I want to force a netmask on my Ubuntu machine. For example, I want 18.104.22.168 to get a netmask of 255.255.255.0
I tried editing /etc/network/interfaces and I forced the desired netmask, but as soon as I restarted the interfaces it changed it back to the default value.
When I used ifconfig the netmask that I gave survived the interface restart but it was reset as soon as I rebooted the machine.
Is there a way to force an "illegal" netmask on an interface?