Re: Snort3 generating multiple alert files

["Al Lewis (allewi)" <allewi () cisco com>]

If you get snort3 from github the instructions are in the doc/start.txt file.

You can also see the instructions in the manual:

https://s3.amazonaws.com/snort-org-site/production/release_files/files/000/003/768/original/snort_manual.html?AWSAccessKeyId=AKIAIXACIED2SPMSC7GA&Expires=1463515261&Signature=JICgARmNdTsuNX4NC6sH27Z76Nw%3D#_building



Albert Lewis
QA SNORT/Sourcefire
SOURCEfire, Inc. now part of Cisco
9780 Patuxent Woods Drive
Columbia, MD 21046
Phone: (office) 443.430.7112
Email: allewi () cisco com

From: Ronald Hill [mailto:ronald.hill () dunbarsecured com]
Sent: Tuesday, May 17, 2016 2:14 PM
To: snort-users () lists sourceforge net
Subject: Re: [Snort-users] Snort3 generating multiple alert files

Does anyone have instructions on installing snort3?  All the documents that I find are incomplete and I have yet to 
successfully stand up a working instance.
Many Thanks.

Ronald Hill
SOC Analyst I
Dunbar Security Solutions
P: (443) 391 5480

From: João Soares [mailto:joaops () dei uc pt]
Sent: Monday, May 16, 2016 10:02 PM
To: Russ <rucombs () cisco com<mailto:rucombs () cisco com>>; snort-users () lists sourceforge net<mailto:snort-users 
() lists sourceforge net>
Subject: Re: [Snort-users] Snort3 generating multiple alert files


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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--

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

_______________________________________________
Snort-users mailing list
Snort-users () lists sourceforge net
Go to this URL to change user options or unsubscribe:
https://lists.sourceforge.net/lists/listinfo/snort-users
Snort-users list archive:
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Please visit http://blog.snort.org to stay current on all the latest Snort news!