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ROPE Language Reference - "$ip_tot_len"

The $ip_tot_len register contains an integer value that gives the total length of the packet being inspected.

RFC_791 explains this value like this..

Total Length:  16 bits

 Total Length is the length of the datagram, measured in octets,
 including internet header and data.  This field allows the length of
 a datagram to be up to 65,535 octets.  Such long datagrams are
 impractical for most hosts and networks.  All hosts must be prepared
 to accept datagrams of up to 576 octets (whether they arrive whole
 or in fragments).  It is recommended that hosts only send datagrams
 larger than 576 octets if they have assurance that the destination
 is prepared to accept the larger datagrams.

 The number 576 is selected to allow a reasonable sized data block to
 be transmitted in addition to the required header information.  For
 example, this size allows a data block of 512 octets plus 64 header
 octets to fit in a datagram.  The maximal internet header is 60
 octets, and a typical internet header is 20 octets, allowing a
 margin for headers of higher level protocols.

ROPE Language Reference - "$ip_tot_len"

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