Dual booting Linux and Windows and a static dhcp lease on a hardware firewall

Let’s say that you are using a hardware firewall. It may be Ipfire or Pfsense box or something else. You have a setup, which focuses on security and hence you have given each and every machine a static lease from the firewall’s dhcp server. The previous means that you might have a setup where dhcp range is small and occupied by your machines. Also, since you have given each machine a static lease you also know their local ip addresses and you are also able to tell all the mac addresses of the devices in your network.

At this point you should be set with a reasonably secure firewall. But there might be a problem ahead  if you are dual booting your main Linux system with (at least) Windows 10. The example below highlights the issue more clearly.

Let’s say that your Linux system has box_1 as a hostname.

Let’s further assume that your Windows 10 system  has box_x as a hostname.

If you were on Linux system when you did your firewall configuration and static leases then your static lease list says that the hostname of your device is box_1. At this point you should have a network connection. However, when you boot to Windows 10 you should also have a network connection but this time the hostname of your device changes from box_1 to box_x.

The problem that actually seems to follow is that Windows 10 takes over Linux within the hardware firewall’s static lease. Next time your boot to Linux the hostname in firewall’s static lease list seems to stay in box_x and thus fail to change to box_1. The result of the previous is that you will have no Internet connection on the Linux side. To solve this issue you need to remove your computers static lease and give your dhcp more range.

For example. If you have five devices on your network then the range should be something like: for the dual booting to work properly. You can of course bind all other devices statically – given that they do not switch hostnames. Alternative – and more simple- solution is to use unified hostnames on your device’s opetation systems. The trick is simple: If the hostname does not change then the hardware firewall should have no problem in giving the device an access to online resouces – regardless of the operation system. Further clarification: Your hardware firewall actually might think that there are two devices, due to different hostnames, and it gets confused since the mac address remains the same.

Note. I recommend using something else as than as your firewall’s gateway ip. is the default in almost all firewall and router solutions and it remains the first thing to try when somebody tries to break in to your network. Change your gateway and dhcp server pool to something more unique instead.