Re: Snort3 generating multiple alert files

[João Soares <joaops () dei uc pt>]

You are absolutely right. The quotes made all the difference.

Adding log_pcap = { limit = 50, units = "M" } worked in conjunction with
alert_full, only after I removed the -L (or -A) option - makes sense!

This is all I needed for now. Thank you so much!

On 05/17/2016 02:46 AM, Russ wrote:
> On 5/16/16 9:14 PM, João Soares wrote:
> > Greetings,
> >
> > I had tried something similar to your suggestion before and it hadn't
> > worked, but now it does and I feel dumb.
> >
> > However, if I try, for example:
> >
> > alert_full = {file = true, limit = 50, units = MB}
> >
> > or
> >
> > alert_full = {file = true, limit = 50, units = M}
> >
> > The behavior stays the same (new file every 4Kb). Maybe there is also
> > some kind of bug with the units?
> The help is a little cryptic so let me expound on that.  The format is
> type name = default: help { range } so
>
>     enum alert_full.units = B: limit is in bytes | KB | MB | GB { B |
> K | M | G }
>
> the type, enum, is a string taking the values "B" or "K" or "M" or
> "G".  The help is possibly confusing here but it is saying that "B"
> means bytes, "K" means kilobytes, etc.  So, this should get what you want:
>
>     alert_full = { file = true, limit = 50, units = "M" }
>
> But, you could just default to bytes and do this instead:
>
>     alert_full = { file = true, limit = 50*1024*1024 }
>
> That you didn't get an error with units = M is a disappointing feature
> of Lua.  See the first item in the Gotchas.
> > As for your suggestion, I'm sorry but I'm not sure what you mean with
> > "add log_pcap to your conf".
> If you want to log the triggering packets to a pcap in addition to the
> full alerts, you can add this to your snort.lua:
>
>     log_pcap = { limit = 50, units = "M" }
>
> Note that the triggering packet may, depending upon your
> configuration, be a TCP acknowledgement in which case you won't get
> the reassembled data.  The unified2 log would have that data however.
> > Thank you so much for your replies, you've been of great help!
> Good - keep us posted on your progress.  :)
> > Best regards!
> >
> > On 05/16/2016 06:53 PM, Russ wrote:
> > > `snort --help-config alert_full` will show:
> > >
> > >     bool alert_full.file = false: output to alert_full.txt instead
> > > of stdout
> > >     int alert_full.limit = 0: set limit (0 is unlimited) { 0: }
> > >     enum alert_full.units = B: limit is in bytes | KB | MB | GB { B
> > > | K | M | G }
> > >
> > > So the default limit is zero, meaning unlimited, meaning you have
> > > hit upon a bug.  We will get that fixed.  In the meantime, you can
> > > set an explicit limit with:
> > >
> > >     alert_full = { file = true, limit = 12345678 }
> > >
> > > Note that since you already have alert_full in your conf, you can
> > > add this to your command line:
> > >
> > >     --lua "alert_full.limit = 12345678"
> > >
> > > Also, just to clarify earlier email, you can add log_pcap to your
> > > conf to get pcaps along with fast alerts, but you will have to line
> > > up time stamps to associate them.
> > >
> > > Thanks
> > >
> > > Russ
> > >
> > >
> > > On 5/16/16 10:09 AM, João Soares wrote:
> > > > Greetings,
> > > >
> > > > Thank you for your reply and suggestions! As for the -z option, I'm
> > > > currently doing load balancing externally as you said, I look
> > > > forward for that internal load balancing :)
> > > >
> > > > At the moment we're using a network tap to mirror lots of traffic,
> > > > including wireless frames, that is why I was using the -w option.
> > > > Thank you for your clarification.
> > > >
> > > > -A full goes to console by default you're right, but I have a
> > > > custom .lua file with
> > > >
> > > > alert_full = {file = true}
> > > >
> > > >
> > > > Which makes it go to a alert_full.txt file. My main issue is that,
> > > > it is constantly creating new files, when alert_full.txt reaches
> > > > ~4Kb. For example, it makes a new alert_full.txt.1483937582 and so
> > > > on. This one I would really like to fix.
> > > >
> > > > Best regards and thank you for your time
> > > >
> > > > On 05/16/2016 01:43 PM, Russ wrote:
> > > > > On 5/15/16 10:51 PM, João Soares wrote:
> > > > > > Greetings,
> > > > > >
> > > > > > I'm trying to learn and adapt to snort3 and it's not being easy.
> > > > > >
> > > > > > I'm running snort3 with this command:
> > > > > >
> > > > > > snort -l /root/snort-logs -A full -i eth0 -c etc/snort/snort.lua
> > > > > > -D -z 0 -d -e -w -X -y
> > > > > Some comments on your options:
> > > > >
> > > > > -z 0 will only help when you have multiple input sources or many
> > > > > pcaps since, at present, load balancing must be done externally. 
> > > > > Internal load balancing is coming up.
> > > > >
> > > > > -w applies to wireless and likely doesn't actually go with your
> > > > > eth0 interface (usually wired).  However, since you had that
> > > > > combination, I double checked and it appears that -w is no longer
> > > > > attached to any functionality and will likely be deleted.
> > > > > > I have a two questions and I would really appreciate it if you
> > > > > > guys could help me out:
> > > > > >
> > > > > > *1 *- Why is snort3 making a new alert file each time the
> > > > > > original file reaches approximately 4kb? How can I change that?
> > > > > Which options are giving you 4K logs?  -A full goes to console by
> > > > > default.
> > > > > > *2* - How can I make snort3 log both alerts and pcaps of
> > > > > > intrusions, I can't get it to work, I have tried combining both
> > > > > > -A and -L options but I can only get one of them to be logged.
> > > > > -A and -L are for two different run modes.  Use -A with -c to log
> > > > > intrusion events.  Use -L to just log all packets, that is, for
> > > > > sniffer mode.  When used together on the command line, the last
> > > > > one wins.
> > > > >
> > > > > Since you want to log intrusion events, you need a logger that
> > > > > captures packets along with the events.  I'm guessing that you
> > > > > want a separate pcap but there is no way to do that at present. 
> > > > > You can use -A u2 (short for -A unified2) and that will log the
> > > > > event followed by the triggering packet in the same file.  You can
> > > > > then use included u2boat utility to dump a pcap from the u2 log.
> > > > > > I'm sorry if these are really obvious questions, but I've read
> > > > > > the manual and I can't seem to find the answers.
> > > > > Did you look at the usage section?  There are several examples
> > > > > there.  If anything there is unclear, let us know.  We will be
> > > > > adding more than just reference material soon.
> > > > > > Best regards and thank you for your time!
> > > > > >
> > > > > > -- 
> > > > > > João Soares
> > > > > >
> > > > > > SIC - Serviço de Informática e Comunicações
> > > > > > https://helpdesk.dei.uc.pt
> > > > > > Department of Informatics Engineering
> > > > > > Faculty of Science and Technology
> > > > > > University of Coimbra
> > > > > >
> > > > > >
> > > > > > ------------------------------------------------------------------------------
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> > > > > > bring their own devices (BYOD) to work are irked by the imposition of MDM
> > > > > > restrictions. Mobile Device Manager Plus allows you to control only the
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> > > > > > https://ad.doubleclick.net/ddm/clk/304595813;131938128;j
> > > > > >
> > > > > >
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> > > > -- 
> > > > João Soares
> > > >
> > > > SIC - Serviço de Informática e Comunicações
> > > > https://helpdesk.dei.uc.pt
> > > > Department of Informatics Engineering
> > > > Faculty of Science and Technology
> > > > University of Coimbra
> >
> > -- 
> > João Soares
> >
> > SIC - Serviço de Informática e Comunicações
> > https://helpdesk.dei.uc.pt
> > Department of Informatics Engineering
> > Faculty of Science and Technology
> > University of Coimbra

-- 
João Soares

SIC - Serviço de Informática e Comunicações
https://helpdesk.dei.uc.pt
Department of Informatics Engineering
Faculty of Science and Technology
University of Coimbra

------------------------------------------------------------------------------
Mobile security can be enabling, not merely restricting. Employees who
bring their own devices (BYOD) to work are irked by the imposition of MDM
restrictions. Mobile Device Manager Plus allows you to control only the
apps on BYO-devices by containerizing them, leaving personal data untouched!
https://ad.doubleclick.net/ddm/clk/304595813;131938128;j

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