Re: CVS commit: src/sbin/ping

[itojun%iijlab.net@localhost]

>> >> permit -s 0.  from Maxim Konovalov
>> >What does it mean to use a 0 byte packet?
>> That just refers to the payload not the entire packet.
>Ah, and so it does.

        value after -s indicates the length of "Data" portion in the
        following diagram (echo request/reply format).  therefore with "-s 0"
        echo request packet will have no "Data" part.

itojun


from RFC792:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |     Code      |          Checksum             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Identifier          |        Sequence Number        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Data ...
   +-+-+-+-+-