How To and Why Set Up a Static IP Address on GNU/Linux

Summary

This tutorial explains what a static IP address is, and why to use one. It also outlines how to set up a static IP address on GNU/Linux.

The steps in this tutorial have been tested on kubuntu (12.04, 14.04, 16.04, 20.04, 22.04) and mythbuntu (12.04, 14.04), and should work with many other GNU/Linux distributions.

This tutorial assumes that your computer is on a private home network that is connected to the Internet via a router.

Update 2023-02-25: Add method using nmcli command for Ubuntu 22.04 and later.

Update 2021-08-18: Add note regarding Ubuntu 20.04 also requiring edit of /etc/resolve.conf to resolve Internet hostnames.

Update 2021-01-08: Add "Appendix A: Router IP Address Reservation" section.

What is a Static IP Address?
Why Use a Static IP Address?
Acquiring Network Information
Setting Up Static IP Address
- Method A: nmcli - Network Manager Command Line Interface (Ubuntu 22.04+)
- Method B: /etc/network/interfaces File
References
Appendix A: Router IP Address Reservation

What is a Static IP Address?

A static Internet Protocol Address (IP address) is a fixed location at which a computer can be contacted on a network.

This fixed location must be unique on the network so that network traffic meant for the computer is sent only to that computer. This is similar to the way your home address is unique, so that your postal mail is delivered only to your home address.

Why Use a Static IP Address?

A static IP address is needed when a computer is to provide a service to other computers. Examples of services are a web page server, a MythTV backend server, and a calendar and address server.

In order for other computers to reliably contact the service on the computer, the computer must have a unique static (unchanging) IP address.

Advantages of a static IP address are:

Can provide services for other computers because computer is accessible at a known, unchanging IP address
Faster boot because no time spent waiting for a dynamic IP address

Disadvantages of a static IP address are:

More difficult to move computer to other networks because the computer network configuration will require changing
Requires more knowledge of networking to support

If other computers do not rely on services from your computer, or you often move your computer and use it on different networks, then staying with a dynamically assigned IP address is probably best.

Acquiring Network Information

Before we can set up a static IP address, we need to determine some information about your computer and the network to which the computer is connected.

The items that we will need to set up a static IP address are:

Network interface name
Network your computer is on
Gateway address
Network mask
Broadcast address
A range of addresses set aside for static IP addresses

Fortunately much of this information can be readily determined.

Open a terminal window.

In the K Desktop Environment (kubuntu) use menu option: K -> System -> Konsole (Terminal)

In XFCE (mythbuntu) use menu option: Applications -> System -> Xfce Terminal

TIP: Opening a terminal in other desktop environments

You can often open a terminal window using the following steps:

a) Press Alt+F2 to open a run command prompt
b) Enter "xterm" without the quotes

Query for the networking information.

Use either method.

Method A: ip command


        ip route

Sample output:


    default via 192.168.1.1 dev enp4s0 onlink
    169.254.0.0/16 dev enp4s0 scope link metric 1000
    192.168.1.0/24 dev enp4s0 proto kernel scope link src 192.168.1.54

Method B: netstat command (if net-tools package installed)


        sudo netstat -rn

Sample output:


    Kernel IP routing table
    Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
    0.0.0.0         192.168.1.1     0.0.0.0         UG        0 0          0 enp4s0
    169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 enp4s0
    192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 enp4s0

Determine the networking details.

From the either of the above commands we can learn the following:

enp4s0 - network interface name (other examples are enp0s31f6 and eth0)
192.168.1.1 - gateway address and address to use for Domain Name Server address (same as home router IP address)
192.168.1.0 - network provided by the home router (the first three numbers match the gateway)
/24 or 255.255.255.0 - network mask (a class C network for up to 254 devices)
192.168.1.255 - broadcast address (replace the last 0 in the network with a 255)

The above values are colour coded to help later when configuring the network interface.

TIP: Other Private Class C Networks

Private class C networks start with 192.168. Many home routers commonly use 192.168.1.x addresses, but values from 0 to 254 can be used (not just 1).

For example 192.168.0.254 is a valid class C network address on the private network 192.168.0.0.

Choose a static IP address.

To learn the range of IP addresses set aside by the router for static IP addresses, refer to your router documentation or login to your home router to check these settings. In general these are IP address outside of the range that is dynamically assigned by your home router.

From my experience with Linksys and D-Link routers, addresses with a last number of 51 to 64 have been outside the range of dynamically assigned addresses and are safe to use as a static IP address.

Choose a number that will be unique on your network (no two computers can use the same IP address).

For example, I chose the following static IP addresses for two different computers on my home network.

192.168.1.53 - My desktop computer
192.168.1.55 - My MythTV personal video recorder

Setting Up Static IP Address

We are now ready to set up the static IP address on the computer. For this example I used the network information determined above and the following IP address:

192.168.1.53 - static IP address.

Use either of the following methods.

Method A: nmcli - Network Manager Command Line Interface (Ubuntu 22.04+)

I use this method for Ubuntu 22.04 and later.

View current connection details.

nmcli connection show

Assign the static ip address.


sudo nmcli con add type ethernet con-name 'static-ip' \
     ifname enp4s0 ipv4.method manual \
     ipv4.addresses 192.168.1.53/24 gw4 192.168.1.1

Add the routing address.

sudo nmcli con mod static-ip ipv4.dns 192.168.1.1
Bring up the networking interface.

sudo nmcli con up id 'static-ip'
Confirm the change to the new networking values.

Use either:

ip a
or:

nmcli device show enp4s0

Test you can access the Internet.

In a terminal window enter:


    ping www.google.com

Use CTRL+C to cancel the ping commmand.

Sample output follows:


PING www.google.com (74.125.196.99) 56(84) bytes of data.
64 bytes from yk-in-f99.1e100.net (74.125.196.99): icmp_req=1 ttl=46 time=95.3 ms
64 bytes from yk-in-f99.1e100.net (74.125.196.99): icmp_req=2 ttl=46 time=94.9 ms
^C
--- www.google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 94.974/95.164/95.355/0.362 ms

Method B: /etc/network/interfaces File

I use this method for Ubuntu 20.04 and earlier.

Create a backup of your existing network configuration.

In a terminal window, enter the following commands:

cd /etc/network sudo cp -p interfaces interfaces.backup

Edit the /etc/network/interfaces file to define a static IP address.

TIP: Use any text editor you prefer.

Many text editors are available.

kate is commonly used with KDE desktops
gedit is often used on GNOME desktops
leafpad is a graphical editor I install and use on XFCE desktops
nano is an editor often available on all GNU/Linux distributions.

Edit the file with a command similar to the following:


    sudo nano /etc/network/interfaces

and make the content like the following lines.

Remember to replace the values with the ones you determined above.

---------- begin /etc/network/interfaces ----------


# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
# Note:  These two lines are the only lines needed for a
#        dynamically assigned (DHCP) IP address.
auto lo
iface lo inet loopback

# The primary network interface
auto enp4s0
iface enp4s0 inet static
address 192.168.1.53
network 192.168.1.0
netmask 255.255.255.0
broadcast 192.168.1.255
gateway 192.168.1.1
metric 0
dns-nameservers 192.168.1.1

---------- end /etc/network/interfaces ----------

Save file and exit editor.

Release the current IP address from the network interface.

sudo ip addr flush enp4s0
Restart the networking service.

Either use one of the following commands or reboot:

sudo /etc/init.d/networking restart
Or:

sudo systemctl restart networking.service

Verify the IP address is correct.


    sudo ifconfig enp4s0

Following is a sample of output from this command:


 enp4s0     Link encap:Ethernet  HWaddr bc:ae:c5:e1:4b:f1
          inet addr:192.168.1.53  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::beae:c5ff:fee1:4bf1/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:54384 errors:0 dropped:0 overruns:0 frame:0
          TX packets:32697 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:77236077 (77.2 MB)  TX bytes:2463869 (2.4 MB)

Test you can access the Internet.

In a terminal window enter:


    ping www.google.com

Use CTRL+C to cancel the ping commmand.

Sample output follows:


PING www.google.com (74.125.196.99) 56(84) bytes of data.
64 bytes from yk-in-f99.1e100.net (74.125.196.99): icmp_req=1 ttl=46 time=95.3 ms
64 bytes from yk-in-f99.1e100.net (74.125.196.99): icmp_req=2 ttl=46 time=94.9 ms
^C
--- www.google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 94.974/95.164/95.355/0.362 ms

NOTE: Cannot ping the google server?

If the ping command cannot contact the google server and indicates packet loss, then something is wrong with the network configuration.

If you are unable to resolve the problem, you can restore the backup(s) you made earlier in /etc/network/interfaces.backup and /etc/resolve.conf.backup and reboot to return to your previous network configuration.

NOTE: Some Distros Use systemd-resolved

Some distros like Ubuntu 20.04 include systemd-resolved as a local DNS server. This means you will need to also edit the /etc/resolve.conf file to be able to resolve hostnames on the Internet.

Make a backup of /etc/resolve.conf:

sudo cp -p /etc/resolve.conf /etc/resolve.conf.backup

Edit file /etc/resolve.conf:

sudo nano /etc/resolve.conf

Comment out the existing nameserver line and add in a new name nameserver line with your gateway / router's IP address. For example:

# Generated by NetworkManager #nameserver 127.0.0.53 nameserver 192.168.1.1
Save file and exit editor.

Reboot.

See also How to Resolve “Temporary failure in name resolution” Issue.

References

While setting up a static IP address, I found the following references useful:

Appendix A: Router IP Address Reservation

Many modern routers support IP address reservation. If your router supports this feature then you have another method to set a static IP address for a computer. With this method there are no file changes required on the Linux computer.

Determine the MAC address for the computer.

Retrieve network information for the Ethernet card.

ifconfig

Following is a sample of output from this command:


    enp4s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.1.107  netmask 255.255.255.0  broadcast 192.168.1.255
            inet6 fe80::d836:16f4:af1d:5fa8  prefixlen 64  scopeid 0x20<link>
            ether dc:a6:32:8e:d2:c3  txqueuelen 1000  (Ethernet)
            RX packets 114  bytes 16015 (15.6 KiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 74  bytes 10490 (10.2 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

    lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
            inet 127.0.0.1  netmask 255.0.0.0
            inet6 ::1  prefixlen 128  scopeid 0x10<host>
            loop  txqueuelen 1000  (Local Loopback)
            RX packets 0  bytes 0 (0.0 B)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 0  bytes 0 (0.0 B)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

In the above output the MAC address for the ethernet card is dc:a6:32:8e:d2:c3

Reserve a static IP address for a computer in the router's configuration.

For this example we use static IP address: 192.168.1.53

The steps vary for each router and usually involve opening a web browser, logging into the router, locating the section for assigning/reserving static IP addresses, and then creating a record to pair a MAC address with a static IP address.

Following are high level instructions I used with my TP-LINK Archer C7 Wireless AC1750 Dual Band Gigabit Router:
1. Open a web browser and visit router home page: http://192.168.1.1
2. Login with the router admin account and password.
3. Locate the section to set a static IP address.
  
  For my router this is under DHCP -> Address Reservation.
4. Add new record for MAC Address and static IP address
```
        MAC Address         Reserved IP Address
        b8-27-eb-7f-bf-62   192.168.1.53
        
```
5. Reboot router.
  
  Many routers require a reboot or power cycle of the router to activate router configuration changes.
6. Reboot computer.
  
  This enables computer to be assigned the static IP address that is configured in the router.

The Medusa Deception novel - free first in series

How To and Why Set Up a Static IP Address on GNU/Linux

Summary

Contents

What is a Static IP Address?

Why Use a Static IP Address?

Acquiring Network Information

Setting Up Static IP Address

Method A: nmcli - Network Manager Command Line Interface (Ubuntu 22.04+)

Method B: /etc/network/interfaces File

References

Appendix A: Router IP Address Reservation