topic Re: LAN IP Setup - Address Reservation list in Broadband

LAN IP Setup - Address Reservation list

THX1138 — Thu, 29 May 2025 09:38:48 GMT

Hi All

Under the Advanced, LAN IP Setup, I have used the Address Reservation list to restrict which devices can access the Sky SR203 hub.

I have always wondered if the ‘Device Name’ field had any impact on the Address Reservation list, or is it simply a free text field that you can put anything in? Is the MAC Address the only unique identifier of a device?

I have also noticed from time to time a couple of anomalies, which I can’t figure out under the ‘Devices connected to your home network’ display on the hubs home page:

The Device Name is sometimes shown as UNKNOWN
The Device Name is not the same name as entered in the Address Reservation list – instead it’s the name used internally within the device

Will the devices actual name e.g., LC45679G4, always override the name I have entered in the Address Reservation list e.g., Bobs-HP-Laptop, when viewing the home page Devices connected to your home network’ display?

I have a new replacement hub on its way and want to take the opportunity to tidy up the Address Reservation list and use more meaningful device names in the list if possible. I’m going to input everything manually from scratch, rather than do a backup of the faulty hub and upload this into the new hub – which could bring across hidden defects.

Many thanks

Re: LAN IP Setup - Address Reservation list

Deb3000 — Thu, 29 May 2025 09:50:55 GMT

Address reservations should be set against the MAC address. Sky may allow you to use device names but it’s sloppy because the name is not unique* and some devices do not advertise their given name anyway, (as you have seen).

*Two devices with the same name would cause chaos and probably bring the network to a halt. It also has nothing to do with security as anyone can still generate a valid IP address on your network.

Re: LAN IP Setup - Address Reservation list

THX1138 — Thu, 29 May 2025 10:51:57 GMT

Thanks @Deb3000

That's good, and as I had hoped - the MAC Address is key and not the Device Name.

Regards security, in addition to the using the Address Reservation list to assign dedicated IP addresses to each of my 24 listed devices, I also set an IP Starting Address and an IP Ending Address range to control how many IP addresses the hub can give out – in this case it can only give our 24 IP address to match the 24 devices* in the Address Reservation list. Makes it difficult for anyone else’s device, not on the list, from being able to generate an IP address.

*The Sky Hub is device 0 which is not in the list.

Re: LAN IP Setup - Address Reservation list

Deb3000 — Thu, 29 May 2025 11:23:21 GMT

That does not limit the address range available, a custom subnet mask does that. For example 255.255.255.0 would be addresses 0 to 255 in the same network. 255.255.255.240 would chop the address range in two, with one network using 0 to 128 and the other using 129 to 255. I doubt whether a domestic grade router would allow a custom subnet mask.

Even then, nothing to stop me setting a static address from my end or I could just hijack one of the existing device IPs. And if I did, do you seriously think I'd be daft enough to leave a log entry showing I was there?

Up to you how you set it up but beware, address reservation is nothing to do with security!

And by device 0, I assume you mean 192.168.0.0 That's the network address not a device address. The router will be something between 1 and 254, probably 192.168.0.1 (0 and 255 are THE reserved addresses, one being the network identifier and the other the universal broadcast address. They can never be assigned to a device).

Re: LAN IP Setup - Address Reservation list

Deb3000 — Thu, 29 May 2025 13:19:51 GMT

Surprised nobody else noticed I got that wrong. Example should have been 255.255.255.128!

You might be able to reduce the effective network size with a VLAN but it's still not really a security thing. (No idea if the latest Sky router can do VLANs, as I don't use one).

Re: LAN IP Setup - Address Reservation list

JimM1 — Thu, 29 May 2025 13:39:01 GMT

@Deb3000 And yes they do not have Vlan's. And your subnet?

Re: LAN IP Setup - Address Reservation list

Deb3000 — Thu, 29 May 2025 13:57:37 GMT

@JimM1 Of course they don't.

Hope you didn't get into trouble the other day? I noticed you were notable by your absence the day after my little tete-a-tete with the 'uber-watch'.

Re: LAN IP Setup - Address Reservation list

JimM1 — Thu, 29 May 2025 14:19:55 GMT

@Deb3000 Which day and which question, refresh my old memory? Been good so far so no problems!

Re: LAN IP Setup - Address Reservation list

Deb3000 — Thu, 29 May 2025 14:50:17 GMT

Oops....reply gone missing again! You'd remember if it had, so lets just leave at that.

Was thinking of coming back to Sky as a customer but not now.