icmp_seq rule option is used to check that an ICMP sequence 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 Sequence value is between a range of numbers, using the
<> range operator for an exclusive range check or the
<=> for an inclusive one.
# Check for an ICMP sequence value of 0 icmp_seq:0;