Tag Archives: pdns

Fix PowerDNS “Old-style settings syntax not enabled”

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The PowerDNS Recursor started supporting YAML for configs in version 5.0.0. YAML is the default as of 5.2.0. You can still use the old config if --enable-old-settings is provided as a command line option when starting PowerDNS. If that option is not being used, and you are using the old config, you will experience the following errors.

msg="Old-style settings syntax not enabled by default anymore. Use YAML or enable with --enable-old-settings on the command line" subsystem="config" level="0" prio="Error" tid="0" ts="1732025541.126" configname="/etc/pdns-recursor/recursor.conf"


msg="YAML config found, but error occurred processing it" error="invalid type: string \"allow-from=127.0.0.0/8, 10.0.0.0/8, 192.168.0.0/16", expected struct Recursorsettings at line 17 column 1" subsystem="config" level="0" prio="Error" tid="0" ts="1732025541.817" configname="/etc/pdns-recursor/recursor.conf"

Fortunately, this is an easy fix.

  1. Convert old config to YAML with rec_control.
  2. Save as new YAML config.
  3. Remove old config.
  4. Start pdns-recursor.

Convert Config to YAML

The rec_control command can convert our old style config to a YAML config. This should automatically pull the default config in /etc/pdns-recursor/recursor.conf. 

rec_control show-yaml

Save output to /etc/pdns-recursor/recursor.yml

Remove the Old Style Config

We can remove the old config by renaming it, or deleting it.

mv /etc/pdns-recursor/recursor.conf /etc/pdns-recursor/recursor.conf.oldstyle

Or

rm /etc/pdns-recursor/recursor.conf

Start the PowerDNS Recursor

Start the pdns-recursor service using the systemctl command.

sudo systemctl start pdns-recursor

Verify there are no errors

sudo systemctl status pdns-recursor

Further Reading.

https://doc.powerdns.com/recursor/yamlsettings.html

How to Set up a PowerDNS Recursor

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The following are the steps needed to install a PowerDNS recursor on RHEL, Fedora, Rocky Linux, or AlmaLinux

Install from package manager with 

yum install pdns-recursor

Allow DNS through Firewall

sudo firewall-cmd --add-service=dns --permanent

Configure the `/etc/pdns-recursor/recursor.conf` file. The local-address is the DNS recursor, the allow-from, are the addresses you would like to allow access to 

local-address=192.0.1.2
allow-from=192.0.0.0/16, 10.0.0.0/8

Start and enable the `pdns-recursor` service

systemctl enable --now pdns-recursor

https://doc.powerdns.com/recursor/getting-started.html

Enable Syslog for PowerDNS Recursor

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  1. Enable Logging in PowerDNS Recursor Config
  2. Edit Systemd Unit File for PowerDNS to Allow Syslog
  3. Enable Logging in rsyslog Config File

The following links were helpful in setting things up.

https://doc.powerdns.com/recursor/running.html
https://www.reddit.com/r/linuxadmin/comments/9lc4jl/logging_queries_in_pdnsrecursor/

Enable logging in PowerDNS Recursor Config

First we need to find the line that says “disable-syslog” and uncomment/change it to 

disable-syslog=no

Next find the line that says “quiet” and uncomment/change it to 

quiet=no

Some other lines you may want to check and change

logging-facality=1
loglevel=6

Edit Systemd Unit File for PowerDNS to allow Syslog

Next we need to modify the Systemd unit file to allow PowerDNS Recursor to log to syslog.

systemctl edit --full pdns-recursor.service

On the ExecStart Line, remove the part that says

--disable-syslog

The resulting line should look something like

[Service]
ExecStart=/usr/sbin/pdns_recursor --socket-dir=%t/pdns-recursor --socket-dir=%t/pdns-recursor --daemon=no --write-pid=no --log-timestamp=no

Save the file.

Enable Logging in rsyslog Config File

Edit the rsyslog file 

sudo vim /etc/rsyslog.conf

Add the following line

local1.*        /var/log/pdns_recursor.log

This should now log all of the PowerDNS Recursor log info to “/var/log/pdns_recursor.log”

Restart the rsyslog and PowerDNS Recursor service

sudo systemctl restart rsyslog
sudo systemctl restart pdns-recursor

You should now see DNS request in the log file.

tail /var/log/pdns_recursor.log

They should also show up in the “/var/log/messages”