Major DNS Bug 23.01 with Quad9 on SSL

jimp · Mar 15, 2023, 4:03 PM

@isotope1842 said in Major DNS Bug 23.01 with Quad9 on SSL:

@jimp Bullet number four of the previously included screenshot explicitly directs the user to check that setting. The pfSense documentation is actually more than advising. It is directing.

The page you quoted is a document about configuring DNS over TLS -- it's saying to check that if you want DNS over TLS. That's what that entire document is for.

It's not a part of the general setup or DNS resolver docs and so on. It's a recipe for users who are interested in that feature and want to know how to set it up.

There is nothing saying users should be following all of those recipes, they're there for reference for things users may want to do.

Isotope1842 · Mar 15, 2023, 4:16 PM

@jimp The context in which the instructions are provided is exactly for users who want to use an upstream DNS over TLS provider. The original poster here was reporting a bug in using Quad9 and I reported the same bug when using Cloudflare.

See the top of the same linked documentation:

"Pick a DNS over TLS upstream provider, such as a private upstream DNS server or a public service like Cloudflare, Quad9, or Google public DNS."

Following the instructions prior to 23.01 worked. Immediately after upgrading to 23.01, DNS fails until unchecking a single setting.

jimp · Mar 15, 2023, 4:16 PM

Yes, and? They still work for that and for many providers and users who want to enable that feature.

But you're trying to imply this is something the docs have told everyone they should be doing which isn't true. They don't advise everyone to do it, just people who are interested in that feature.

But none of this is helpful. We still need more information about how and why it's failing. We have yet to be able to reproduce this in a lab environment, and there are plenty of us running DNS over TLS without problems.

Isotope1842 · Mar 15, 2023, 4:19 PM

@jimp Steps to reproduce the problem:

Install pfSense 22.05 on a netgate device.
Configure DNS over TLS with Cloudflare.
Upgrade netgate device to pfSense 23.01.
Observe broken DNS for downstream clients.

jimp · Mar 15, 2023, 4:23 PM

@isotope1842 said in Major DNS Bug 23.01 with Quad9 on SSL:

@jimp Steps to reproduce the problem:

Install pfSense 22.05 on a netgate device.

Configure DNS over TLS with Cloudflare.

Upgrade netgate device to pfSense 23.01.

Observe broken DNS for downstream clients.

It is not that simple.

I have multiple lab VMs using DNS over TLS to Cloudflare and Quad9 that successfully resolve and have no problems.

stephenw10 · Mar 15, 2023, 4:28 PM

Mmm, I assume you are seeing the same intermittent behaviour as other users? It's not failing for every query with that configuration?

Isotope1842 · Mar 16, 2023, 2:43 PM

@jimp I just re-checked that single setting. DNS appears to continue to work. Curious to see whether it starts to fail again at some point.

jimp · Mar 16, 2023, 2:49 PM

@isotope1842 said in Major DNS Bug 23.01 with Quad9 on SSL:

@jimp I just re-checked that single setting. DNS appears to continue to work. Curious to see whether it starts to fail again at some point.

Since you hit it once it's likely to fail again at some point, but nobody has yet to be able to pinpoint exactly when/why it happens.

I've been periodically checking my lab systems and they all just keep resolving no matter what I do. But they are lab systems so the load is considerably lower than it would be in a live environment.

SteveITS · Mar 16, 2023, 3:05 PM

@isotope1842 There are a few threads on this topic, or variations thereof, and in another one someone posted their problem seemed likely to happen when opening a group/folder of bookmarks/favorites at once...implying a higher number of simultaneous requests might trigger it.

I was also unable to replicate my issue by simply (re)checking the DNSSEC option, but I left it off as recommended.

nononono · Mar 16, 2023, 4:17 PM

After playing alot more - it might be an issue with Quad9's TLS DNS limiting responses more than anything.

While there is nothing helpful in the pfsense logs, Quad9 just appears to stop replying and then start responding again - almost as if there is a limit being imposed by Quad9 on requests - but of course pfsense must have some role as it never occurred before 23.01

This network is a very high traffic network, so maybe others that see the same thing manage high traffic networks as well - either way the only long term solution has been doing TLS DNS through Cloudflare

As another point - DHCP lease registrations is definitely not fixed as claimed in 23.01, unbound still likes to reboot too much to consider enabling it - as such at the most I am still only registering the clients that need it via static mapping.

stephenw10 · Mar 16, 2023, 4:27 PM

Hmm, that would explain why we haven't been able to replicate it in test setups without the loading a production box has.

cmcdonald · Mar 16, 2023, 6:08 PM

@nononono

There were memory leaks and a segfault that were fixed. There is still ongoing work to eliminate the unbound reloads associated with lease registration events. I'm hopeful it will make it in 23.05.

nononono · Mar 16, 2023, 6:09 PM

@cmcdonald said in Major DNS Bug 23.01 with Quad9 on SSL:

@nononono

There were memory leaks and a segfault that were fixed. There is still ongoing work to eliminate the unbound reloads associated with lease registration events. I'm hopeful it will make it in 23.05.

That is great to hear! Hopefully that finally is solved

johnpoz · Mar 16, 2023, 6:13 PM

@nononono said in Major DNS Bug 23.01 with Quad9 on SSL:

DHCP lease registrations is definitely not fixed as claimed in 23.01

Where is that stated? What it says is a "crash" was fixed when unbound restarting

https://redmine.pfsense.org/issues/11316?#note-79

Where does it say that unbound is not going to restart on dhcp registrations.. The issue with unbound restarting every time there is something going on with dhcp is ok for some users.. but if you have clients renewing lever few minutes then your still going to have issues with unbound and dhcp - even if they fixed some crash that could happen.

SteveITS · Mar 16, 2023, 6:25 PM

@johnpoz said in Major DNS Bug 23.01 with Quad9 on SSL:

What it says is a "crash" was fixed when unbound restarting

It may be referring to https://docs.netgate.com/pfsense/en/latest/releases/23-01.html "A long-standing difficult-to-reproduce crash in Unbound...It is now safe again to enable DHCP registration alongside Unbound Python mode in pfBlockerNG." ...which is talking about pfBlocker vs DHCP, not that DHCP registration won't restart Unbound anymore. (I've seen others post about this sentence as well...)

JonH · Mar 21, 2023, 6:27 AM

@steveits said in Major DNS Bug 23.01 with Quad9 on SSL:

someone posted their problem seemed likely to happen when opening a group/folder of bookmarks/favorites at once...implying a higher number of simultaneous requests might trigger it.

Playing around with various settings, and I don't know if this has anything to do with the quoted comment, but I raised incoming and outgoing tcp buffers in resolver adv settings from default 10 to 20. I believe (or imagine) that it has reduced the frequency of unbound 'hangs' on my system.

joedan · Mar 26, 2023, 8:22 AM

@nononono

Just thought I would comment on this as I am seeing the same symptoms. It only just started happening recently and thought it was load related but not much has changed on my end except upgrading PFSense and associated packages.

I have turned parameter off this for now... Use SSL/TLS for outgoing DNS Queries to Forwarding Servers as I need the stability.

Summary:

Using Cloudflare SSL/TLS on 23.01 (ipv4 / ipv6 resolvers)
Build: 23.01-RELEASE (amd64) built on Fri Feb 10 20:06:33 UTC 2023
System Patches package with recommended fixes applied including a manual patch for redmine #13851
Machine Core(TM) i5-8365U, 16GB Ram, 128GB SSD
Internet Connection 100/20
Running a number of wireguard gateways (3 servers, both ipv4 and 6)
Running a number of packages including...

According to PFBlockerNG graph, my dns reply stats are around 10-20K per hour during the busiest times.

Over the last week or two, uptime Kuma randomly alerted me to dns issues which is the same time my family complained they couldn't access any websites or their game would fail stating their was no internet. This would happen randomly and would take a couple of minutes to clear up again.

Fortunately I had graylog setup and unbound in debug mode for the most recent errors above.

Looking at the logs I note the following messages around the time where DNS briefly cut out...

Looks like PfSense is not processing DNS requests quick enough for me. The sample above occurred whilst the internet link wasn't even loaded, neither was my machine.

I have turned this setting off and will monitor... Use SSL/TLS for outgoing DNS Queries to Forwarding Servers

I haven't done any further debugging and I hope this helps someone out, if not I apologise for this long post.

johnpoz · Apr 4, 2023, 5:40 AM

@joedan said in Major DNS Bug 23.01 with Quad9 on SSL:

10-20K per hour during the busiest times.

In your home? how many devices / users - you have a lot shit banging its head trying to resolve stuff your blocking.. That seems really high for a home..

That is what like 240K to 480K queries in 24 hours.. I see like 50k in 24 hours, and that is with 28 active devices doing dns.. Many of them banging their heads looking for shit that is blocked.

skogs · Apr 4, 2023, 1:41 PM

I also had occasional dns failures when using quad9 dns. I simply turned off forwarding mode and have had no issues with root servers doing the work.
I find this to be non-ideal, but at least functional.

n8rfe · Apr 4, 2023, 5:23 AM

Just reporting in here that I have the same issues with 23.01 and Quad 9 DNS when using unbound DNS

My settings were as follows on 22.05 since 22.05 was released with no issues with internet and DNS resolution.

pfsense ubound DNS resolver enabled
Using forwarding to Quad 9 DNS servers
DNSSEC unticked
Use SSL/TLS for outgoing DNS Queries to Forwarding Servers TICKED

Upgraded to 23.01 this weekend just gone 2nd April 2023. No other settings have changed on LAN network and no other firmware's have been upgraded on any devices on network so I am confident that the only change was the upgrade to pfsense from 22.05 TO 23.01.

Everything worked fine yesterday 3rd April until this morning when I now get multiple DNS resolution issues and cannot reach websites.

I have now changed the following single setting.

Use SSL/TLS for outgoing DNS Queries to Forwarding Servers UNTICKED

Websites are now resolving correctly.

I will continue to monitor DNS resolution over the coming days to see if the issue reappears and report back.