DHCP Limit Help / dnsmasq

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LighthammerX

Occasional Visitor
Greetings,

I'm running an ASUS AC-3100 with the current Asuswrt-Merlin firmware.

I'd like to be able to up the DHCP Limit probably up to the maximum. I keep a pretty firm grip on my IP assignments and I know the scope of what I do is probably FAR outside what the average user is going to need/do, so making a request to increase the DHCP limit is probably silly (though, I could probably live with the limit being doubled from 64 to 128).

A primary reason for my need is the fact I've added *A LOT* of smart devices to my home. I've probably doubled my IP assignment needs from this alone. I've moved things like Lightbulbs to the DHCP, but being the control freak I am when it comes to network management, I don't really like this setup. I still prefer being able to look at a given light and know where it is on my network.

In doing some research on this forum, it looks like doing a dnsmasq might be best for my usecase, but I'm not seeing a good walkthrough how to do this (this is new territory for me).

I wanted to see if someone could point me in the right direction of how to either increase the DHCP limit myself or to setup and manager a dnsmasq.

Thanks in advance.
 

eibgrad

Very Senior Member
When you create a static lease in the GUI, all the router does is create a dhcp-host record in the underlying DNSMasq config file, which you can readily dump w/ the following command using SSH.

Code:
grep dhcp-host= /tmp/etc/dnsmasq.conf

Just use that as a model for creating your own dhcp-host records and adding them via a DNSMasq custom config file.

And btw, while I understand the need to know about these IOT devices, there's no need to assign them static leases (at least not all of them). You can simply create dhcp-host records that *only* specify the hostname and MAC address, w/o the need for a specific IP assignment. The device just grabs an IP from the DHCP pool, but it still shows up on most device lists since it has a dhcp-host record. I just can't see creating a static lease for a device that has no addressable interface by which you can access it.
 
Last edited:

eusagc

Occasional Visitor
If you have amtm/entware running, you can also try installing the YazDHCP addon. On my AC88U at least, the static assignment has been increased from 64 (default) to 162 (dunno how/where this limit is set). It also lets you import/export CSV lists, very convenient if you've got a lot of static stuff.

And btw, while I understand the need to know about these IOT devices, there's no need to assign them static leases (at least not all of them). (SNIP) I just can't see creating a static lease for a device that has no addressable interface by which you can access it.
Word! In my case, I put all my IoT stuff into a guest SSID, and assign a DHCP pool range for this. I don't care what IPs they get, since, as eibgrad above, they got no access interface anyway. Exceptions for me are IP cams, because of ONVIF/RTSP.
 

Jack Yaz

Part of the Furniture
If you have amtm/entware running, you can also try installing the YazDHCP addon. On my AC88U at least, the static assignment has been increased from 64 (default) to 162 (dunno how/where this limit is set). It also lets you import/export CSV lists, very convenient if you've got a lot of static stuff.
It's calculated using 6kb (to stay below addon api save limit) divided by the average length of your reservations. A greater number of reservations is also possible by chopping out the subnet when saving (i.e. A /24 is assumed and only the final octet is passed via the api)
 

eusagc

Occasional Visitor
A greater number of reservations is also possible by chopping out the subnet when saving (i.e. A /24 is assumed and only the final octet is passed via the api)
Thanks for this info. I'll do it like this in my static list.
 

LighthammerX

Occasional Visitor
It's calculated using 6kb (to stay below addon api save limit) divided by the average length of your reservations. A greater number of reservations is also possible by chopping out the subnet when saving (i.e. A /24 is assumed and only the final octet is passed via the api)

Thats an interesting factoid.

Thanks for the guidance all, especially from eibgrad.
 

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