Smart Hub Plus ipv4 configuration

[David-A-James]

I've just moved to EE's FTTP from Plusnet's FTTC.

I'm trying to configure an (internal) ipv4 addess for the new Smart Hub Pkus to an IP address which is not in one of the private IP address ranges. This doesn't seem to be possible (Error message "The Hub IP address is not a valid privaye IP address") - is setting an IP address outside the private IP address ranges not allowed?

This is the way that I had my Plusnet router configured (this set up goes back many years through many ISPs back as far as Demon Internet).

[David-A-James]

By "non-private IPv4 address" I mean an address that isn't in the private IP address ranges (that is (per RFC1918) 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255, and 192.168.0.0 to 192.168.255.255).

For historical reasons, my internal network is running on a class C network that was assigned to me many years ago (and taken back during one of the times when there was a panic about exhaustion of the IPv4 address range).

You say "The LAN interface of your Plusnet/EE hub should never be assigned a public IP address" and, yes, I am aware that one should not do this, but I'm too lazy to change it (and I don't like changing things that aren't broken).

In practice, it doesn't cause any issues as it does not get out on to the Internet and I don't need to access any hosts that are on the Internet in that class C network.

I don't now want or need to configure DHCP on the hub as I have (as you say) a DHCP server on my local network (and that integrates with the DNS server on my local network}.

So, as I said in my reply of 07:56 PM, I believe I now have a working solution.

[bobpullen]

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@David-A-James wrote:

You say "The LAN interface of your Plusnet/EE hub should never be assigned a public IP address" and, yes, I am aware that one should not do this, but I'm too lazy to change it (and I don't like changing things that aren't broken).

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How curious. I have to say that mine and your definitions of 'broken' differ 😉

I wasn't expecting you to be referring to non-private IP's in the literal sense!

Glad to hear you've arrived at a solution that works for you however, to address your original question: -

... is setting an IP address outside the private IP address ranges not allowed?

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If it is then I'd warrant a guess that it's entirely unintended as the consumer BT/EE hubs are not designed to support No-NAT/routed public IP assignments.

I'm honestly surprised the Plusnet Hub allowed you to do this.

[David-A-James]

I can't find a way to quote bobpullen's reply, so ...

In this case, my definition of "broken" is "doesn't work". The setiup I have works now, and has worked for many years with several different ISPs (and on FTTC, ADSL-2, probably ADSL and quite possibly dial-up before that).

I've not said anything about no-NAT/routed public IP - for the avoidance of doubt, the Smart Hub Plus will be NATting my connections and the non-private IP addresses will not be getting out to the Internet.

If I were starting from scratch now (or in recent years, for some value of recent that isn't particularly recent) I'd not be using this set-up, but to convert my local DHCP server, my local DNS server, and the static IP addresses on all of my devices that have static IP addresses (and they have them for good reasons) is a reasonable amount of work, that it would be very easy to make errors whilst doing, and that doesn't get me any advantages.

At the moment, there don't appear to be any DNS entries for the particular class C block I am using, so even the possible problem of there being hosts out there that I'd not be able to access because they have addresses in the class C block I am using doesn't (fortunately and by pure chance) currently apply.

Reddit has a somewhat interesting (2 year old) thread on this at https://www.reddit.com/r/PFSENSE/comments/18h43st/do_i_need_to_use_rfc1918_address_spaces_for_my/

[WillKirk]

So in summary the OP is doing it wrong, knows he is doing it wrong, doesn’t want to stop doing it wrong and wants the new standard router provided to also allow him to do it wrong so he doesn’t have to stop doing it wrong.

The ‘right way’ you obviously know and are very knowledgeable about so I wouldn’t try to convince you otherwise, but the answer is: no. The private IP address ranges are used to allow standardisation behind the NAT so as to not potentially route traffic out onto a wider area network. So the router is set to use private IPs, not public ones in that sense.

Your intention does not seem to be to deliberately use public IPs to interface with the internet and instead do intend to use the NAT… so, as stated above. In relation to how LANs work in this scenario, you’re trying to work against it not with it… up to you.

[David-A-James]

I think I admit defeat ...

I can (as I have said in a post above) assign the IPv4 addtress I want to the EE Smart Hub Plus's internal (LAN) interface(s), I find that having done that I don't appear to be able to get port forwarding to work.

I've now put the Smart Hub Plus back to default settings (in the 192.168.1.0/8 network, and made some temporary changes to IPv4 addresses on the devices in the internal networkso that they can see the hub and it can see them), and now port forwarding appears to work.

So I guess I'm going to have to bite the bullet and change all my internal IP addresses ...