This parameter enables dynamically updating the black/white list for
screening clients without restarting DeleGate.
SCREEN overrides other access control specified by RELIABLE or PERMIT.
In combination with "-Eri" option, the screening is done without starting
the interpritation of the application layer protocol.
"reject" indicates forbidding only client hosts listed in the list, while
"accept" indicates allowing only client hosts listed in the list.
The list is given as a text file including an IP-address or a MAC-address
With SCREEN="reject", the text file DGROOT/etc/hosts.d/reject.txt is seen.
With SCREEN="accept", the text file DGROOT/etc/hosts.d/accept.txt is seen.
Note: the arp command must be available by your DeleGate to use MAC-address