Re: TCP Flags & MySQL

[Joel Esler <joel.esler () sourcefire com>]

TCP flags are in "decimal" value.  So.  2 would be SYN, and 18 would be 
a combination of two flags,  ACK = 16 and SYN = 2, so 18 = SYN, ACK.

The number in the tcp_win size is the "window size" of the packet. You 
can google all sorts of information concerning either of these topics.

You can write a BPF filter for Snort or tcpdump to look for these values 
(if you want to look at them in a dump format) with the bpf filter of 
'port 0 and tcp[13] = 2 or tcp[13] = 18'.

It might be easier to install a GUI for the db, like BASE.  That way you 
can "see" these alerts in your browser.

Joel

Paul Melson wrote:
> I have a Snort sensor logging to a MySQL database which is front-ended by a
> commercial application that allows for packet payload retrieval.
>
> This weekend, the system recorded a large number of "TCP port 0" alerts, and
> as expected it didn't record a payload.  However, it did record tcp_flags
> and tcp_win.  However, I am having difficulty interpreting the raw values in
> the tcphdr table into usable data.  Can someone point me to a doc that
> explains these values, or if I tell you that the tcp_flags values I see most
> often are 2 and 18, can you tell me which flags are set?
>
> Thanks,
> PaulM
>
>
>
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