CLOEXEC) = 4
-open("/etc/resolv.conf", O_RDONLY|O_CLOEXEC) = 4
+openat(AT_FDCWD, "/etc/resolv.conf", O_RDONLY|O_CLOEXEC) = 4
-open("/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = 4
+openat(AT_FDCWD, "/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = 4
 [...]
-open("/etc/host.conf", O_RDONLY|O_CLOEXEC) = 4
+openat(AT_FDCWD, "/etc/host.conf", O_RDONLY|O_CLOEXEC) = 4
-open("/etc/hosts", O_RDONLY|O_CLOEXEC)  = 4
+openat(AT_FDCWD, "/etc/hosts", O_RDONLY|O_CLOEXEC)  = 4
-open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 4
+openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 4
-open("/lib/x86_64-linux-gnu/libnss_dns.so.2", O_RDONLY|O_CLOEXEC) = 4
+openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libnss_dns.so.2", O_RDONLY|O_CLOEXEC) = 4
-open("/lib/x86_64-linux-gnu/libresolv.so.2", O_RDONLY|O_CLOEXEC) = 4
+openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libresolv.so.2", O_RDONLY|O_CLOEXEC) = 4
 PING acs.pub.ro (141.85.227.151) 56(84) bytes of data.
-open("/etc/hosts", O_RDONLY|O_CLOEXEC)  = 4
+openat(AT_FDCWD, "/etc/hosts", O_RDONLY|O_CLOEXEC)  = 4
 bytes from acs.pub.ro (141.85.227.151): icmp_seq=1 ttl=62 time=0.688 ms
@@ Line 196: / Line 199: @@
 	type master;
 	file "/etc/bind/db.scgc.ro"; # zone file path
-}
+};
 </file>
@@ Line 290: / Line 293: @@
 Now we should be able to test our DNS server. We will be using //host//, however feel free to use //dig// or any other command to test your server:
 <code>
-root@master:~# host www.scgc.ro 10.9.107.151
+root@master:~# host www.scgc.ro localhost
 Using domain server:
 Name: 10.9.107.151
@@ Line 297: / Line 300: @@
 www.scgc.ro has address 10.9.107.151
-root@master:~# host -t ns scgc.ro 10.9.107.151
+root@master:~# host -t ns scgc.ro localhost
 Using domain server:
 Name: 10.9.107.151
@@ Line 304: / Line 307: @@
 scgc.ro name server ns1.scgc.ro.
-root@master:~# host ns1.scgc.ro 10.9.107.151
+root@master:~# host ns1.scgc.ro localhost
 Using domain server:
 Name: 10.9.107.151
@@ Line 315: / Line 318: @@
 Now let's try to query from outside the server. We will test that the **slave** VM will receive the same response(replace with the appropriate name and IP address):
 <code>
-[root@slave ~]# host www.scgc.ro 10.9.107.151
+[root@slave ~]# host www.scgc.ro master
 Using domain server:
 Name: 10.9.107.151
@@ Line 341: / Line 344: @@
 <code>
-root@master:~# host google.com 10.9.107.151
+root@master:~# host google.com localhost
 Using domain server:
 Name: 10.9.107.151
@@ Line 355: / Line 358: @@
 google.com mail is handled by 20 alt1.aspmx.l.google.com.
-[root@slave ~]# host google.com 10.9.107.151
+[root@slave ~]# host google.com master
 Using domain server:
 Name: 10.9.107.151
@@ Line 386: / Line 389: @@
 <code>
-[root@slave ~]# host google.com 10.9.107.151
+[root@slave ~]# host google.com master
 Using domain server:
 Name: 10.9.107.151
@@ Line 408: / Line 411: @@
 === 4.1 [10p] Setup master DNS server ===
-Configure a DNS server on the client VM similarly to the master VM server, which will answer for queries about ''lab1.scgc.ro''. Your DNS zone must have at least an A record and a NS record for this exercise.
+Configure a new DNS zone on the master VM similarly to the previous one, which will answer for queries about ''lab1.scgc.ro''. Your DNS zone must have at least an A record and a NS record for this exercise.
 === 4.2 [10p] Zone transfer ===
@@ Line 414: / Line 417: @@
 The slave VM has a Centos 7 operating system, which has some differences in the setup of the DNS server.
-To install the *bind* use the following command:
+To install **BIND** use the following command:
 <code>
 yum install bind
@@ Line 421: / Line 424: @@
 On Red-Hat-based distributions bind will have the following characteristics:
-  * Service name: ''named''
+  * Service name: **named**
-  * Main configuration and zone names file: ''/etc/named.conf''
+  * Main configuration and zone names file: **/etc/named.conf**
-  * Default zone file location: ''/var/named/''
+  * Default zone file location: **/var/named/**
 In order to transfer the zone from the master server, we need to make the following configurations:

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scgc/laboratoare/01.1519746442.txt.gz · Last modified: 2018/02/27 17:47 by victor.ciurel

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