# Chapter 8. Install and Configure Dnsmasq

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## 目錄
- [Installing Dnsmasq on Ubuntu 18.04](#Step1)

- [Adding DNS records to Dnsmasq](#Step2)

- [Testing Dnsmasq DNS functionality](#Step3)

- [Configure Dnsmasq as DHCP Server](#Step4)

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<h1 id="Step 1">Installing Dnsmasq on Ubuntu 18.04</h2>

Run the following commands to disable the resolved service:

$ `sudo systemctl disable systemd-resolved`

$ `sudo systemctl stop systemd-resolved`

Also, remove the symlinked resolv.conf file
$ `ls -lh /etc/resolv.conf `

lrwxrwxrwx 1 root root 39 Aug 8 15:52 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

$ `sudo rm /etc/resolv.conf`

Then create new resolv.conf file.

$ `sudo nano /etc/resolv.conf`

nameserver 8.8.8.8

$ `sudo apt-get install dnsmasq`

$ `sudo nano /etc/dnsmasq.conf`

If you want to enable DNSSEC validation and caching, uncomment

#dnssec

Make any other changes you see relevant and restart dnsmasq when done:

$ `sudo systemctl restart dnsmasq`

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<h1 id="Step 2">Adding DNS records to Dnsmasq</h2>

$ `sudo nano /etc/hosts`

10.1.3.4 server1.mypridomain.com
10.1.4.4 erp.mypridomain.com
192.168.10.2 checkout.mypridomain.com
192.168.4.3 hello.world

$ `sudo systemctl restart dnsmasq`

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<h1 id="Step 3">Testing Dnsmasq DNS functionality</h2>

$ `sudo nano /etc/resolv.conf`

nameserver 127.0.0.1
nameserver 8.8.8.8

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<h1 id="Step 4">Configure Dnsmasq as DHCP Server</h2>

* Default gateway IP address
* DNS server IP address (Probably Dnsmasq or different DNS server)
* Network Subnet mask
* DHCP Addresses range
* NTP server

See below example

$ `sudo nano /etc/dnsmasq.conf`

dhcp-range=192.168.40.130,192.168.40.230,24h
dhcp-option=option:router,192.168.40.254
dhcp-option=option:dns-server,192.168.40.254
dhcp-option=option:netmask,255.255.255.0

Restart dnsmasq and configure clients to obtain an IP address from this server.

$ `sudo systemctl restart dnsmasq`

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