No DNS record found for when using a http proxy¶

You see a failing setup check telling you that "This server has no working internet connection" together with log messages starting with "No DNS record found for ..."

DNS pinning is a security measure against DNS rebinding attacks.

Our DnsPinMiddleware resolves the IP address for a given domain name and runs a couple of checks. For example, if the IP address belongs to a private network or is a loopback address.

To resolve a domain name to an IP address, your server must be able to resolve DNS queries. We are using dns_get_records, which uses the system resolver underneath.

Use the command below to check if your server can resolve DNS queries.

php -r "var_dump(dns_get_record('www.nextcloud.com', DNS_A));"

The expected outcome if DNS resolving works:

Command line code:1:
array(1) {
  [0] =>
  array(5) {
    'host' =>
    string(17) "www.nextcloud.com"
    'class' =>
    string(2) "IN"
    'ttl' =>
    int(300)
    'type' =>
    string(1) "A"
    'ip' =>
    string(15) "213.133.102.119"
  }
}

Solution¶

We recommend that you leave DNS pinning activated!

DNS pinning cannot work if your server cannot resolve DNS queries.

Disable it via occ:

php occ config:system:set --type boolean --value false dns_pinning

Or add the following line to your config.php:

'dns_pinning' => false,

More information¶

• https://en.wikipedia.org/wiki/DNS_rebinding
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-8f69-f9jg-4x3v