What is someone looking for??

[Ryan Matteson <x96matteson wmich edu>]

I am currently blocking out netbios UDP port 137 on my firewall and was
wondering what the following means in terms of security:

Jul  9 16:19:05 oscar kernel: IP fw-in rej eth0 UDP SOMEONES_IP:137
MY_IP:137 L=78 S=0x00 I=46484 F=0x0000 T=111

I have gottena  few 100 of these and was wondering if there are some
vulnerabilties related to netbios out there?? What do the S/I/F/L fields
stand for?? I assume T= TOS? Thanks for any info I would appreciate any
info/URL's now. Is there a way to tell tcpdump to dump all netbios
packets originating from outside my present class C to a file for future
viewing?? Thanks again I apprecaite the help

Ryan