Convert a DHCP server only sitting in the same subnet

Xarsage · 2022-01-21T11:33:18.105Z

Hello I have both GL-AR300M and GL-AR750 they both are great mini travel router.

Currently my existing devices:
internet > fiber modem (192.168.1.1) > wireless router (pppoe with VLAN 500, dhcp, 192.168.43.1) > access point (192.168.43.2)

My existing wireless router or access point have issue with DHCP they are limited to 2 days lease time and they unable to handle to busy renewal ip address, either one of them if I enable it will hang. Perhaps due to many smarthome devices (IoT, IP cameras).

So I wanted to use the one of GL-iNet, either GL-AR300M or GL-AR750 to convert as DHCP server and connect it eithe in my wireless router or access point, within same subnet and serve with following and issue the device with information:

Gateway: 192.168.43.1
Subnet: 255.255.255.0
DNS1: 8.8.8.8
DNS2: 8.8.4.4

How to configure the DHCP server ?

wcs2228 · 2022-01-21T22:39:19.499Z

Disable DHCP on your wireless router and set its Static IP to 192.168.43.1. Set access point Static IP to 192.168.43.2.

Configure your GL.iNet device in Router network mode with Static IP 192.168,43,3 and DCHP range 192.168.43.100-192.168.43.199 (for up to 100 IP’s) using MORE SETTNGS → LAN IP. Connect one LAN port to your wireless router, but do NOT connect the WAN side to anything (no wifi, no cable, no tethering, no 3G/4G modem).

If you want to manually set the lease time, you can use LuCI → Network → Interfaces → Edit LAN → DHCP Server.

Xarsage · 2022-01-22T04:35:50.841Z

Hi thanks for the reply,

I did this the devices connected it will given the IP address as follow:
Gateway: 192.168.43.3 to the GL.iNet not to my wireless router 192.168.43.1.

That’s way I puzzed no choice to use the GL.iNet as NAT to issue the IP addrress, Gateway and DNS1, DNS2. I can not find the DHCP GL.iNet with DHCP server configuration specificly for the pointed gateway.

The pointed gateway GL.iNet recognized as itself.

robotluo · 2022-01-22T06:57:56.055Z

You can try the following steps

Disable the DHCP service on the Wireless router
Enable the AR750 to work in accesspoint mode and set the static IP address 192.168.43.2
Run the following command to modify the DHCP Settings of the AR750

uci set dhcp.lan.ignore='0'
uci commit dhcp
/etc/init.d/dnsmasq restart

I have not actually tested the above steps. If there are other problems, I will continue to provide support.

wcs2228 · 2022-01-22T15:50:46.615Z

I forgot about the default gateway.

You can try going to LuCI → Network → Interfaces → Edit LAN → DHCP Server → Advanced Settings, then enter the following:

3,192.168.43.1

Click the Save button, then Save & Apply button. Reboot for good measure.

Xarsage · 2022-01-23T08:11:22.621Z

The sample there showing "6,192.168.2.1,192.168.2.2 " what “6” means? and yours what is “3” mean? How can I do more understand on this DHCP-Options settings?

I configured as:

3,192.168.43.1
6,8.8.8.8,8.8.4.4

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And the result is:

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At this point I decided to set my GL.iNet to “192.168.43.5”.
It seem these configuration is working. But I would like to know more understand where to configure DHCP-Option above, I been looking at https://linux.die.net/man/8/dnsmasq. I still puzzed.

I would to know how to set the DHCP reservation with “permanent” lease time given from GL.iNet? Is it “infinite”?

Like this sample DHCP Server with DHCP reservation permanent lease time from my wireless router:

There are few places I found related to DHCP, but I still no idea what is the correlation within outside and inside from luci.

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Xarsage · 2022-01-23T08:27:04.185Z

Hi do you know how to import or export list of static leases?

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wcs2228 · 2022-01-23T16:10:33.415Z

Xarsage:

The sample there showing "6,192.168.2.1,192.168.2.2 " what “6” means? and yours what is “3” mean? How can I do more understand on this DHCP-Options settings?

The following URL has description of DHCP, including all the DHCP options:

en.wikipedia.org

Dynamic Host Configuration Protocol

The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on Internet Protocol (IP) networks for automatically assigning IP addresses and other communication parameters to devices connected to the network using a client–server architecture. The technology eliminates the need for individually configuring network devices manually, and consists of two network components, a centrally installed network DHCP server and client instances of the protocol stack on each computer ...

If you use the GL-AR750S as the default gateway, then I think all external traffic will have to hit that device first, instead of going directly to your wireless router.

Xarsage:

I would to know how to set the DHCP reservation with “permanent” lease time given from GL.iNet? Is it “infinite”?

You can use Static IPs, or set DHCP Lease time to 100000h (which is >10 years) or even higher.

Xarsage:

There are few places I found related to DHCP, but I still no idea what is the correlation within outside and inside from luci.

Both the GL.iNet UI and the LuCI UI are really front-ends to the OpenWrt commands and API, so both should show the same settings. GL.iNet developed their UI to be much friendlier and simpler to use for the majority of owners, vs the much more detailed and complicated LuCI UI developed by the OpenWrt/LEDE project. I use the GL.iNet UI for basic functions and only use the LuCI UI if not available.

wcs2228 · 2022-01-23T16:22:36.797Z

I think you can add the static IP’s for MAC addresses in the /etc/ethers file:

linux.die.net

ethers(5) - Linux man page

/etc/ethers contains 48 bit Ethernet addresses and their corresponding IP numbers, one line for each IP number: Ethernet-address IP-number The two items ...

EDIT: Disregard this because /etc/ethers is not used to issue static IP’s.

Xarsage · 2022-01-24T01:27:48.141Z

Thanks, but “infinite” will assign as permanent.

I tried to register about 140 IP addresses and trying to registering them into “Static IP Address Binding” in luci (Network > DHCP and DNS > Static Leases) based on my specific IP ranges and categories, but it seem the devices stop issuing IP address and devices can’t get any IP address, in my “cmd” it said “unable to contact your DHCP server. Request has timed out”. I’m not sure if I registered them to many or something else.

wcs2228 · 2022-01-24T03:19:17.289Z

What is the Starting and Ending IP’s in your DHCP range?

Are all the Static IP’s within the DHCP range?

Xarsage · 2022-01-26T09:49:49.637Z

x.6 to x.239
Yes I wanted to assigned all static IP within the DHCP range

wcs2228 · 2022-01-26T15:23:31.329Z

If things work with only a few static IP addresses, then there may be a limit on how many can be added.