Static IP address of 255.255.255.255

Question

I live in a house with a couple of housemates and I manage our internet connection. When looking in the admin panel of the router I saw that one device has set its IP mode to static and the console shows the IP address as 255.255.255.255. Judging by the host name it seems to be an iPhone.

Which seemed weird so I went to search about that, I did find that this IP address is reserved for broadcasting to all devices in the network but I couldn't find any information if I need that function, or what the impact of this static IP is.

Is there a reason to change that IP address to something in the usual range?

Solution

255.255.255.255 represents the local broadcast address, which is only propagated within the network. This broadcast data cannot cross routers by default. That is, it is a restricted broadcast address. For the local host, this address refers to all hosts in the network segment (same broadcast domain).

Therefore, this address cannot be used for communication. And it’s necessary for you to change its IP address to the normal range.

You can set the way the device gets IP to use DHCP. If you still want to use static configuration, make sure that the manually configured address is not the same as the IP of other devices in the wireless network.

Comments

[dirkt]

You are sure this is the IP address, and not the netmask? If it is indeed the IP address, and this particular router doesn't reserve this value for something special (like "ignore this device"), I'd say this is a misconfiguration.

[Bob]

In the list of connected devices every device that have IP Mode "DHCP" are like 192.168.2.*, except for this one device that has IP Mode "Static". And has 255.255.255.255 listed as its IP address.

[dirkt]

Then it's possible that your router doesn't know the address, because it hasn't given out the address, and so 255.255.255.255 means "I don't know". Details depend on your brand and model of router, but even knowing these, someone who actually owns such a router would likely have to experiment to find out if this is the case, or not.

[Bob]

I see, and since 255 is the broadcast address could that imply that the packets to this device get send to every device on the network?

[dirkt]

I have no idea what would happen if there was a device with an actual address of 255.255.255.255 in the network. Probably fun things. I doubt it would work properly, though. And most OS should prevent you from assigning such an address in the first place.

[Bob]

Well, I don't mean it has the actual address. If my router lists it as 255 and 255 is the address that is for broadcasting to every device I reconnened that maybe to get packets to the device with an unknown IP address the router would just broadcast it everywhere, and list it as 255 in the console since that is where it will send packets for that device.

[Darren]

I would expect that if the iPhone in question really did have that IP address configured, it wouldn't be able to use the wifi network as it's not on the correct subnet. Do any of your housemates experience such a problem?