topic Re: Smart Hub - Can I change DHCP/DNS settings for LAN? in Archived Posts

Smart Hub - Can I change DHCP/DNS settings for LAN?

Hi_ImTemmy — Sun, 19 Sep 2021 07:50:12 GMT

Hello,

I have a EE Smart HUB.

I want to set DNS settings for devices on my LAN (Not for the WAN / Internet connection - that's a different thing entirely) Other routers would offer options like this:

However in the Smart HUB I can only find:

Is there any way of setting static DNS for DHCP?

Thanks.

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

Jon_K — Sun, 19 Sep 2021 11:09:30 GMT

Hi @Hi_ImTemmy.

Hopefully one of our community broadband experts will be along shortly to give you a definitive answer on this.

Jon

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

mikeliuk — Sun, 19 Sep 2021 12:14:22 GMT

Hi @Hi_ImTemmy ,

Does the below link help you locate this setting?

https://community.ee.co.uk/t5/Broadband-home-phone/Can-t-change-DNS-settings/td-p/1024742

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

Hi_ImTemmy — Sun, 19 Sep 2021 12:30:56 GMT

It does not.

As you can see in the Smart HUB Manager screen shot I am in IPv4 Configuration, and there is no setting for "DNS Servers: Auto to Off".

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

mikeliuk — Sun, 19 Sep 2021 13:33:59 GMT

I think I'm missing something obvious as I think that's supposed to be the device where it's easier to find.

The below is probably also a subtle mismatch.

https://community.ee.co.uk/t5/Broadband-home-phone/Change-DNS-on-Smart-Hub/td-p/724056

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

pip11 — Sun, 19 Sep 2021 14:16:01 GMT

@Hi_ImTemmy You have the Smart Router not Smart Hub. You cannot change DCHP/DNS settings.

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

XRaySpeX — Sun, 19 Sep 2021 18:13:23 GMT

@Hi_ImTemmy : Yes, you may change DNS settings. You have the Smart Hub not the Smart Router as alleged above. Your images show as much.

You can change your DNS to Manual on the Advanced / BB / Internet page & enter the 2 IPs of your preferred DNS - see near the bottom:

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

pip11 — Sun, 19 Sep 2021 20:01:59 GMT

@XRaySpeX My bad, I misread the OP's image from the hub.

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

XRaySpeX — Sun, 19 Sep 2021 21:53:06 GMT

@pip11 : You can also change the DNS on the EE Smart Router but at a diff place by going to Advanced > My Network > IPv4 Configuration & choosing Auto = "No" as shown below at foot:

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

Hi_ImTemmy — Mon, 20 Sep 2021 06:20:22 GMT

My understanding is those DNS settings are for the WAN, whereas I'm after DNS settings which are given to DHCP connected devices. Hence why other routers have DNS options in their DHCP settings.

I believe what I'm after can't be done with a Smart HUB.

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

XRaySpeX — Mon, 20 Sep 2021 12:50:03 GMT

There are no DNS settings just for the LAN. DNS works on the basis of "I may not know the answer but I know a man who does". The LAN points to the router, 192.168.1.254, as its DNS & the router in turn points to actual external DNS.

DNS really has nowt to do with DHCP other than it is passed on to DHCP-connected devices.

What are you actually trying to do?

Re: Smart Hub - Can I change DHCP/DNS settings for LAN?

mikeliuk — Mon, 20 Sep 2021 19:36:37 GMT

Hi @Hi_ImTemmy ,

You've made an interesting observation as my original belief was that consumer routers make no distinction between the DNS set for the router itself ("for the WAN") versus the DNS setting for the LAN.

I have three routers in production: Netgear MR110, Cisco/Linksys DD-WRT, and a Linksys OpenWRT router all of which have custom DNS settings. What I find, as shown below, is that the DHCP response returns the router as the DNS and forwards requests to the chosen DNS set in the router. The OpenWRT router documents this the most clearly with the label "DNS forwardings".

I suspect that the behaviour with your router in the DD-WRT screenshot will be the same that the DHCP request will specify the DNS as the router and will forward to the DNS set in the management page. I think it's likely you have a Linux server around so can run the below nmap command/script to see the DNS specified in the DHCP response. Obviously if you want to change the DNS on a per-server basis, you can do this in /etc/resolv.conf but I suspect you want to do it for many other non-server devices if you want it going out by DHCP.

[x@x ~]# for i in br{1..3}; do nmap --script broadcast-dhcp-discover -e $i; done
Starting Nmap 7.70 ( https://nmap.org ) at 2021-09-20 20:19 BST
Pre-scan script results:
| broadcast-dhcp-discover:
| Response 1 of 1:
| IP Offered: 192.168.X.149
| DHCP Message Type: DHCPOFFER
| Server Identifier: 192.168.X.254
| IP Address Lease Time: 2m00s
| Renewal Time Value: 1m00s
| Rebinding Time Value: 1m45s
| Subnet Mask: 255.255.255.0
| Broadcast Address: 192.168.X.255
| Domain Name Server: 192.168.X.254
|_ Router: 192.168.X.254
WARNING: No targets were specified, so 0 hosts scanned.
Nmap done: 0 IP addresses (0 hosts up) scanned in 2.78 seconds
Starting Nmap 7.70 ( https://nmap.org ) at 2021-09-20 20:19 BST
Pre-scan script results:
| broadcast-dhcp-discover:
| Response 1 of 1:
| IP Offered: 192.168.Y.249
| DHCP Message Type: DHCPOFFER
| Server Identifier: 192.168.Y.1
| IP Address Lease Time: 2m00s
| Renewal Time Value: 1m00s
| Rebinding Time Value: 1m45s
| Subnet Mask: 255.255.255.0
| Broadcast Address: 192.168.Y.255
| Router: 192.168.Y.1
| Domain Name Server: 192.168.Y.1
|_ Domain Name: lan
WARNING: No targets were specified, so 0 hosts scanned.
Nmap done: 0 IP addresses (0 hosts up) scanned in 3.43 seconds
Starting Nmap 7.70 ( https://nmap.org ) at 2021-09-20 20:20 BST
Pre-scan script results:
| broadcast-dhcp-discover:
| Response 1 of 1:
| IP Offered: 192.168.Z.69
| DHCP Message Type: DHCPOFFER
| Server Identifier: 192.168.Z.254
| IP Address Lease Time: 2m00s
| Renewal Time Value: 1m00s
| Rebinding Time Value: 1m45s
| Subnet Mask: 255.255.255.0
| Broadcast Address: 192.168.Z.255
| Router: 192.168.Z.254
| Domain Name: net
| Interface MTU: 1500
|_ Domain Name Server: 192.168.Z.254
WARNING: No targets were specified, so 0 hosts scanned.
Nmap done: 0 IP addresses (0 hosts up) scanned in 3.57 seconds