this post was submitted on 18 Nov 2024
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16
Local domains constantly time out according to Uptime-Kuma (lemmy.dbzer0.com)
submitted 1 week ago* (last edited 6 days ago) by [email protected] to c/[email protected]
21 comments fedilink hide all child comments
 

I followed this tutorial to set up local domain names with SSL-certificates using DuckDNS: https://notthebe.ee/blog/easy-ssl-in-homelab-dns01/

I have three local domains for my Nginx Proxy Manager running on a VPS, for my self-hosted Nextcloud and my Proxmox-WebGUI both running on my local Homeserver. They follow the scheme service.dataprolet.duckdns.org.

Now I use Uptime-Kuma to monitor my services including the three domains and for some reason those three domains constantly time out after 48 seconds. I already set up the retries to 3, but to no avail.

I also use Pi-hole and Unbound and thought, that might be an issue, but testing my DNS using dig, mtr, traceroute, nslookup and host all returned normal values and no errors.

Does anybody have any idea what could cause this? I'm kind of clueless at this point. Thanks in advance!

EDIT: I don't get it.

  1. I can't ping duckdns.org on my home server. I only get 100 % packet loss. I can open the website in my browser though. I also can't ping www.duckdns.org, which redirects to appservers-duckdns-prod-1630339571.ca-central-1.elb.amazonaws.com. Also gets 100 % packet loss.
  2. I've added duckdns.org to my Uptime-Kuma and it got flagged as down because timeout of 48000ms exceeded but my other domains using DuckDNS were unaffected.
  3. I added another local domain to Uptime-Kuma to see the differences of having ignoring SSL errors tuned on or off and the number of retries:
  • Nextcloud
    • Ignore SSL error = false
    • Retries = 2
  • Proxmox
    • Ignore SSL error = true
    • Retries = 1
  • VPS
    • Ignore SSL error = false
    • Retries = 1
  • Homepage
    • Ignore SSL error = true
    • Retries = 2

Throughout the day only the newly added Homepage got flagged as down for 5 times. The 3 others were up the whole time.

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[–] [email protected] 4 points 6 days ago (1 children)

I've heard DuckDNS has become more unreliable. You could try another service like afraid.org and see if it makes a difference.

[–] [email protected] 1 points 6 days ago

Yeah, I suspect it's simply an issue on the side of DuckDNS. :/

[–] [email protected] 4 points 1 week ago* (last edited 1 week ago) (1 children)
  • Is your uptime kuma server on the same machine as your other services?
  • Are you using docker/podman? If so can you try to curl your services' domain from inside the container and see if they resolve?
[–] [email protected] 3 points 1 week ago (2 children)

Yes, Uptime-Kuma is running on the same domain as the other services, except the Nginx-Proxy-Manager, which runs on a VPS which I access via WireGuard. And yes, I'm using Docker. I tried curl'ing one of the domains from the Uptime-Kuma container and got the folllowing error: curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to service.datenprolet.duckdns.org:443. So thanks, now I have an idea about what I should investigate.

[–] [email protected] 1 points 1 week ago (1 children)

Are uptimekuma and whatever you're trying to monitor on the same physical hardware, or is it all different kit?

My first feeling is that you've got some DNS/routing configuration that's causing issues if you're leaving your local network and then going through two layers before coming back in, especially if you have split horizon DNS.

[–] [email protected] 1 points 6 days ago

Well, I'm monitoring the GUI of Proxmox on which I run a Debian VM which itself runs Uptime-Kuma and Nextcloud in Docker, so yes that's on the same hardware.

[–] [email protected] 1 points 1 week ago (1 children)

If you ping the domain from inside the container, does it succeed?

[–] [email protected] 1 points 6 days ago (2 children)

Yep

[–] [email protected] 1 points 6 days ago* (last edited 6 days ago) (1 children)

seems like your DNS works fine but your certs doesn't. Are you able to connect to your services on your browser normally, with SSL?

Edit: please also try curl -4 and curl -6 to your services from within the uptime kuma container to see if theres an ipv4/v6 issue

Another edit: seems like there is a dataprolet URL in your post and a datenprolet URL in your comments. It might just be a typo so also check that too.

[–] [email protected] 1 points 6 days ago (1 children)

Yeah, it works fine through my browser. Sometimes the websites load a little longer. I feel like it's an issue with DuckDNS as it's seemingly random when it works and when not.

IPv6 doesn't work:

docker exec -it Uptime-Kuma curl -6 proxmox.datenprolet.duckdns.org
curl: (6) Could not resolve host: proxmox.datenprolet.duckdns.org

Besides that the issue has disappeares since last night. I automatically restart all containers at night and moved from uptime-kuma:1 to uptime-kuma:latest. That shouldn't make a difference, but maybe it did?

And it's not a typo in my config, but in my post. But good catch. ;)

[–] [email protected] 1 points 6 days ago (2 children)

Could not resolve host

Then I guess you only define an A record in the DuckDNS panel. That's fine.

A while back I ran a somewhat similar Wireguard tunnel and can't connect. Turns out some MTU settings were lower than the docker's MTU and that breaks big packets like SSL handshakes. Restarting makes it work fine until things start congesting again.

Suffice to say this would be something I'll look at if the SSL errors reoccurs

[–] [email protected] 2 points 4 days ago (1 children)

So the MTU of Tailscale is actually 1280, but is the connection even going through the VPN or rather through my VPS, when Uptime-Kuma is trying to connect to my local domain?

[–] [email protected] 1 points 4 days ago (1 children)

It shouldn't go through the VPN although idk how to verify that. Do you still have the timeout errors in your monitors? What do those errors say?

[–] [email protected] 1 points 21 minutes ago

I just changed the Docker's MTU to 1200 and will observe the change.

[–] [email protected] 2 points 5 days ago

Thanks, since I access my home network and server through the public IPv4 of a VPS via Tailscale this could actually be the issue. I'll look into it, when I find the time.

[–] [email protected] 1 points 6 days ago (1 children)

Sorry I'm a bit confused. What kind of tracker are you using in uptime-kuma and what address is it pointing to?

[–] [email protected] 1 points 6 days ago (1 children)

What do you mean by tracker? I'm monitoring local domains, that point to local services and their respective web interfaces like Proxmox or Nextcloud. The local domains have a wildcard SSL certificate via DuckDNS.

[–] [email protected] 1 points 6 days ago* (last edited 6 days ago) (1 children)

Which one of those. You pick one when adding something new to monitor. Actually just send a screenshot of the uptime-kuma settings of one of the services that are giving you problems.

[–] [email protected] 0 points 6 days ago (1 children)

It's HTTPS, what else should it be, when I monitor a domain?

[–] [email protected] 2 points 6 days ago* (last edited 6 days ago) (1 children)

Well you keep saying monitor a domain, in that case a DNS monitor would make more sense than HTTP(s) since that's for monitoring a service. That's why I was a bit confused. But yeah try to enable the ignore SSL option and see if that changes anything. You didn't include a screenshot of the settings which makes a bit difficult to diagnose the problem so I will leave it here.

[–] [email protected] 1 points 6 days ago* (last edited 6 days ago)

Not sure how this helps, but here you go.