[ ctrace : bugs ]
 - TOS (-T) flag doesn't work.
 - when tcp ACK flag is set, ACK_SEQ should be valid.  at the moment,
   it's not!
 - when in -o (oldschool) mode, reported bytelength of packets should be 
   the real length (not fixed to an imaginary 40-byte value as it is now!)
 - validity checking for final-hop (target hop) packets on both
    . unimplemented ip protocols
    . tcp/udp
   ...needs to be implemented.
 - validity checking (sh/c)ould be binary, same for all protos?
   (unsure 'cause cksum calc may be done on send() by Net::RawIP... 
    and 'cause recent paper by ofir arkin and fyodor stated that 
    some icmps were returned by most linuxes with IP TOS changed to 0!)

