CheckARPHeader

CheckARPHeader Element Documentation

CheckARPHeader — Click element; checks ARP header

CheckARPHeader([OFFSET, keywords OFFSET, VERBOSE, DETAILS])

Batching: Batching natively supported
Ports: 1 input, 1-2 outputs
Processing: agnostic, but output 1 is push

Input packets should have ARP headers starting OFFSET bytes in. Default OFFSET is zero. Checks that the packet's length is reasonable.

CheckARPHeader emits valid packets on output 0. Invalid packets are pushed out on output 1, unless output 1 was unused; if so, drops invalid packets.

CheckARPHeader prints a message to the console the first time it encounters an incorrect ARP packet (but see VERBOSE below).

Keyword arguments are:

OFFSET — Unsigned integer. Byte position at which the ARP header begins. Default is 0.
VERBOSE — Boolean. If it is true, then a message will be printed for every erroneous packet, rather than just the first. False by default.
DETAILS — Boolean. If it is true, then CheckARPHeader will maintain detailed counts of how many packets were dropped for each possible reason, accessible through the drop_details handler. False by default.

count (read-only) — Returns the number of correct packets CheckARPHeader has seen.
drops (read-only) — Returns the number of incorrect packets CheckARPHeader has seen.
drop_details (read-only) — Returns a text file showing how many erroneous packets CheckARPHeader has seen, subdivided by error. Only available if the DETAILS keyword argument is true.