RFC (make up a number not in use) - Blueprint for setting up snort + pfblocker

A Former User · Jun 9, 2014, 3:52 PM

With regards to RAM usage, I've never seen snort go above 40% on a 2GB system.set up identical to this topic.

fearnothing · Jun 9, 2014, 5:35 PM

OK some more info here:
Using the Connectivity ruleset, 17% of 3051MB usage. And that's without most of the EmergingThreats rules.
Using the Security ruleset, 82%.

I was amused to see this in my log one of the times it failed…

Jun 9 19:27:50 	php: /snort/snort_interfaces.php: The command '/usr/local/bin/snort -R 60190 -D -q -l /var/log/snort/snort_em160190 --pid-path /var/run --nolock-pidfile -G 60190 -c /usr/pbi/snort-i386/etc/snort/snort_60190_em1/snort.conf -i em1' returned exit code '255', the output was 'Spawning daemon child... My daemon child 35849 lives... Daemon parent exiting (-1)'

Is there some way to export the config file so you can have a look to see what I might have done wrong?

A Former User · Jun 9, 2014, 5:36 PM

Let me take a wild guess that you are using AC. Use AC-BNFA.

EDIT: Actually AC-BNFA-NQ

fearnothing · Jun 9, 2014, 6:04 PM

Actually, AC-STD. However I seem to have solved it with the following process:

Set the search method to AC-BNFA - this brought memory usage down to 10%
Enable the desired rules - memory usage 13%
Change search method back to AC-STD - memory usage 14%.
Voila!

A Former User · Jun 9, 2014, 6:07 PM

And it will choke on the next rule update. Please use AC-BNFA-NQ. AC-BNFA-NQ replaced AC-BNFA, which in turn replaced AC*. Trust me, I was running AC-BNFA-NQ on multiple production networks, and I haven't created a black hole while doing so.

bmeeks · Jun 10, 2014, 1:38 AM

@jflsakfja:

And it will choke on the next rule update. Please use AC-BNFA-NQ. AC-BNFA-NQ replaced AC-BNFA, which in turn replaced AC*. Trust me, I was running AC-BNFA-NQ on multiple production networks, and I haven't created a black hole while doing so.

jflsakfja is correct. AC-BNFA-NQ is the best these days. Some of the other pattern matchers can gobble memory like crazy. And Suricata can be worse than Snort in this regard.

Bill

BBcan177 · Jun 10, 2014, 3:21 AM

@bmeeks:

@jflsakfja:

And it will choke on the next rule update. Please use AC-BNFA-NQ. AC-BNFA-NQ replaced AC-BNFA, which in turn replaced AC*. Trust me, I was running AC-BNFA-NQ on multiple production networks, and I haven't created a black hole while doing so.

jflsakfja is correct. AC-BNFA-NQ is the best these days. Some of the other pattern matchers can gobble memory like crazy. And Suricata can be worse than Snort in this regard.

Bill

Not if you have a lot of RAM lol…

EDIT:

I have been using "AC" on a 32GB box and "AC-SPLIT" on all others.

I will try to see if changing the "AC-SPLIT" to "AC-BNFA-NQ" fixes the crashing at rule updates sometimes.

A Former User · Jun 10, 2014, 8:38 PM

AC-BNFA-NQ.

AC-NQ is about 30% more ram efficient than AC-SPLIT, with an increased CPU usage.

AC (plain) is like killing a fly with a deathstar. AC-NQ replaced it, as in AC (plain) is now obsolete, you get no added benefits from AC over AC-NQ.

The best balance between RAM usage (more interfaces/more rules) and CPU is AC-BNFA-NQ. It's a single dropdown change, and an interface restart. Just try it, it will not bite.

On a side note, 32GB RAM is suricata's 10Gbps territory.

BBcan177 · Jun 10, 2014, 11:55 PM

Not that I don't believe you, but Its hard to find some good docs on this.. Do you have any links?

A Former User · Jun 11, 2014, 12:41 PM

If memory serves right, ac-bnfa-nq is the default if no method is specified. In order to be the default, it's probably the best, unless pushing snort to its limits, which unless you are in multiple-1Gbps territory, is nowhere near close to them.

A quick search gives this: http://sourceforge.net/p/snort/mailman/message/27113364/

A quick re-read of the entire thread will show that there are persons that think this topic is the absolute best way to set up snort on the entire internet. It might even give the hint to a certain group of people that want to build a statue of me, thinking I'm the messiah or something. A quick search around the forums will show others even going out of their way and lying that an i3 is faster than a p4 for a regular home connection while running snort.

If it meant completely tearing down your existing system and rebuilding it from scratch, then I understand the skepticism. As I said, it's a simple dropdown selection. Just try it, if you see that under your use case it chokes then try another method.

Ramosel · Jun 11, 2014, 2:33 PM

@jflsakfja:

A quick re-read of the entire thread will show that there are persons that think this topic is the absolute best way to set up snort on the entire internet. It might even give the hint to a certain group of people that want to build a statue of me, thinking I'm the messiah or something. A quick search around the forums will show others even going out of their way and lying that an i3 is faster than a p4 for a regular home connection while running snort.

I guess I am one of those people who sing your praise here… on my home system using your methodology and cookbook to get there, I cut my memory usage by more than half and CPU usage rarely comes off idle (AMD athlon 64 x2 with 4GB). I'm retired now but I spent enough years in the IT community (I was around before IT was IT) both as a worker bee and GOD that I can spot those who get it... vs. those who really understand it, live it, breathe it. I also learned not to argue with success until the next bright boy comes up with something better - and I've been on both sides of that coin. So yeah, I'd chip in a few coins towards your statue....BUT, considering you are still holding out on some of the rules that would be pretty helpful to us home users… we're talking "Winged Victory" here, not "David" (hint, one is missing their head) <wink>Rick</wink>

A Former User · Jun 11, 2014, 2:39 PM

The upcoming suricata topic will include a long section dedicated to creating suricata rules specific to a network gateway. There is no need to release my custom rules, since it will be explained how to create those rules on your own.

If most of the stuff I've written so far is considered short by me, then you'll realize what long means when you see the topic ;)

I'm actually putting the finishing touches (writing entire paragraphs here and there) on the first part, the firewalling part right now.

Mr. Jingles · Jun 11, 2014, 3:28 PM

@jflsakfja:

that want to build a statue of me, thinking I'm the messiah or something.

;D ;D ;D

Soloam · Nov 26, 2014, 10:47 AM

Hello all, I tried Suricata, but it's not yet compatible with my system, so back again to Snort. Just a quick question that I can't seem to find the answer in the topic. What should we do with the rules that are disabled by default? In the Suricata guide I see that it's recommended to activate all first and then disable the unwanted rules. Should we take the same approach in snort?

I tried once this and Snort would not boot on the interface, probably some rule that should not be set on. I looked on the system log and no error. I uninstalled all and started from scratch.

Thank you
Best Regards

A Former User · Nov 26, 2014, 1:54 PM

Yes, the recommended way to set snort/suricata is to enable all then disable the rules suggested in the topics/list.

Soloam · Nov 26, 2014, 10:58 PM

Thank you!

Any one had problems with rule "ET POLICY SSLv3 outbound connection from client vulnerable to POODLE attack
suppress" 1:2019416? I looked at both this tutorial and the suricata version, and both have this rule enabled! The problem is that if I leave this rule several google ip's are blocked, including play store and hangouts!

Best regards
soloam

A Former User · Nov 27, 2014, 12:57 PM

The rule is valid, you just need to completely disable SSLv3 (and v2 and v1). See your browser's documentation on how to do it.

Wepee · Jan 15, 2015, 5:18 PM

Sorry if I ask a silly question here, as I very new to SNORT.

I have been reading a lot, some I do understand but most I don't here.

Ok, here I begin the silly question ;D

Let take an example here, let's look the ET rules shown below:


emerging-botcc > all

emerging-chat > all except:
2010784 ET CHAT Facebook Chat (send message)
2010785 ET CHAT Facebook Chat (buddy list)
2010786 ET CHAT Facebook Chat (settings)
2010819 ET CHAT Facebook Chat using XMPP
2002327 ET CHAT Google Talk (Jabber) Client Login
2002334 ET CHAT Google IM traffic Jabber client sign-on
2001241 ET CHAT MSN file transfer request
2001242 ET CHAT MSN file transfer accept
2001243 ET CHAT MSN file transfer reject
2001682 ET CHAT MSN IM Poll via HTTP
2002192 ET CHAT MSN status change
2008289 ET CHAT Possible MSN Messenger File Transfer
2009375 ET CHAT General MSN Chat Activity
2009376 ET CHAT MSN User-Agent Activity

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Question here is the exception rules that I need to disable,
for example: 2010784 ET CHAT Facebook Chat (send message)

For the above rule if I need to do the exception, I need search the Signature ID
which shown above = 2010784, I need to a search on this rule and disable it

As you know this is a PAINSTAKING task of finding each and every Signature ID
2009376, 2009375…...etc and disable each and every one.

Question:

1) Is there a short-cut method of doing this mundane task faster? :(

2) This process of disabling each exception will start all over again since,
whenever there a new updated Snort package is released, and if updated,
then snort is completely unassigned to the WAN interface, and I have to
manually reassign snort to run on my WAN interface, and hence I need
to do the exception rules ALL over again, right? :(

Thank you.

A Former User · Jan 15, 2015, 7:20 PM

there is a new guide coming (work in progress) which should greatly simplify initial setup. For now I'm afraid that it's the clickety-click process :-)
That's not expected behavior. Did you contact bmeeks about it? I've never had to redo a setup, even after removing the package (keep settings on removal MUST be ticked) and reinstalling

bmeeks · Jan 15, 2015, 11:33 PM

@Wepee:

Sorry if I ask a silly question here, as I very new to SNORT.

I have been reading a lot, some I do understand but most I don't here.

Ok, here I begin the silly question ;D

Let take an example here, let's look the ET rules shown below:


emerging-botcc > all

emerging-chat > all except:
2010784 ET CHAT Facebook Chat (send message)
2010785 ET CHAT Facebook Chat (buddy list)
2010786 ET CHAT Facebook Chat (settings)
2010819 ET CHAT Facebook Chat using XMPP
2002327 ET CHAT Google Talk (Jabber) Client Login
2002334 ET CHAT Google IM traffic Jabber client sign-on
2001241 ET CHAT MSN file transfer request
2001242 ET CHAT MSN file transfer accept
2001243 ET CHAT MSN file transfer reject
2001682 ET CHAT MSN IM Poll via HTTP
2002192 ET CHAT MSN status change
2008289 ET CHAT Possible MSN Messenger File Transfer
2009375 ET CHAT General MSN Chat Activity
2009376 ET CHAT MSN User-Agent Activity

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Question here is the exception rules that I need to disable,
for example: 2010784 ET CHAT Facebook Chat (send message)

For the above rule if I need to do the exception, I need search the Signature ID
which shown above = 2010784, I need to a search on this rule and disable it

As you know this is a PAINSTAKING task of finding each and every Signature ID
2009376, 2009375…...etc and disable each and every one.

Question:

1) Is there a short-cut method of doing this mundane task faster? :(

2) This process of disabling each exception will start all over again since,
whenever there a new updated Snort package is released, and if updated,
then snort is completely unassigned to the WAN interface, and I have to
manually reassign snort to run on my WAN interface, and hence I need
to do the exception rules ALL over again, right? :(

Thank you.

Snort should never lose settings on an update if you have checked the "keep settings on uninstall" checkbox on the GLOBAL SETTINGS tab. If that is checked and you are still losing settings, then something extremely weird is happening, like maybe some older config.xml file getting auto-restored or something (just a wild guess).

If you want to "mass enable/disable" rule SIDS, the new SID MGMT tab is tailor-made for this. It uses the same syntax as PulledPork or Oinkmaster conf files. There are examples described within the included sample files installed with the Snort package now.

Bill