The modules of David system which need to do an authorization of message senders (i.e. damsnmpdaud, dnmmsd, dgnsd), use the library, that checks whether an IP address of a sender matches with any record found in the file .known.host. The library expects to find the file in a directory pointed by a variable confdir in the file /etc/system-david.conf.

Records in the file .known.host are regular expressions specifying acceptable IP addresses.