23.01 Upgrade unbound Issue

johnpoz

@steveits said in 23.01 Upgrade unbound Issue:

linkedin.com

They are not even using dnssec.. But I see this error checking their dns

linkedin.com/TXT: No response was received until the UDP payload size was decreased, indicating that the server might be attempting to send a payload that exceeds the path maximum transmission unit (PMTU) size. (2600:2000:2210::43, 2600:2000:2220::43, 2600:2000:2230::43, 2600:2000:2240::43, UDP_-_EDNS0_4096_D_KN)

bingo600

I have experienced in my setup , that "Unbound" caches a "non resolved answer too".

If i have forgotten to add ie. a new host to my zone , and i try to resolve it on a client. I get a "not found" as i should
But when i then add the host to bind9 , and retry the "lookup" , then i still get a "not found" from unbound.
If i try to resolve the name on the bind9 linux machine, it resolves fine.
Cure is to restart unbound , then it begins to work.

I know the "zones" specifies the TTL , but does it have to "cache a bad answer too" ...

I might have to dig into my "Cricket book" .....
Prob. to find out that TTL also applies to "non resolvables too, for that zone".

Well just don't GOOF in the first place ...

/Bingo

johnpoz

@bingo600 said in 23.01 Upgrade unbound Issue:

cache a bad answer

hmmm - I just did a quick look, and it doesn't seem like the gui exposes the

cache-max-negative-ttl:

Setting... this could have something to do with it.. Especially if you have min ttl set. There was a bug a while back I believe where even if you had cache-max-negative-ttl: set to say 1, sometimes this could get cached as your min ttl time vs the negitive ttl..

I will have to do a bit of looking at what the actual unbound.conf has - and what is default if not set. But maybe I missed it, but doesn't seem like that option is exposed in the gui to mess with even.

edit: ok I don't see it in the .conf - so looks like it would default to 3600 from the unbound documentation

   cache-max-negative-ttl: <seconds>
          Time to live maximum for negative responses, these have a SOA in
          the authority section that is limited in time.  Default is 3600.
          This applies to nxdomain and nodata answers.

You should be able to set that in the custom options for unbound, if its something you feel you want to adjust - maybe put in a feature request to expose that in the gui.

SteveITS

@steveits Also, to clarify, I do not think LinkedIn was the only issue at the time. I was on my phone and flipping between things. I vaguely recall some issues on web pages, and the LinkedIn app wouldn't load most things, which got my attention, especially since I'd just upgraded to 23.01 that evening. Their web site wouldn't load, so I started investigating. No further issues in the last few days after turning off DNSSEC. My testing was querying pfSense, I flushed DNS cache on my PC, etc.

johnpoz

@bingo600 ok did a bit of looking at the neg cache time..

So you can tell that neg cache is being used, if you looking up something you know will nx.. So for example I did a query for random.cnn.com

If I look in the unbound cache, I can see that its counting down the ttl from 3600

[23.01-RELEASE][admin@sg4860.local.lan]/var/unbound: unbound-control -c /var/unbound/unbound.conf dump_cache | grep lsjfdsld.cnn.com
msg lsjfdsld.cnn.com. IN A 32899 1 3554 3 0 1 0
[23.01-RELEASE][admin@sg4860.local.lan]/var/unbound: unbound-control -c /var/unbound/unbound.conf dump_cache | grep lsjfdsld.cnn.com
msg lsjfdsld.cnn.com. IN A 32899 1 3546 3 0 1 0
[23.01-RELEASE][admin@sg4860.local.lan]/var/unbound:

See where it goes down from 3554, to 3546.. You could try setting the min-neg cache setting to something lower and see if using that via similar test that I did.

moelassus

@bingo600 Which list are you using for DoH blocking? I'm currently using a list from "oneoffdallas" that appears to be maintained. Wondering if there is a better one.

SteveITS

@moelassus There's a TheGreatWall_DoH_IP list in pfBlocker, though the list itself says it was last updated in 2020.

moelassus

@steveits Yeah, TheGreatWall list doesn't appear to be maintained. For example, it doesn't include any of Apple's DoH servers. OneOffDallas's list was last updated in Dec 2022.

Trying to block DoH is really a pointless exercise because bad actors aren't going to use a well-known DoH server anyway. DoH is a scourge. ️

johnpoz

@moelassus said in 23.01 Upgrade unbound Issue:

going to use a well-known DoH server anyway

While I agree with you - it would be quite possible for some bad software to use something on their own, and not a well known doh server. What it does do is stop stuff that is just trying to do you a "favor" and use doh without specifically asking you.. Those would normally point to a well known doh service..

I block it - because I don't want my stuff using it, but sure if it just using some not well known doh server, not much I could do about that other than trying all of its https traffic, which is pretty difficult.

bingo600

@johnpoz said in 23.01 Upgrade unbound Issue:

You could try setting the min-neg cache setting to something lower and see if using that via similar test that I did.

Thanx .. I will try that

And it works ....

server:
#log-queries: yes
#log-replies: yes
# Set max failed lookup cache time
cache-max-negative-ttl: 10
#

[23.01-RELEASE][admin@fwall]/var/unbound: unbound-control -c /var/unbound/unbound.conf dump_cache | grep .cnn.com
msg garbage.cnn.com. IN A 33155 1 6 3 0 1 0
msg cnn.com. IN DS 33152 1 6 0 0 3 0
[23.01-RELEASE][admin@fwall]/var/unbound: unbound-control -c /var/unbound/unbound.conf dump_cache | grep .cnn.com
msg garbage.cnn.com. IN A 33155 1 4 3 0 1 0
msg cnn.com. IN DS 33152 1 4 0 0 3 0
[23.01-RELEASE][admin@fwall]/var/unbound: unbound-control -c /var/unbound/unbound.conf dump_cache | grep .cnn.com
msg garbage.cnn.com. IN A 33155 1 3 3 0 1 0
msg cnn.com. IN DS 33152 1 3 0 0 3 0
[23.01-RELEASE][admin@fwall]/var/unbound: unbound-control -c /var/unbound/unbound.conf dump_cache | grep .cnn.com
msg garbage.cnn.com. IN A 33155 1 2 3 0 1 0
msg cnn.com. IN DS 33152 1 2 0 0 3 0
[23.01-RELEASE][admin@fwall]/var/unbound: unbound-control -c /var/unbound/unbound.conf dump_cache | grep .cnn.com
msg garbage.cnn.com. IN A 33155 1 1 3 0 1 0
msg cnn.com. IN DS 33152 1 1 0 0 3 0
[23.01-RELEASE][admin@fwall]/var/unbound: unbound-control -c /var/unbound/unbound.conf dump_cache | grep .cnn.com
msg garbage.cnn.com. IN A 33155 1 0 3 0 1 0
msg cnn.com. IN DS 33152 1 0 0 0 3 0
[23.01-RELEASE][admin@fwall]/var/unbound: unbound-control -c /var/unbound/unbound.conf dump_cache | grep .cnn.com
[23.01-RELEASE][admin@fwall]/var/unbound:

bingo600

@moelassus said in 23.01 Upgrade unbound Issue:

@bingo600 Which list are you using for DoH blocking? I'm currently using a list from "oneoffdallas" that appears to be maintained. Wondering if there is a better one.

I was basically following this guid
https://github.com/jpgpi250/piholemanual

URL List defined in pfS

And one of the lists got updates today

@moelassus - There's a pfSense specific guide in this doc
https://github.com/jpgpi250/piholemanual/tree/master/doc

I just skimmed the new guide ... He has made it very complicated.
I have attached the guide i followed, when i made it .... (a previous version)
Tip : USE FLOATING RULES ...
1-pfs-blockDOH-2021-simple.pdf.zip

/Bingo

inferno480

Definitely still seeing some Unbound issues since upgrading to 23.01... sometimes it takes a couple days to happen, and you can "fix it" by restarting unbound but it appears to randomly crash/restart on its own then log messages about DNSKEYs being insecure.

I also had the issue of IPv6 interfaces not being auto-added to the ACL; I had to manually override the ACL and put in all of my v6 subnets / internal IPs which I thought was the only issue (error would be Query Refused) but I just had an incident where unbound crashed and gave "Server Fails" in nslookup w/the ACL fix in place. I did nothing but wait a few moments and it was working again.

Every server restart you see in this log was not caused by me and this self-fixed after several moments of trying various DNS lookups (suddenly they all worked). Not really sure what to do about this except revert back to 22.05.

Under DNS Resolver > Advanced Settings I have "Prefetch DNS Key support" and "Harden DNSSEC Data" both UNchecked (been unchecked since I had the Query Failed/ACL issues two days after I upgraded)

Feb 22 17:32:33 unbound 73817 [73817:5] info: failed to prime trust anchor -- DNSKEY rrset is not secure . DNSKEY IN
Feb 22 17:32:33 unbound 73817 [73817:5] info: generate keytag query _ta-4f66. NULL IN
Feb 22 17:31:25 unbound 73817 [73817:2] info: failed to prime trust anchor -- DNSKEY rrset is not secure . DNSKEY IN
Feb 22 17:31:25 unbound 73817 [73817:2] info: generate keytag query _ta-4f66. NULL IN
Feb 22 17:30:24 unbound 73817 [73817:2] info: failed to prime trust anchor -- DNSKEY rrset is not secure . DNSKEY IN
Feb 22 17:30:24 unbound 73817 [73817:2] info: generate keytag query _ta-4f66. NULL IN
Feb 22 17:29:21 unbound 73817 [73817:1] info: failed to prime trust anchor -- DNSKEY rrset is not secure . DNSKEY IN
Feb 22 17:29:21 unbound 73817 [73817:8] info: failed to prime trust anchor -- DNSKEY rrset is not secure . DNSKEY IN
Feb 22 17:29:21 unbound 73817 [73817:1] info: failed to prime trust anchor -- DNSKEY rrset is not secure . DNSKEY IN
Feb 22 17:29:21 unbound 73817 [73817:8] info: generate keytag query _ta-4f66. NULL IN
Feb 22 17:29:21 unbound 73817 [73817:1] info: generate keytag query _ta-4f66. NULL IN
Feb 22 17:29:21 unbound 73817 [73817:0] info: start of service (unbound 1.17.1).
Feb 22 17:29:21 unbound 73817 [73817:0] notice: init module 1: iterator
Feb 22 17:29:21 unbound 73817 [73817:0] notice: init module 0: validator
Feb 22 17:29:21 unbound 73817 [73817:0] notice: Restart of unbound 1.17.1.
(...)

inferno480

@inferno480 I had to truncate the log to fit my post in, but can attach it... I just don't think there's much of value to review in it unless I increase debugging somewhere. i.e. it shows the symptom more than the cause.

johnpoz

@inferno480 do you have dnssec checked, and your forwarding? If so to where?

Have you checked the date time on your box?

inferno480

@johnpoz Time/Date seem accurate, they are NTP sync'd to 2.pfsense.pool.ntp.org - nothing noteworthy in the NTP logs

"DNSSEC" is checked under General Settings, I am using DNS Forwarding and my servers are Google DNS with the two V6 servers listed first, then the V4. DNS Resolution Behavior is "Use local DNS (127.0.0.1), fall back to remote DNS Servers (Default)". None of this was modified from 22.05 and I never had a problem until 23.01.

Any suggestions on additional logging I can enable (and how), for the next time it happens? I realize the randomness can make things difficult to troubleshoot.

SteveITS

@inferno480 uncheck DNSSEC and I suspect your issues will disappear. Unbound seems more sensitive in this version, when using it and forwarding. As discussed in this and other threads and the pfSense troubleshooting doc, DNSSEC is irrelevant if you’re already trusting the other DNS servers to do the lookup for you.

Gertjan

@steveits

If 'DNSSEC' is enabled, pfSense, during preparation of the unbound start, gets a copy of the good, known DNSSEC root key.

/usr/bin/su -m unbound -c '/usr/local/sbin/unbound-anchor -a /var/unbound/root.key'

If this fails, unbound will know it is using a not-good copy, and bail out.

So, you could check with :

/usr/bin/su -m unbound -4 -v -c '/usr/local/sbin/unbound-anchor -a /var/unbound/root.key'

to know if your IPv4 works.
The same for IPv6 :

/usr/bin/su -m unbound -6 -v -c '/usr/local/sbin/unbound-anchor -a /var/unbound/root.key'

Remember : no return message : all is well.
You could check content and time stamp of the /var/unbound/root.key file to see for yourself.

But : if you are forwarding, as said a million times time by now : disable DNSSEC.
Remember : forwarding means : you don't want certified DNS answers. You've decided to trust "some one else"
That's why forwarding is not the default mode.

SteveITS

It seems there's also an IPv6 ACL bug, if set to listen on "all" interfaces, that now has a patch:
https://forum.netgate.com/topic/176989/problems-with-pfsense-ipv6-dns-function-does-it-exist/36

SteveITS

@bingo600 said in 23.01 Upgrade unbound Issue:

following this guid[e]
https://github.com/jpgpi250/piholemanual

I see that includes OneOffDallas. (@moelassus)

It has an important typo though, the three local-zone lines have a leading space:

local-zone: " use-application-dns.net."

That doesn't work in my testing; needs to be:

local-zone: "use-application-dns.net."

bingo600

@steveits
Nice catch

Did you use the new giude , or the old one i posted as a"PDF/zip" here (bottom):
https://forum.netgate.com/post/1089443

I just briefly skimmed the new guide, and it seemed very "complicated" ..
I have just implemented the "Old guide".

/Bingo