my %tcp_flags=(FIN => FIN,
               SYN => SYN,
               RST => RST,
               PSH => PSH,
               ACK => ACK,
               URG => URG,
               ECE => ECE,
               CWR => CWR);

my $cur_flags=$tcp_obj->{flags};
my @set_flags =
  grep { $cur_flags & $tcp_flags{$_} }
    keys %tcp_flags;

print join(",",@set_flags)."\n";