Frequent DNS timeouts

Gertjan

@thundergate said in Frequent DNS timeouts:

cleared unbound cache

This can only happens when the resolver -unbound is told to stop, or restart, which is a controlled stop, to be started right afterwards.
It can take several seconds to do so.
The cache will be lost, but subsequent DNS resolving won't take long, typical is a fraction of a second.

If unbound restarts happen very often, you can start to 'feel' the absence of the DNS sub system.

So, ask your pfSense how often it restarts :

grep "Restart" /var/log/resolver.log

If it's just couple of times a day (lesser == better) : this is not your issue.

oopohj5Oo8shieZe1ree

@steveits After switching from forwarding to normal resolving I let things sit for a bit to see what would happen. It looks like unbound is restarting a lot:

Mar 15 08:01:04 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:08:33 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:12:20 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:12:45 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:13:39 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:29:45 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:34:44 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:35:41 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:42:09 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:42:34 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:49:47 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.
Mar 15 08:52:13 netgate unbound[20724]: [20724:0] notice: Restart of unbound 1.17.1.

Is there a known workaround for this?

SteveITS

@oopohj5oo8shieze1ree The most common cause for restarts is having DHCP set to register DHCP leases in DNS, which triggers a restart after each and every DHCP lease. Options are to not do that, or to make the lease long enough that it renews in "days" not "hours." (renewal is 1/2 of the lease duration)

oopohj5Oo8shieZe1ree

@steveits I believe I have that turned off (in Services -> DHCP Server -> Dynamic DNS ->
Enable registration of DHCP client names in DNS). However, it does appear to be registering DHCP host names with the DNS server regardless of this setting.

I've increased the lease time and will report back.

Thank you.

johnpoz

@oopohj5oo8shieze1ree unbound starting that often is going to be problematic that is for sure..

thundergate

@oopohj5oo8shieze1ree

Same for me - a lot of unbound restarts and I actually don't know why?!

johnpoz

@thundergate well no restarts here

[23.01-RELEASE][admin@sg4860.local.lan]/root: unbound-control -c /var/unbound/unbound.conf status
version: 1.17.1
verbosity: 1
threads: 4
modules: 2 [ validator iterator ]
uptime: 196553 seconds
options: control(ssl)
unbound (pid 56217) is running...
[23.01-RELEASE][admin@sg4860.local.lan]/root:

196K seconds - 54 hours... Which was when I restarted pfsense to fix my swap not showing on widget..

If unbound is restarting - especially that often, your not going to have a good time.. You need to figure out why its restarting, registration of dhcp is typical reason you would see restarts like that..

thundergate

@johnpoz Hm. Ok.

Did you enable those settings within unbound?

johnpoz

@thundergate no - it has been a known issue for years that registering dhcp restarts unbound. I only register static mappings

SteveITS

@johnpoz said in Frequent DNS timeouts:

known issue for years that registering dhcp restarts unbound

ref: https://redmine.pfsense.org/issues/5413

thundergate

@johnpoz Oh no - That's stupid?!

But I do need those DHCP leases to be seen to know what device does make all those requests.... Cannot stand with IP addresses only.

Used OPNsense before - but didn't had those issues, if I remember correctly?

SteveITS

@thundergate Then until resolved, as I noted above make your lease time longer. It will restart on average every ( (lease duration/2) / # leases ).

thundergate

@steveits Will have to look into it.

I'm quite disappointed. Never thought that such an error does exist within pfSense (and it does exist since a few years now).

Are you all not interested in name resolution and do only handle IPs?

For me unbound restarts every 2-5 minutes (doesn't look like it is the DHCP lease issue at all?!).

johnpoz

@thundergate said in Frequent DNS timeouts:

re you all not interested in name resolution and do only handle IPs?

All of the devices I have that I need to resolve or want to resolve via name I have reserved IP for ;)

johnpoz

@thundergate said in Frequent DNS timeouts:

DHCP lease issue at all?!).

well look in your dhcp log - does it match up or not.. My leases are 4 days long.. But 2 hour lease, with lots of devices yeah you could have a few an hour for sure..

SteveITS

@thundergate said in Frequent DNS timeouts:

not interested in name resolution and do only handle IPs?

Depends on the setup. Clients with Windows domains use Windows DNS so it's handled. Windows in general/SMB will discover an address by NetBIOS name anyway. Printers get static or reservations. So in most cases it isn't really needed.

thundergate

@steveits Main point where I do need it is within my pfBlockerNG logs to see what device is doing which requests and so on...

Gertjan

@thundergate said in Frequent DNS timeouts:

But I do need those DHCP leases to be seen to know what device does make all those requests....

DHCP will still work.
The only thing that doesn't happen anymore is that their, mostly stupid host names, like AZERFDGHH, and you know what that is : the doorbell, and 6 devices that all are called 'Android' and four 'iPad' and whatever, will pollute your DHCP leases list
If you really want to control, and start even to pretend that you want to know what devices belongs to who : "who is what and when" on your network, then gives them logical names, names you chose, and not the build in device name.
And, oh, before I forget : a lot of devices don't even give a host name to enter into the DNS, but the resolver will get restarted anyway ....
That issue is also solved .... by the pfSense admin, you, of course.

So : take a first step : list all the MAC addresses, and give them all names that you understand.
At the end, pfSense will contain a list with all the devices that you , and names that you can easily remember.
On the device side, for every device : you have nothing to do, as most use DHCP out of the box.
The day you find a device that was using a IP out of the DHCP server pool, you know on the spot that you have a new device on your network.

Static DHCP lease are read into the resolver unbound upon start and will not change. Except the day you add a new device to your network, and create the "MAC IP host name" for it.

[23.01-RELEASE][admin@pfSense.what-a-mess.tld]/root: unbound-control -c /var/unbound/unbound.conf status
version: 1.17.1
verbosity: 1
threads: 2
modules: 3 [ python validator iterator ]
uptime: 111205 seconds
options: control(ssl)
unbound (pid 24788) is running...

That's a bit more as 3 days for me, when I was testing UPS shutdown procedure.

@thundergate said in Frequent DNS timeouts:

For me unbound restarts every 2-5 minutes (doesn't look like it is the DHCP lease issue at all?!).

Actually, I hope for you that this is your issue.
If it's not : entering into the light the other X reasons why unbound gets restarted :
You WAN, or LAN or any other interface is bad, goes up and down all the time.
This will restart unbound, and many other processes also.
Evey x minutes ..
Not a good thing.
Or unbound is plain 'bad' : less plausible, as me and you use the same code : days without restart is possible.
Another reason : it has been seen that people wanted to update their pfblockerng feeds every hours or so. If the any of these lists actually changed => unbound gets restarted.

And then this example : remember that stupid doorbell mentioned above : it was to cheap, it had a broken dhcp client, it was asking a new lease every minute .... The pfsense admin was posting here, as he had checked "DCP registration" and did not look into the logs to see that that doorbell was asking a new lease every xx seconds.

Also : people don't feel or notice radio waves. Device do, as they need it for the wifi connection. When the device is at the edge of reach ability, the link gets set going up and down every x seconds. On every linkup, a dhpc request is fired. Your phone has now become a pfsense unbound killer.

Now you know why the DHCP registration is, by default, not checked.
Now you now (parts) of what need to be checked once in a while, before you check it.

I was hoping for a more permanent solution, years ago.
I'm not waiting any more I solved the issue for me, on my side. And DNS rocks, for me.

johnpoz

@gertjan said in Frequent DNS timeouts:

did not look into the logs to see that that doorbell was asking a new lease every xx seconds.

I have seen this - client just asks and asks and asks.. Even when they just got a lease good for hours or even days.

thundergate

Thx for all the feedback.

I did turn of register DHCP leases and will now start to add them by myself. As far as I understand it's a 'one time job' and then the client does have a static lease/IP and that's it?!