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Tutor

Re: RBR850 frequently issuing DNS REFUSED responses

How do you disable it after enabling it?   I notice that it's available outside network (WAN).

Message 26 of 43
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Apprentice

Re: RBR850 frequently issuing DNS REFUSED responses

I guess you could set the 

telnetd_enable=1 to 0 and do a nvram commit and reboot

Message 27 of 43
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Guru

Re: RBR850 frequently issuing DNS REFUSED responses

https://community.netgear.com/t5/Orbi-AX/Intermittent-DNS-lookup-failures-on-RBR850/td-p/1978111/jum...


@arildj wrote:

I guess you could set the 

telnetd_enable=1 to 0 and do a nvram commit and reboot


 


My Setup (Cable 900Mbps/50Mbps)>CAX80>XR450 v2.3.2.106(Router Mode)>RBK853 v3.2.11.2(AP Mode)
Additional NG HW: C7800/CM1100/CM1200/CM2000, Orbi CBK40, RBK853, R7800, R7960P,
EX7500/EX7700, XR450 and WNHDE111
Message 28 of 43
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Apprentice

Re: RBR850 frequently issuing DNS REFUSED responses

I have inspected a litle further and  with strace you could see tons of errormessages regarding read like this:

read(8, 0x166feda0, 272) = -1 EAGAIN (Resource temporarily unavailable)

 

where fd=8 is coming from the following call:

inotify_add_watch(8, "/tmp", IN_CLOSE_WRITE|IN_MOVED_TO) = 1

I guess the idea here was to watch for changes in resolve.conf and this might be a bug.

 

A lot of daemons logs to /tmp and making dnsmasq busy watching  filecloses in /tmp

which result in the DNS forward request being "refused"

 

A workaround that seems to do the trick is to move resolv.conf to a less busy directory, in my case I created /tmp/dns/resolve.conf

 

and launched from commandline:

/usr/sbin/dnsmasq -h -n -c 0 -N -i br* -r /tmp/dns/resolv.conf -u root

 

No dns-errors after 1 hour running so fare

Message 29 of 43
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Tutor

Re: RBR850 frequently issuing DNS REFUSED responses

@arildj @FURRYe38 Looks like you have signed up to be beta testers. As few of us are having these DNS issue, can you please forward the issue and above resolution to NG engineering? Hopefully they will take that into condieration in next foirmware update.

 

Thanks!

Message 30 of 43
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Apprentice

Re: RBR850 frequently issuing DNS REFUSED responses

Running without errors for 24 hours now, so this seems to have fixed it.

 

I will send the information to them, and request for a bugfix. Propably is the "-n" --no-poll  feature broken and the file-poll badly implementet.

Message 31 of 43
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Guru

Re: RBR850 frequently issuing DNS REFUSED responses

Any forum user experiencing problems with there NG products are encouraged to first and foremost make contact with NG support:

https://www.netgear.com/support/#

 

File a support ticket and let NG know about what you are experiencing. You can also try contacting a forum  moderator as well. Blanca_O, and Christian_R, ErnestTheGreat are my first moderators I try to contact.

Thank you. 


@Ace321 wrote:

Looks like you have signed up to be beta testers. As few of us are having these DNS issue, can you please forward the issue and above resolution to NG engineering? Hopefully they will take that into condieration in next foirmware update.

 

Thanks!


 


My Setup (Cable 900Mbps/50Mbps)>CAX80>XR450 v2.3.2.106(Router Mode)>RBK853 v3.2.11.2(AP Mode)
Additional NG HW: C7800/CM1100/CM1200/CM2000, Orbi CBK40, RBK853, R7800, R7960P,
EX7500/EX7700, XR450 and WNHDE111
Message 32 of 43
Highlighted
Tutor

Re: RBR850 frequently issuing DNS REFUSED responses

Still learning the implementation so far it looks like they run this software based on openwrt and everything is loaded into RAM (tmpfs) at boot from the image.    Which means you can't make persistent changes to the filesystem once loaded.

 

So, all if you have to do is reboot to revert changes made which is what I did to undo Telnet access.

Message 33 of 43
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Apprentice

Re: RBR850 frequently issuing DNS REFUSED responses

This is not correct, you could do a lot of changes which will remain after reboot.

 

nvram, overlay-filesystem ant more will not be erased.

 

/tmp is tmpfs and cleared each time

Message 34 of 43
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Tutor

Re: RBR850 frequently issuing DNS REFUSED responses


@arildj wrote:

This is not correct, you could do a lot of changes which will remain after reboot.

 

nvram, overlay-filesystem ant more will not be erased.

 

/tmp is tmpfs and cleared each time


 

Well that's good news - can you please walk me through how I can modify the parameters dnsmasq uses so that they persist each boot?

 

Cheer!

 

Message 35 of 43
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Apprentice

Re: RBR850 frequently issuing DNS REFUSED responses

Something like this will do:

 

copy /usr/sbin/dnsmasq to /overlay/upper/usr/sbin/orbi-dnsmasq 

make a file called dnsmasq in /overlay/upper/usr/sbin (this will hide the original dnsmasq from the running os) with the following lines:

 

#!/bin/sh
mkdir /tmp/dns
echo "nameserver 8.8.8.8" > /tmp/dns/resolv.conf
echo "nameserver 8.8.4.4" >> /tmp/dns/resolv.conf
/usr/sbin/orbi-dnsmasq -h -n -c 0 -N -i br* -r /tmp/dns/resolv.conf -u root

 

Message 36 of 43
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Aspirant

Re: RBR850 frequently issuing DNS REFUSED responses

Thank you for posting these instructions. I have been working with Netgear support but they jsut suggested I return the device to the store vs troubleshooting. 

 

I enabled telnet on the Orib and connected via the Windows built in telnet client. When I try to run the first line I get an error saying "copy: not found" 

 

root@RBR750:/tmp/dns#
root@RBR750:/tmp/dns# copy /usr/sbin/dnsmasq to /overlay/upper/usr/sbin/orbi-dns
masq
/bin/ash: copy: not found

 

Am I missing a step? 

Message 37 of 43
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Tutor

Re: RBR850 frequently issuing DNS REFUSED responses

You have to use Linux commands I believe. For example "CP" for Copy function.

Message 38 of 43
Highlighted
Tutor

Re: RBR850 frequently issuing DNS REFUSED responses

May be @arildj can write exact commands to execute.

Message 39 of 43
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Apprentice

Re: RBR850 frequently issuing DNS REFUSED responses

Yes I could do that, but I see there is a big risk for people to brick their Orbi-routers when not used to work on unix-systems.

And I would not be responsible for this, as my guide could may be missread or badly written by me Smiley Happy

 

I have reported the bug found in dnsmasq and I hope Netgear will work on this and make a patch for everyone to install.

 

Message 40 of 43
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Prodigy

Re: RBR850 frequently issuing DNS REFUSED responses

If you are using Windows, the easy and safe workaround is to set the DNS settings for your network connection to go directly to the DNS server IP address instead of through the Orbi.  This workaround worked for me on my Windows laptop and eliminated the intermittent DNS failures.  I used google DNS 8.8.8.8 but you can substitute your ISP's DNS address instead.

  1. Hit the Windows key and search for "control panel"
  2. Network and Internet
  3. Network and Sharing Center
  4. On the left, Change Adapter Settings
  5. For each wi-fi or other network adapter used, right-click and select Properties
  6. Select Internet Protocol Version 4 (TCP/IPv4) in the list and press Properties
  7. The second checknox is set to Obtain DNS Server Address Automatically.  Change it to Use The Following DNS Server Addresses
  8. Enter 8.8.8.8 and 8.8.4.4 (the Google DNS addresses)
  9. Press OK

Now it should bypass the Orbi for DNS and go straight to the DNS servers.

 

Message 41 of 43
Highlighted
Aspirant

Re: RBR850 frequently issuing DNS REFUSED responses

Same problem with RBR750. 


@arildj wrote:

Yes I could do that, but I see there is a big risk for people to brick their Orbi-routers when not used to work on unix-systems.

And I would not be responsible for this, as my guide could may be missread or badly written by me Smiley Happy

 

I have reported the bug found in dnsmasq and I hope Netgear will work on this and make a patch for everyone to install.

 



@arildj wrote:

Yes I could do that, but I see there is a big risk for people to brick their Orbi-routers when not used to work on unix-systems.

And I would not be responsible for this, as my guide could may be missread or badly written by me Smiley Happy

 

I have reported the bug found in dnsmasq and I hope Netgear will work on this and make a patch for everyone to install.

 


 

Message 42 of 43
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Aspirant

Re: RBR850 frequently issuing DNS REFUSED responses

I had the same problems w/ my 750 and tried all the troubleshooting steps as well as opening a support case with Netgear. I was unable to fix the issue with DNS. 

 

I ended up just flipping my cable modem (Xfinity) back to router mode and set the Orbi to AP mode. You really don't lose a lot of functionality (I can still see which devices are connected to each satellite in the Orbi application) in AP mode. This fixes the DNS issue as your cable modem takes over this functionality.  Strange you have to do this for such a high end system...but the signal strength/wired satellites makes it worth keeping. 

Message 43 of 43
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