Netzwerk
How to set up static IP address on Debian Linux 10/11
The procedure is as follows to set up and configure a static IP information:
- Open the terminal application.
- Log in to remote or server using ssh command.
- Backup /etc/network/interfaces file running sudo cp /etc/network/interfaces /root/
- Edit the /etc/network/interfaces
- Configure static IP address for enp0s5 Ethernet interface: address 192.168.2.249
- Add subnet mask: netmask 255.255.255.0
- Set up default gateway IP: gateway 192.168.2.254
- Finally add DNS resolver IP: dns-nameservers 192.168.2.254 8.8.8.8 1.1.1.1
Let us see all commands and examples in details.
Finding your network interfaces name on Debian Linux
Use the ip command as follows to show/display available Ethernet network interfaces:
ip -c link show
Also, we can try the following Linux command to show a list of network cards:
sudo lshw -class network -short
# Filter results using grep/egrep regex command
lspci | grep -E -i --color 'network|ethernet|wireless|wi-fi'
ip -br -c link show
Note down the Debian Linux interface name and type the following ip command to see the current IP address assinged to that network interface:
ip -c addr show enp0s5
Configuring Static IP on Debian 10 or 11
The /etc/network/interfaces[/file] contains network interface configuration information for Debian Linux. Hence, edit the file:
sudo vim /etc/network/interfaces
## OR ##
sudo nano /etc/network/interfaces
Look for the primary network interface enp0s5:
allow-hotplug enp0s5
iface enp0s5 inet dhcp
Remove dhcp and allow-hotplug lines. Append the following configuration to set up/add new static IP on Debian Linux 10/11. Here is my sample config file:
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto enp0s5
iface enp0s5 inet static
address 192.168.2.236
netmask 255.255.255.0
gateway 192.168.2.254
dns-domain sweet.home
dns-nameservers 192.168.2.254 1.1.1.1 8.8.8.8
Save and close the file when using vim/vi text editor.
Restart networking service on Debian Linux to switch from DHCP to static IP config
Warning: Do not run the following over ssh based session as you will disconnect.
Use the systemctl command as follows:
sudo systemctl restart networking.service
Make sure service restarted without any errors. Hence, type the following command:sudo systemctl status networking.service
Sample session:
● networking.service - Raise network interfaces
Loaded: loaded (/lib/systemd/system/networking.service; enabled; vendor preset: enabled)
Active: active (exited) since Wed 2021-01-27 23:10:00 IST; 1min 38s ago
Docs: man:interfaces(5)
Process: 1104 ExecStart=/sbin/ifup -a --read-environment (code=exited, status=0/SUCCESS)
Main PID: 1104 (code=exited, status=0/SUCCESS)
See your new IP address assigned on Debian Linux
Again type the following ip command:
ip -c addr show
ip -c addr show enp0s5
When you change your IP address, you need to restart other services such as Nginx, SSH, etc. It all depends upon how you configured those services with IP binding. Make sure you adjust the firewall settings too.
A note about /etc/network/interfaces.d/ directory
WARNING! The following is an advanced configuration and is only recommended if you know various networking concepts. The nixCraft or author is not responsible for network connectivity loss.
You can place the network config in a separate file under /etc/network/interfaces.d/. I tested the following with Debian 11 with source keyword:
source /etc/network/interfaces.d/*
In other words, config lines beginning with “source” are used to include stanzas from other files. So configuration can be split into many files for ease of management. The word “source” is followed by the path of a file to be sourced. Shell wildcards can be used. Here is how /etc/network/interfaces looks now:
sudo cat /etc/network/interfaces
Outputs:
# 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
Here is my servers bridge network config file named /etc/network/interfaces.d/br0
sudo vim /etc/network/interfaces.d/br0
Append the following config to create br0 interface using eno1 Ethernet interface. For example:
auto br0
iface br0 inet static
address 192.168.2.19
broadcast 192.168.2.255
netmask 255.255.255.0
gateway 192.168.2.254
# If the resolvconf package is installed, you should not edit
# the resolv.conf configuration file manually. Set name server here
dns-nameservers 192.168.2.236 192.168.2.237
dns-domain sweet.home
# If you have multiple interfaces such as eth0 and eth1
# bridge_ports eth0 eth1
bridge_ports eno1
bridge_stp off # disable Spanning Tree Protocol
bridge_waitport 0 # no delay before a port becomes available
bridge_fd 0 # no forwarding delay
Then restart networking service on Debian Linux or reboot the Linux machine using the shutdown command/reboot command. For instance:
sudo reboot
OR
systemctl restart networking.service
Conclusion
You learned how to convert the existing DHCP to static IP address settings on Debian Linux version 9/10/11. See Debian Linux man page online or type the following command:
man interfaces
man nmcli
Finding NIC name and IP assigned by the DHCP server on Debian Linux