By default, the Debian 10 installer configures the network via DHCP. This causes the server’s IP to change with each reboot unless its IP is reserved in the Router. In my case, the network configuration of certain devices I prefer to configure manually on the device itself, and my Router does not allow to reserve more than 8 IPs so it becomes unfeasible to reserve IPs for all devices in my house.
Let’s see how to change the network configuration of the server so that it always has the same IP. For the moment, you can check what the current configuration is with the command:
$ ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:e0:4c:0e:5f:07 brd ff:ff:ff:ff:ff:ff inet 192.168.1.2/24 brd 192.168.1.255 scope global enp2s0 valid_lft forever preferred_lft forever inet6 fe80::2e0:4cff:fe0e:5f07/64 scope link valid_lft forever preferred_lft forever
Keep the interface whose
inet complies with the usual range of IPs in your network. In my case
Assigning a static IP
Once the interface has been identified. Open the network configuration file with the command:
$ sudo nano /etc/network/interfaces
nano text editor will be shown with the file more or less as follows:
# This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). source /etc/network/interfaces.d/* # The loopback network interface auto lo iface lo inet loopback # The primary network interface allow-hotplug enp2s0 iface enp2s0 inet dhcp
Knowing the interface to modify (in my case
enp2s0), modify the
dhcp part to add the manual configuration, and change
auto so you don’t have to restart the server with every configuration change.
# This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). source /etc/network/interfaces.d/* # The loopback network interface auto lo iface lo inet loopback # The primary network interface auto enp2s0 iface enp2s0 inet static address 192.168.1.2 netmask 255.255.255.0 network 192.168.1.1 broadcast 192.168.1.255 gateway 192.168.1.1
Change each field to the data corresponding to your network and your interface.
Then save the file with the F3 key and close the text editor with F2.
Modify the DNS server
If you also want to modify the DNS server used by the device for DNS resolution, execute the following command:
$ sudo nano /etc/resolv.conf
In the text editor, add or modify as many
nameserver lines as DNS servers you want to use. For example:
domain Home search Home nameserver 126.96.36.199 nameserver 188.8.131.52
In my case, I let the Router be in charge of assigning the DNS server that I previously configured on it, so I point to the Router’s gateway:
domain Home search Home nameserver 192.168.1.1
Again, save with F3 and came out with F2.
To apply the changes, execute these commands with the appropriate interface:
$ sudo ifdown enp2s0 $ sudo ifup enp2s0
You can check that the changes have been applied by running the command again:
$ ip a
You will see that the interface is now assigned the IP configured in previous steps.
As for the DNS server. You can execute a simple
ping command to see if any domain is resolved:
$ ping -c3 danielmartingonzalez.com PING danielmartingonzalez.com (184.108.40.206) 56(84) bytes of data. 64 bytes from 220.127.116.11 (18.104.22.168): icmp_seq=1 ttl=57 time=11.2 ms 64 bytes from 22.214.171.124 (126.96.36.199): icmp_seq=2 ttl=57 time=10.9 ms 64 bytes from 188.8.131.52 (184.108.40.206): icmp_seq=3 ttl=57 time=10.8 ms --- danielmartingonzalez.com ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 5ms rtt min/avg/max/mdev = 10.796/10.941/11.157/0.177 ms
Our machine with Debian will now have a manual network configuration that will facilitate its management. To do this, you only need to modify two files and restart the network interface. This knowledge will be useful in the future for next articles that will require the device itself to act as a DNS server. But that will be seen later.