RT-N66U in AP mode running merlin

[seanspicer]

I have an ASUS RT-N66U running in AccessPoint mode wired to an Asus DSL-N66U operating as my internet router & DHCP server. This works really well; the same wireless SSID's are configured on both devices and wireless clients in the house seamlessly roam between them.

I would like more control over name resolution on my LAN & am hoping asuswrt-merlin can give me this. However, it is only supported to be installed on the RT-N66U so i would like to know if it will continue to operate seamlessly in access point mode once upgraded.

Can anyone advise ?

 

[ColinTaylor]

There shouldn't be any problem with Merlin running in AP mode, particularly as most of the routers functionality is disabled in that mode.

I don't see how changing the firmware will help in name resolution as that will still be done by the DSL-N66U.

Of course you could ask your boss, Donald. He seems to think he knows more than anyone else.

 

[MichaelCG]

Agree with previous poster. The RT-N66U will function just the same with Merlin as it does with the Asus firmware. I ran one of my RT-N66U in AP mode for a couple of years. Just be aware the DNS and DHCP features will most likely be disabled since it is in AP mode. I don't remember if you can turn those back on manually or not when in AP mode.

If you are wanting better control of DNS, you will be better served in the long term by moving to a dedicated router that you can modify the firmware/settings on. Keep the DSL modem as just a modem....not a combo modem/router/wifi.

 

[thelonelycoder]

Of course you could ask your boss, Donald. He seems to think he knows more than anyone else.

Just be aware the DNS and DHCP features will most likely be disabled since it is in AP mode. I don't remember if you can turn those back on manually or not when in AP mode.

SAD, VERY SAD NEWS.
THE MASQ IS DISABLED, SAD. BAD MERLINQUIN.

 

[ColinTaylor]

SAD, VERY SAD NEWS.
THE MASQ IS DISABLED, SAD. BAD MERLINQUIN.

I have no idea what that means - so I'll call it FAKE NEWS!

 

[seanspicer]

thanks very much everyone for your advice. I am now thinking of relegating the DSL-N66U to just an internet router and wifi access-point, so i can have more control. I think the steps will be:
- take the RT-N66U out of AP mode
- move the DHCP service from the DSL-N66U to the RT-N66U
- apply ASUSWRT-Merlin to RT-N66U

Any tips ? The network connection between the 2 devices uses the WAN port on the RT-N66U. Should this remain as is ?

 

[ColinTaylor]

Tricky... If you take the RT- out of AP mode (into router mode) then you have created a subnet that is separate from the one on the DSL-. That means you have a double-NAT situation that people try to avoid for various reasons.

At this point it's probably best if you provide some more detail on what you are trying to achieve. You say you want "more control over name resolution", but what exactly is it that you can't do on the DSL- that you think Merlins firmware can?

 

[seanspicer]

@ColinTaylor - thanks

Simply, I want to run a DNS service on my home LAN to resolve local hostnames.

Trying to get name resolution working correctly across Microsoft Windows, Apple macOS & Linux systems is proving to be a real challenge. In particular, i am struggling to get the Linux Ubuntu hostname to resolve on other devices, included iOS iPhones & iPads. From reading here, it seems that once Merlin is installed, i can use dnsmasq to achieve this.

Here is a visualisation of my setup at the moment.

 

[seanspicer]

... and also i have just noticed a large difference between the 2 devices:
- DSL-N66U : 60MB RAM total (49MB used)
- RT-N66U : 234MB RAM (50MB used)

so the RT appears the more capable device and has loads of RAM free; i would like to give it a little more to do

 

[ColinTaylor]

OK I see your problem.

The more I think about this, the more problems I see with what you were proposing (putting the RT- in router mode). Having 2 different subnets will present problems for devices that "roam" between the two routers and will just exacerbate you name resolution issues.

The path of least resistance would probably be to leave the RT- in access point mode but to manually set it up as the DHCP & DNS server (both are handled by dnsmasq), and disable DHCP/DNS on the DSL-.

The downside of that is that you will have to maintain the DHCP/DNS configurations by manually editing the config files rather than through the GUI. Are you happy to do it that way?

 

[seanspicer]

That configuration sounds perfect, and yes I am happy to maintain manually.

How do I enable just those functions in AP mode then ?

 

[ColinTaylor]

OK I've just dug out my old RT-N66U and set it up that way and it looks like it will work.

It's probably best if we go through this slowly one step at a time.

So the first thing to do is flash the RT-N66U with Merlin's latest firmware which is currently 380.66_6

http://www.mediafire.com/file/ytj8428eykqzu0k/RT-N66U_380.66_6.zip

After flashing, unplug the WAN cable (your PC should be connected directly to one its LAN ports) and perform a factory reset. It should come back with an IP address of 192.168.1.1

Go through the Manual (offline) setup procedure accepting the defaults for router mode even though the WAN is disconnected.

You should now have access to all of the routers' menu screens.

Go to Administration > System and choose to Format JFFS, Enable JFFS custom scripts, and Enable SSH for LAN only. Apply and then click the Reboot button.

Wait for the router to come back.

 

[ColinTaylor]

Now it gets interesting .

You now have to decide what IP range you will be using - Your DSL- is currently using 192.168.0.1 so I'll assume that's what you want. So you have to go to LAN > LAN IP > IP Address and put in 192.168.0.1 then Apply.

When changing the devices IP address you'll probably have to close and re-open your browser to log back in.

Go to WAN > Internet Connection >

Connect to DNS Server automatically = No
DNS Server1 & 2 = Your ISP's DNS servers (or whatever external DNS you use)​

Apply.

Go to LAN > DHCP Server >

IP Pool Starting Address = 192.168.0.10
DNS Server 1 = 192.168.0.2 (this is the address we will eventually assign to this AP)
Advertise router's IP... = No
Enable Manual Assignment = Yes and then enter at least one manual entry in the list below.​

Apply.

These settings will create our default dnsmasq files which we will have to manually edit from here on if we want to make changes, so it's worth getting it right now.

 

[ColinTaylor]

Log onto the RT-N66U using SSH.

You should find the following 4 files:

/etc/dnsmasq.conf
/etc/ethers
/etc /hosts.dnsmasq (there is no space between etc and / but Clouflare won't let me enter it )
/tmp/resolv.conf

Copy all of these files to the /jffs directory. These are the files we need to preserve when we switch to AP mode.

/jffs/ethers and /jffs/hosts.dnsmasq now contain the information you entered in the Manual Assignment list. You will need to edit these if you want to add or remove hosts from DHCP/DNS. Changes will not show up in the GUI if you ever switch back from AP to router mode.

/jffs/resolv.conf should contain only your external (ISP's) DNS servers and nothing else.

 

[ColinTaylor]

OK. So now we have all the files we need. We just need to switch DHCP/DNS servers.

Go to Administration > Operation Mode and choose Access Point mode then Apply.

Get LAN IP Automatically = No
IP Address = 192.168.0.2
Subnet Mask = 255.255.255.0
Default Gateway = 192.168.0.1

Next, Apply. Plug the WAN cable back in and then wait for it to reboot.

SSH into the RT-N66U at 192.168.0.2 and create the /jffs/scripts/services-start script below:

#!/bin/sh
cp /jffs/dnsmasq.conf /etc
cp /jffs/ethers /etc
cp /jffs/hosts.dnsmasq /etc
cp /jffs/resolv.conf /tmp
ln -sf /rom/etc/resolv.conf /etc/resolv.conf
dnsmasq --log-async

Then make it executable:

chmod 777 /jffs/scripts/services-start

Open another broswer tab and log into the DSL-N66U (192.168.0.1) and disable DHCP: LAN > DHCP Server > Enable the DHCP Server = No. Apply

Then reboot the AP (RT-N66U) to start up our new DHCP/DNS servers.

After the AP has rebooted restart all of your client devices to pick up the changes.

That's it. Finished.

 

[seanspicer]

Colin

Wow thanks for this detailed guide. I really appreciate your efforts working through this. I will start following your instructions and then wait for the next thrilling instalment


S.

 

[thelonelycoder]

Colin

Wow thanks for this detailed guide. I really appreciate your efforts working through this. I will start following your instructions and then wait for the next thrilling instalment


S.

This reads like an interesting book, and it's not a novel...

 

[ColinTaylor]

OK guys I've updated post #15 with the final step. Please report any errors or changes to make it clearer/simpler/better.

EDIT: I've noticed (as suspected) that making certain changes to the AP through the GUI (like modifying Samba) will kill the dnsmasq process. This is normal behaviour. So this is something to remember, and the solution is to reboot the AP after you've finished making your changes.

If anyone can think of a way of avoiding a reboot then please let us know.

I do wonder whether there's a way of re-enabling both the dnsmasq process and the GUI page (in AP mode) by clever manipulation of NVRAM variables. Anyone care to try?

 

[seanspicer]

Colin

All instructions followed. Specific feedback:
1) #15 : the first time I followed post #15, after the final reboot all the files I created in /jffs had been deleted ! I wondered whether this was because I had logged into the RT GUI during implementing #15 and used the GUI-reboot-button. On repeating the whole process, I was careful not to login to the GUI and used the power button on the RT. the files have now persisted ....
2) #13 : I created ALL manual DHCP assignments active on the DSL-N66U
3) #14 : 2nd time around, I took a copy of all these files locally on my laptop, just in case I lost them again

Anyway, its all mostly working now so thank you very much for your assistance

I do have one final niggle, which I think is more related to DNS/DHCP config than ASUS router config. nslookup is working as expected, but resolution of a name (i.e. in a browser or ping command) sometime requires a '.' appended to the name. i.e.:

- ping macbook = FAILS
- ping macbook. = SUCCESS

do you know why this is ?

 

[ColinTaylor]

Hi @seanspicer

I'm glad to hear that you got it working (and you could make sense of my instructions).

Regards point 1) - I think I experienced the same thing early in my experiments. I wasn't sure what caused it as I think /jffs should only be wiped if the option is selected in the GUI or doing a factory reset. So when I wrote the final instructions I went through it verbatim and the problem didn't reoccur - go figure.

Point 3) - I thought of suggesting that, but didn't want to make the instructions overly complicated unnecessarily. Perhaps I should have.

Regarding your DNS issue - I've seen this before and it's a configuration issue (usually on the client side). Unfortunately it was a long time ago and I can't remember the specifics. One clue is that using "mackbook." forces a lookup on the DNS server (the Asus). Using a short name "mackbook", particularly on Windows clients, can use different resolution priorities like NetBIOS or appending local DNS suffixes.

If you can try and narrow down what does and doesn't work (is it only certain names, is only from certain PC's) we might be able to get to the cause.