Creating Packet Filters
12-15
4
Enter executable instruction #3:
eq
# if the two values on the top of the stack are equal,
# then return a non-zero value
Packet Filter Two.
This filter is designed to accept packets within the
socket range of 0x76c and 0x898. These steps show how to create this filter:
1
Name the filter:
“Socket range filter”
2
Enter executable instruction #1:
pushLiteral.w 0x76c
# put the lowest socket value on top
# of the stack
3
Enter executable instruction #2:
pushField.w 30 # put the value of the socket from the
# packet on top of the stack
4
Enter executable instruction #3:
ge
# compare if the value of the socket is greater than
# or equal to the lower bound
5
Enter executable instruction #4:
pushLiteral.w 0x0898 # put the highest socket value on
# top of the stack
6
Enter executable instruction #5:
pushField.w 30
# put the value of the socket from the
# packet on top of the stack
7
Enter executable instruction #6:
lt
# compare if the value of the socket is less than the
# upper bound
8
Enter executable instruction #7:
and # “and” together with “ge” and “lt” test to determine
# if the socket value is “within” the range. If it is,
# a “one” will be placed on the stack.
Summary of Contents for SUPERSTACK 2200
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Page 173: ...13 12 CHAPTER 13 CONFIGURING ADDRESS AND PORT GROUPS TO USE IN PACKET FILTERS ...
