3Com CoreBuilder 3500, Руководство по внедрению, Страница: 253 / 592

Long Custom Filter Example 253
4 Add an and statement to compare the results of step 2 with the results of
step 3:
and
# Compare if IP and in range.
This combination looks like this:
Name “Only IP pkts w/in socket range”
pushField.w 12 # Get the type field of the packet and
# place it on top of the stack.
pushLiteral.w 0x0800 # Put the type value for IP on top of
# the stack.
eq # If the two values on the top of the
# stack are equal, then return a non-zero
# value.
pushLiteral.w 0x76c # Put the lowest socket value on top of
# the stack (1900).
pushField.w 24 # Put the value of the socket from the
# packet on top of the stack.
ge # Compare if the value of the socket is
# greater than or equal to the lower bound
pushLiteral.w 0x0898 # Put the highest socket value on top of
# the stack (2200).
pushField.w 24 # Put the value of the socket from the
# packet on top of the stack.
lt # Compare if the value of the socket is
# less than the upper bound.
and # “and” together with “ge” and “lt” test
# to determine if the socket value is
# “within” the range. If it is in range,
# place a “one” will on the stack.
and # Compare if IP and in range.