DNS & DHCP CONFIGURATION

Transcription

1 WELCOME

2 DNS & DHCP CONFIGURATION

3 Group Members Anmol Nazakat Ameena Fatima Shakeel ur Rehman Gulraiz Azam Irfan Ullah BSIT-F14-E78 BSIT-F14-E100 BSIT-F14-E66 BSIT-F14-E69 BSIT-F14-E79 3

4 Today s Agenda What We Are Going to Do We are going to install and Configure Dynamic Host Configuration Protocol and Domain Name System 1. DHCP Installation & Configuration Install ISC DHCP Server in Ubuntu Server and Configure it to automatically assign IP Addresses to the hosts 2. DNS Installation & Configuration Install DNS Sever in Ubuntu and Configure Name Servers. 3. Package Management Understand Package Manage in Ubuntu Linux and use Package Manager 4

5 DHCP (Dynamic Host Configuration protocol) The Dynamic Host Configuration Protocol (DHCP) is a network service that enables host computers to be automatically assigned settings from a server as opposed to manually configuring each network host. Computers configured to be DHCP clients have no control over the settings they receive from the DHCP server, and the configuration is transparent to the computer's user. 5

6 DHCP ILLUSTRATION

7 ISC DHCP ISC DHCP is a collection of software that implements all aspects of the DHCP (Dynamic Host Configuration Protocol) suite. It includes: 1 2 DHCP Server which receives clients requests and replies to them. DHCP Client which can be bundled with the operating system of a client computer or other IP capable device and which sends configuration requests to the server. Most devices and operating systems already have DHCP clients included. 3 DHCP Relay Agent which passes DHCP requests from one LAN to another so that there need not be a DHCP server on every LAN. 7

8 SETTINGS PROVIDED BY DHCP Most Common Settings Provided By DHCP Server to DHCP Clients Includes However, a DHCP server can also supply configuration properties such as: 1 IP Address and Netmask 1 Host Name 2 3 IP Address of the default-gateway to use IP Addresses of the DNS servers to use Domain Name Time Server Print Server 8

9 The advantage of using DHCP is that ADVANTAGES OF DHCP 1 Changes to the network for example a change in the address of the DNS server, need only be changed at the DHCP server, and all network hosts will be reconfigured the next time their DHCP clients poll the DHCP server. 2 Easier to integrate new computers As an added advantage, it is also easier to integrate new computers into the network, as there is no need to check for the availability of an IP address. 3 Conflicts Conflicts in IP address allocation are also reduced. 9

10 IP ALLOCATION METHODS OF DHCP A DHCP server can provide configuration settings using the following methods: Manual allocation (MAC address) This method entails using DHCP to identify the unique hardware address of each network card connected to the network and then continually supplying a constant configuration each time the DHCP client makes a request to the DHCP server using that network device. This ensures that a particular address is assigned automatically to that network card, based on it's MAC address. Dynamic allocation (address pool) In this method, the DHCP server will assign an IP address from a pool of addresses (sometimes also called a range or scope) for a period of time or lease, that is configured on the server or until the client informs the server that it doesn't need the address anymore. This way, the clients will be receiving their configuration properties dynamically and on a "first come, first served" basis. Automatic allocation Using this method, the DHCP automatically assigns an IP address permanently to a device, selecting it from a pool of available addresses. Usually DHCP is used to assign a temporary address to a client, but a DHCP server can allow an infinite lease time. 10

11 INSTALLATION OF DHCP At a terminal prompt, enter the following command to install dhcpd: irfan@iux~:$ sudo apt-get install isc-dhcp-server The default configuration file is /etc/dhcp/dhcpd.conf edit it to suit your needs and particular configuration. 11

12 CONFIGURATION OF DHCP The default configuration file is /etc/dhcp/dhcpd.conf edit it to suit your needs and particular configuration. You also may need to edit /etc/default/isc-dhcp-server to specify the interfaces dhcpd should listen to. sudo nano /etc/dhcp/dhcpd.conf Enter Password for irfan: # minimal sample /etc/dhcp/dhcpd.conf default-lease-time 600; max-lease-time 7200; subnet netmask { range ; option routers ; option domain-name-servers sandbox.example.com; option domain-name "example.com"; } 12

13 RESTART DHCP This will result in the DHCP server giving clients an IP address from the range The server will also "advise" the client to use as the default-gateway and and as its DNS servers. After make changes to the configuration file resrart the server sudo systemctl restart isc-dhcp-server 13

14 CHECK STATUS OF DHCP Check status of dhcp server 14

15 D N S

16 DOMAIN NAME SERVICE DNS What is Domain Name Service Domain Name Service (DNS) is an Internet service that maps IP addresses and fully qualified domain names (FQDN) to one another. In this way, DNS alleviates the need to remember IP addresses. Computers that run DNS are called name servers. 16

17 DNS ON DEBIAN/UBUNTU Ubuntu ships with BIND (Berkley Internet Naming Daemon), the most common program used for maintaining a name server on Linux. Installation At a terminal prompt, enter the following command to install dns: irfan@iuxsandbox~:$ sudo apt-get install bind9 A very useful package for testing and troubleshooting DNS issues is the dnsutils package. Very often these tools will be installed already, but to check and/or install dnsutils enter the following: irfan@iuxsandbox~:$ sudo apt-get install dnsutils 17

18 CONFIGURATION METHODS There are many ways to configure BIND9. Some of the most common configurations are a caching nameserver, primary master, and as a secondary master. 1 2 Cashing Nameserver When configured as a caching nameserver BIND9 will find the answer to name queries and remember the answer when the domain is queried again. Primary Master Nameserver As a primary master server BIND9 reads the data for a zone from a file on it's host and is authoritative for that zone. 3 Secondary Master Nameserver In a secondary master configuration BIND9 gets the zone data from another nameserver authoritative for the zone. 18

19 OVERVIEW The DNS configuration files are stored in the /etc/bind directory. The primary configuration file is /etc/bind/named.conf 1 2 The include line specifies the filename which contains the DNS options. The directory line in the /etc/bind/named.conf.options file tells DNS where to look for files. The file named /etc/bind/db.root describes the root nameservers in the world. The zone section defines a master server, and it is stored in a file mentioned in the file option. 3 It is possible to configure the same server to be a caching name server, primary master, and secondary master. 19

20 CASHING SERVER The default configuration is setup to act as a caching server. All that is required is simply adding the IP Addresses of your ISP's DNS servers. Simply uncomment and edit the following in /etc/bind/named.conf.options forwarders{ ; ; }; Now restart the DNS server, to enable the new configuration. irfan@iuxsandbox~:$ sudo systemctl restart bind9.service 20

21 TESTING CASHING SERVER After installing BIND9 use dig against the loopback interface to make sure it is listening on port 53. From a terminal prompt: irfan@iuxsandbox~:$ dig x ; <<>> DiG P4-Ubuntu <<>> -x ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: ;; Query time: 237 msec ;; SERVER: #53( ) ;; WHEN: Fri Jan 19 21:52:43 PKT 2018 ;; MSG SIZE rcvd:

22 PRIMARY MASTER DNS SERVER In this section BIND9 will be configured as the Primary Master for the domain example.com Turning BIND9 into a Primary Master server, the first step is to edit /etc/bind/named.conf.local: irfan@iuxsandbox~:$ sudo nano /etc/bind/named.conf.local zone example.com { type master; file /etc/bind/db.example.com ; }; Use default db.local file as zone template file irfan@iuxsandbox~:$ cp /etc/bind/db.local /etc/bind/db.example.com 22

23 Create an A record for the base domain, example.com. Also, create an A record for ns.example.com, the name server in this example: ; ; BIND data file for example.com ; $TTL IN SOA example.com. root.example.com. ( 2 ; Serial ; Refresh ; Retry ; Expire ) ; Negative Cache TTL IN A IN NS IN A IN AAAA ::1 ns IN A Now restart the bind to changes take effect irfan@iuxsandbox~:$ sudo systemctl restart bind9.service 23

24 Reverse Zone File Now that the zone is setup and resolving names to IP Adresses a Reverse zone is also required. A Reverse zone allows DNS to resolve an address to a name. Edit /etc/bind/named.conf.local and add the following: zone in-addr.arpa { type master; file /etc/bind/db.10 ; }; Now create the /etc/bind/db.10 irfan@iuxsandbox~:$ sudo /etc/bind/db.127 /etc/bind/db.10 24

25 DB.10 Zone File Now edit the /etc/bind/db.10 ; ; BIND reverse data file for local XXX net ; $TTL IN SOA ns.example.com. root.example.com. ( 2 ; Serial ; Refresh ; Retry ; Expire ) ; Negative Cache TTL IN NS ns. 10 IN PTR ns.example.com. Now restart bind irfan@iuxsandbox~:$ sudo systemctl restart bind 25

26 SECONDRY MASTER DNS Add the allow-transfer option to the example Forward and Reverse zone definitions in /etc/bind/named.conf.local: zone "example.com" { type master; file "/etc/bind/db.example.com"; allow-transfer { ; }; }; zone in-addr.arpa" { type master; file "/etc/bind/db.10"; allow-transfer { ; }; }; Now restart bind irfan@iuxsandbox~:$ sudo systemctl restart bind 26

27 SECONDRY MASTER DNS Now same as Primary Server edit the slave server on zone "example.com" { type slave; file "db.example.com"; masters { ; }; }; zone in-addr.arpa" { type slave; file "db.10"; allow-transfer { ; }; }; Now restart bind irfan@iuxsandbox~:$ sudo systemctl restart bind 27

28 THANKS 28