SMB and Netbios Headers

Roman Kubiak atom at
Wed Apr 24 07:12:02 GMT 2002

I'm currnetly working on a sniffer. A WinPOP sniffer program, it's a proof of concept only.
But I got into problems.
1) I already found 3 kinds of WinPOPup messages using 137 UDP 138 UDP and 139 TCP ports
2) I cant find any structure definitions for Netbios UDP or SMB TCP packets. Such as you find in
    netinet/udp.h tcp.h ip.h
3) Is there some document describing the WinPOP service. ow the packets are bulit and how does
that mechanism works.
I also found that almost every client that claims to be compatible with WinPOP service is not compatible
with samba. On my network we use RealPopup from wich is nice small and fast
but it send messages using UDP port 138 and samaba does not recieve those messages. However RealPop has no
problem in recieving messages from samba witch uses 139 TCP. 

I'm writing here hoping for some help on the subject. Definitions of headers would be nice. The rest i can
figure out using tcpdump (witch makes a lot of SMb and NBT packet decoding). Any help is nice.


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