Vulnerability Development: Possible probe of port 137 using udp 50?????

[Carder James O CNIN CONT <CarderJO () cninexchsrv08 crane navy mil>]

Hi Everybody,

        Just got a quick question.  I was reviewing logs on my shadow box
and noticed that for a period of a couple hours we had packet conversation
between two hosts ( one local and one remote ) through port 137 using udp
50.  My PIX acl's dont have any ruleset to allow this network in at all
except through say port 80 to our web servers.  Is this a known attack or
probe?  Thanks.

James Carder