sub parse_tcp_flags {
   my $flagword = shift(@_);
   my %flags = ("FIN"=>0,"SYN"=>0,"RST"=>0,"PSH"=>0,"ACK"=>0,"URG"=>0);
   $flags{FIN} = ($flagword & 0x01)? 1: 0;
   $flags{SYN} = ($flagword & 0x02)? 1: 0;
   $flags{RST} = ($flagword & 0x04)? 1: 0;
   $flags{PSH} = ($flagword & 0x08)? 1: 0;
   $flags{ACK} = ($flagword & 0x10)? 1: 0;
   $flags{URG} = ($flagword & 0x20)? 1: 0;
   return \%flags;
}