icode rule option is used to check that an ICMP code value is less than, greater than, equal to, not equal to, less than or equal to, or greater than or equal to a specified integer value. This rule option can also check that ICMP code value is between a range of numbers, using the
<> range operator for an exclusive range check or the
<=> for an inclusive one.
Single value comparison:
# Check for an ICMP code value greater than 30 icode:>30;
# Check for an ICMP code greater than or equal to zero and less than 30 icode:0<=>30;