System Tunables Tab

The System Tunables tab under System > Advanced provides a means to set run-time FreeBSD system tunables, also known as sysctl OIDs.


In most cases, the best practice is to leave these tunables at their default values.

Firewall administrators familiar with FreeBSD, or users doing so under the direction of a developer or support representative, may want to adjust or add values on this page so that they will be set as the system starts.


The tunables on this page are different from Loader Tunables. Loader Tunables are read-only values once the system has booted, and those values must be set in /boot/loader.conf.local.

Creating and Editing Tunables

To edit an existing tunable, click fa-pencil.

To create a new tunable, click fa-plus New at the top of the list.

When editing or creating a tunable, the following fields are available:


The sysctl OID to set


The value to which the Tunable will be set.


Some values have formatting requirements. Due to the vast number of sysctl OIDs, the GUI does not validate that the given Value will work for the chosen Tunable.


An optional description for reference.

Click Save when the form is complete.

Tunable OIDs and Values

There are many OIDs available from sysctl, some of them can be set, some are read only outputs, and others must be set before the system boots as Loader Tunables. The full list of OIDs and their possible values is outside the scope of this documentation, but for those interested in digging a little deeper, The sysctl manual page from FreeBSD contains detailed instructions and information.