I have a number of CentOS 7 servers that comprise a FreeIPA domain on a VirtualBox host-only network. Whenever I start a server though, it is liable to pick up an IP address that I’ve already assigned to another server (which is currently powered off) in /etc/hosts.
How do I assign it a specific static IP address?
In CentOS 7, you can use the Network Manager Text User Interface (nmtui) to edit the network settings. Here’s the first thing I tried, which wasn’t quite right:
# nmtui
- Edit a connection
- Select a connection, e.g. enp0s3
- IPv4 Configuration
- Change from Automatic to Manual
- Select Show
- Enter 192.168.56.109/32 for addresses
- Enter 192.168.56.255 for the gateway
When I used those settings, it didn’t work. No route to host, etc. I looked at the network interface settings via a different method:
# ip addr show
The brd (broadcast) address listed was the same as my ip address, 192.168.56.109, which was unexpected and probably why it wasn’t working!
I ran nmtui again and changed the address from 192.168.56.109/32 to 192.168.56.109/24 and it worked.
Since the /32 is interpreted as the subnet mask, it created a subnet with an address range of 1, and the broadcast address would be the same as the ip address. Specifying a subnet mask of /24 creates a subnet with 256 addresses, and a broadcast address of 192.168.56.255 (the same as was listed for the other machines on the virtual network that were using DHCP).