Murus Lite is the entry level firewall front end. It features inbound filtering and logging and can be used to protect services running on the Mac. Despite being free Murus Lite is not a tryout or demo. It is a full featured app and is a good starting point for the novice user.
anchor apple generic and identifier "it.murus.Murus-Menulet" and (certificate leaf[field.1.2.840.113635.100.6.1.9] /* exists */ or certificate 1[field.1.2.840.113635.100.6.2.6] /* exists */ and certificate leaf[field.1.2.840.113635.100.6.1.13] /* exists */ and certificate leaf[subject.OU] = RNLG254GCK)