Re: >2Gb capture files

[Chris Green <cmg () uab edu>]

Shriman Gurung <sg () dataconnection com> writes:

> It seems to me that even if your system supported 2Gb+ files,  
> you would not want to use them.  I find that managing big files 
> with the standard tools (tcpdump etc) takes ages and often crashes 
> things.

Agreed.  For a really bad tool to manage large amounts of data with:
ethereal.  Great for small bits of analysis and up to maybe 150mb
captures ( provided you have a 1gb memory machine )

It uses about 3x the size of the capture ( atleast in default settings
w/o DNS )

> People have suggested regular snort restarts, which by and large 
> I agree with, but you might have a really _really_ high traffic site
> in which case this might not be practical.  Back of envelope 
> calculation: say you have a (let's pick a number) 48Mbit/s worth of 
> evil traffic, ie 6Mb/s then you are filling up 2Gb every five minutes.  
> Who wants to restart Snort every five minutes?.
>
> In this scenario, if snort takes three seconds to restart you 
> potentially lose 18Mb of traffic, which sounds real bad to me.  If 
> you are concerned about losing info whilst snort is restarting, you 
> could set up two instances of snort on separate machines configured 
> to restart at different times.  For example A restarts snort at t, 
> t+5, t+10,.. and B at t+2, t+7, t+12,...

I think the real key is change snort so that the HUP mode to rotate
logs works better than reexecing itself ( essentially a restart ).

This is probably a todo for 2.0 but 1.8 is around the corner and this
should not be done for it.
> Alternatively, I guess you could set up a collection of machines 
> running snort (snorters?) and configure each to log a particular 
> type of traffic, the aim being to reduce the amount of traffic that 
> each one logged.  The downside of that is complexity.

Sounds like the netapp split / real secure solution although thats
definatly not for periods of time where you're going to have 48mbit of
net-cruft to log.
-- 
Chris Green <cmg () uab edu>
You now have 14 minutes to reach minimum safe distance.

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