Administrator’s Handbook
•The host 199.211.211.17 is the source of the Telnet packets you want to block, while the destination address is any IP address. How these IP addresses are masked determines what the final match will be, although the mask is not displayed in the table that displays the filter sets (you set it when you create the filter). In fact, since the mask for the destination IP address is 0.0.0.0, the address for Destination IP address could have been anything. The mask for Source IP address must be 255.255.255.255 since an exact match is desired.
•Source IP Address = 199.211.211.17
•Source IP address mask = 255.255.255.255
•Destination IP Address = 0.0.0.0
•Destination IP address mask = 0.0.0.0
•Using the tables on page 166, find the destination port and protocol numbers (the local Telnet port):
•Protocol = TCP (or 6)
•Destination Port = 23
•The filter should be enabled and instructed to block the Telnet packets containing the source address shown in step 2:
•Forward = unchecked
This
