Perle Systems P840 - Manual (Page 47)

Filtering
47
Pattern Filter Operators
The following operators are used in creating Pattern filters and will be discussed further in the following pages. For
additional information refer to the octet locations diagrams at the back of this manual. Each octet location may contain a
HEX value.
- offset Used in pattern filters to determine the starting position to start the pattern checking.
Example:
12-80 This filter pattern will match if the packet information starting at
the 12
th octet equals the 80 of the filter pattern.
| OR Used in combination filters when one or the other conditions must be met.
Example:
10-20|12-80 This filter pattern will match if the packet information starting at
the 10
th octet equals the 20 of the filter pattern or if the packet
information starting at the 12 th octet equals the 80 of the filter
pattern.
& AND Used in combination filters when one and the other conditions must be met.
Example:
10-20&12-80 This filter pattern will match if the packet information starting at
the 10
th octet equals the 20 of the filter pattern and the packet
information starting at the 12 th octet equals the 80 of the filter
pattern.
~ NOT Used in pattern filters to indicate that all packets not matching the defined pattern will be filtered.
Example:
~12-80 This filter pattern will match if the packet information starting at
the 12
th octet does not equal the 80 of the filter pattern.
( ) brackets Used in pattern filters to separate portions of filter patterns for specific operators.
Example: 12-80&(14-24|14-32)
This filter pattern will be checked in two operations. First the
section in brackets will be checked and then the results of the first
check will be used in the second check using the first portion of
the filter patter. If the packet information starting at the 14
th octet
equals 24 or 32, and the information at the 12 th octet equals 80, the
filter pattern will match.
@ Connect Used in pattern filters to indicate that the filter will only be active when the remote site connection is
down.
Example:
@12-80 This filter pattern will match if the remote site connection is down
and the packet information starting at the 12th octet equals the 80
of the filter pattern.
Bridge Pattern Filtering
Protocol Discrimination
Protocol discrimination may be required to prevent or limit the protocols that may traverse a bridged Local Area Network.