Netopia D3232 User Reference Manual page 75

Write a filter rule that blocks the class C subnet represented by 200.1.1.0/25 from accessing the net.
Filter Rule:
Incoming packet has the source address of 200.1.1.28
To determine if the packet will match on the filter, perform a Boolean AND on the source IP address and the
filter's source IP mask:
IP Address
200.1.1.28
AND
255.255.255.128
This incoming IP packet has a source IP address that matches the network address in the Source IP Address
field (whose last byte is binary 00000000) in the Netopia D-Series. This will not forward this packet.
Filter Rule:
Incoming packet has the source address of 200.1.1.184.
IP Address
200.1.1.184
AND
200.1.1.0
255.255.255.128
Forward = No
Binary Representation of
the last byte of the IP
address
00011100
10000000
00000000
200.1.1.0
255.255.255.128
Forward = No
Binary Representation
10111000
(Source IP Network Address)
(Source IP Mask)
(What happens on match)
(Source address in incoming IP packet)
(Perform the logical AND)
(Logical AND result)
(Source IP Network Address)
(Source IP Mask)
(What happens on match)
(Source address in incoming IP packet)
Security 8-75