Alpine Linux as a DHCP and DNS Server

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Alpine Linux as a DHCP and DNS Server.png

dnsmasq is a lightweight, easy-to-configure DHCP and DNS server. I'll demonstrate how to set up dnsmasq as both a DHCP and DNS server on a Linux system.

Procedure

Network Card Configuration :

ip address

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The physical interface eth1 is used to set up DHCP and DNS services.

cat >> /etc/network/interfaces << EOF
auto eth1
iface eth1 inet static
        address 192.168.0.1
        network 192.168.0.0
        netmark 255.255.255.0
        broadcast 192.168.0.255
EOF

Restart the networking to apply the settings.

rc-service networking restart

DNSMASQ Configuration :

Install dnsmasq:

sudo apk add dnsmasq

2023-03-29_084022.png

Configure dnsmasq:

The main configuration file for dnsmasq is /etc/dnsmasq.conf. Open this file with a text editor:

sudo vi /etc/dnsmasq.conf

Add or modify the following lines to configure dnsmasq as a DHCP and DNS server. Replace the placeholders with appropriate values for your network.

# DHCP configuration
dhcp-range=<start-IP>,<end-IP>,<netmask>,<lease-time>
dhcp-option=option:router,<router-IP>
dhcp-option=option:dns-server,<DNS-IP>

# DNS configuration
domain=<your-domain>
local=/<your-domain>/

Also, can save the file in a folder (/etc/dnsmasq.d) which end in .conf .

For example:

cat >> /etc/dnsmasq.d/eth1.conf << EOF

# DHCP configuration

dhcp-range=192.168.0.100,192.168.0.200,255.255.255.0,12h
dhcp-option=option:router,192.168.0.1
dhcp-option=option:dns-server,192.168.0.1

# DNS configuration

domain=local.lan
local=/local.lan/
EOF

Configure local DNS entries (optional):

If you want to add custom DNS entries for your local network, you can create a new file called /etc/hosts.dnsmasq and add the entries in the following format:

<IP-address> <hostname>.<domain> <alias>

For example:

192.168.0.10 server.local.lan server
192.168.0.20 nas.local.lan nas

Then, add the following line to /etc/dnsmasq.conf to use /etc/hosts.dnsmasq for local DNS resolution:

addn-hosts=/etc/hosts.dnsmasq

Start and enable dnsmasq:

rc-service dnsmasq start

/var/lib/misc/dnsmasq.leases: creating file
/var/lib/misc/dnsmasq.leases: correcting owner
Starting dnsmasq ...

rc-update add dnsmasq

service dnsmasq added to runlevel default

Perform client PC testing

Clients should receive IP addresses and DNS settings automatically when they connect, and any custom local DNS entries you configured should resolve correctly.

sudo rc-service networking restart

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Now, dnsmasq should be running as a DHCP and DNS server on network.

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