To ease maintenance of larger rulesets, OPNsense includes categories for the firewall. Each rule can contain one or more categories, which can be filtered on top of each firewall rule page.

New categories can be created from within the rule or you can use the category editor in Firewall -> Categories to manage them.

There aren’t a lot of properties available on a category, you can optionally set a color and when created from a firewall rule the item can have an “automatic” checkbox, in which case it will be removed automatically when unused.