DHCP Server

[ziggyboi]

Hi! I have modem/router box from my ISP that I have to use. It however plugs into a switch distibutes the internet around the house and have APs for wifi. I want to move my DHCP server off of the ISP provided box as it is pretty bad. There is no option to speicify another DHCP server there is only one to turn it on and off. If I turned it off and setup something else on my home server would it "broadcast" itself as a DHCP server ? Would i need to change the default gateway of my APs to the IP of that machine ? Also could anyone recommend a good DHCP server (preferably something I can dockerise)

[Eigenvektor]

You shouldn't need to do anything other than turn off the DHCP on the ISP's router and then turn it on in another router or e.g. a small machine with Linux on it (say RasPi) (and configure it, obviously, by specifying an IP range, DNS server IPs and the default gateway IP)

 

You shouldn't need to change the default gateway or IP anywhere else, that's the whole point of a DHCP server. If a client is set to automatic it'll send a broadcast asking for an IP, and the DHCP server will hand it an IP, DNS server and default gateway. So you only need to configure these things on the DHCP itself.

 

And the default gateway itself shouldn't change, that's still going to be the IP of the router that's connected to the internet (i.e. the gateway that leads to the internet)

[Falcon1986]

3 hours ago, ziggyboi said:

There is no option to speicify another DHCP server there is only one to turn it on and off.

So this is the only function that can be disabled? Not full IP passthrough or bridge mode?

 

What is the make/model of your ISP gateway?

 

3 hours ago, ziggyboi said:

I want to move my DHCP server off of the ISP provided box as it is pretty bad.

What does this mean? DHCP isn't too complex for an ISP device to run. Are you associating poor connectivity with the DHCP server on the ISP device?

 

3 hours ago, ziggyboi said:

Would i need to change the default gateway of my APs to the IP of that machine ? Also could anyone recommend a good DHCP server (preferably something I can dockerise)

PiHole or AdGuard Home. Both have a local DHCP server that can be turned on separately from the local DNS filter.

[ziggyboi]

Thank you for your reply

 

On 11/18/2023 at 1:22 PM, Falcon1986 said:

So this is the only function that can be disabled? Not full IP passthrough or bridge mode?

 

What is the make/model of your ISP gateway?

 

There are no IP passthrough or bridge DHCP can only be enabled or disabled

On 11/18/2023 at 1:22 PM, Falcon1986 said:

What does this mean? DHCP isn't too complex for an ISP device to run. Are you associating poor connectivity with the DHCP server on the ISP device?

I have quite a lot of IoT devices and it was recomended on smart home communities that DHCP should be moved off the router to improve connectivity of the IoT devices my regular internet and wifi work just fine.

 

On 11/18/2023 at 1:22 PM, Falcon1986 said:

PiHole or AdGuard Home. Both have a local DHCP server that can be turned on separately from the local DNS filter.

As a matterof fact I also wanted to change my DNS server which is blocked by my ISP would it be possible then to set up this DHCP server to use a DNS of my choosing ?

 

Also this might seem like a silly question but how would the machine running the DHCP server get an IP address ?

[ziggyboi]

Thank you for your reply 

On 11/18/2023 at 10:01 AM, Eigenvektor said:

You shouldn't need to do anything other than turn off the DHCP on the ISP's router and then turn it on in another router or e.g. a small machine with Linux on it (say RasPi) (and configure it, obviously, by specifying an IP range, DNS server IPs and the default gateway IP)

 

You shouldn't need to change the default gateway or IP anywhere else, that's the whole point of a DHCP server. If a client is set to automatic it'll send a broadcast asking for an IP, and the DHCP server will hand it an IP, DNS server and default gateway. So you only need to configure these things on the DHCP itself.

 

And the default gateway itself shouldn't change, that's still going to be the IP of the router that's connected to the internet (i.e. the gateway that leads to the internet)

While brainstorming for this I asked chatgpt and i recommended somehing called a double NAT setup where I would change the gateway on my APs setup eveything I want to on the linux server and then passthrough the connection to the gateway

[Falcon1986]

45 minutes ago, ziggyboi said:

I have quite a lot of IoT devices and it was recomended on smart home communities that DHCP should be moved off the router to improve connectivity of the IoT devices…

Never heard of this. How is this supposed to help?

 

Best practice recommendations now is to put all IoT devices on their own VLAN, with firewall rules to limit access to other VLANs. These devices will be on another network with its own DHCP server and full use of the private subnet of IPs if that’s what you want. In this way, they’re not competing for LAN IPs of your non-IoT VLAN.

 

45 minutes ago, ziggyboi said:

As a matterof fact I also wanted to change my DNS server which is blocked by my ISP would it be possible then to set up this DHCP server to use a DNS of my choosing ?

If your ISP’s gateway/router does not allow you to select your own DNS, you can use PiHole or AGH to do this for your clients.

 

Please note that PiHole and AGH are primarily local DNS solutions. The ability to run a DHCP server on them is just another feature that has to be turned on, since most people might never use it.

 

Personally, while I’ve gotten AGH to recognize clients from different VLANs, I’ve never used its DHCP server. IIRC, only one can be run.

 

45 minutes ago, ziggyboi said:

Also this might seem like a silly question but how would the machine running the DHCP server get an IP address ?

You assign its network interface a static LAN IP address outside of the DHCP pool.

 

42 minutes ago, ziggyboi said:

While brainstorming for this I asked chatgpt and i recommended somehing called a double NAT setup where I would change the gateway on my APs setup eveything I want to on the linux server and then passthrough the connection to the gateway

Don’t understand.

[Eigenvektor]

3 hours ago, ziggyboi said:

While brainstorming for this I asked chatgpt and i recommended somehing called a double NAT setup where I would change the gateway on my APs setup eveything I want to on the linux server and then passthrough the connection to the gateway

Double NAT is something you typically want to avoid.

 

Ultimately the data will have to go through the ISP's modem/router. Adding another system in between is unlikely to improve things.

 

You can setup e.g. a Pi-hole to serve as both your DHCP server and as a caching DNS server. With the benefit that it'll also help block some ads. I run it as a Docker Container on a small, low power Debian machine.

 

Your should be able to set whatever you want as the forwarding DNS server, but if your ISP blocks requests to other DNS servers, you'll be limited to whatever they allow.