check_http and Hetzner DNS

[Marc Haber]

On Mon, Sep 30, 2024 at 12:29:08PM +0200, Dominik Robert wrote:
> I want to try the check_http plugin and everything works fine with this command: /usr/lib/nagios/plugins/check_http -w 5 -c 10 -H podologie-feiner-fuss.de -f follow —sni
> 
> I have problems with URLs which DNS is located at hetzner. For Example: /usr/lib/nagios/plugins/check_http -w 5 -c 10 -H it-knowledgebase.net -f follow —sni this does not work. Is there anything I can do? The architecture is the same except the first one is located at 1&1 and the other one is from hetzner.

Two things:

- sni is a https only thing, but your checks use plain http. I didn't
  get it to work at all with the -sni option.
- the it-knowlegdebase.net domain has IPv6, so check_http uses IPv6.
  That didn't work for me. Forcing IPv4 using -4 made it work.

Is your web server configured to serve the it-knowledebase.net site via
IPv6?

I would recommend monitoring IPv4 and IPv6 seperately.

Greetings
Marc

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