Taming the beasts… aka suricata blueprint

[A Former User]

Apologies for the late reply, but I was involved in a double car accident. Almost snapped my neck, spent two weeks immobilized in a hospital bed.

@all: don't expect me to be active these days. I'm mostly in and out of bed recovering from a series of injuries throughout my body.

@pfcode:

1. Yes, enable all, even originally disabled rules. Then go through the list and disable those mentioned.

2. Rules that cannot be found are rules that were deleted upstream (ET). In that case, please ignore them.

[pfcode]

@jflsakfja:

Thanks much,  Sorry about your car accident,  Feel better!

[stephenw10]

Wow, just read this.  :o

I wish you a speedy recovery.

Steve

[Cino]

speed recovery jflsakfja!!

[Soloam]

fast recovery jflsakfja!!!

[nug]

Firstly to jflsakfja, sorry to hear about your accident.  I hope you're OK!

So I've finally made it through the 29 pages (the first few I had to read quite a few times) and I still have a couple of noob questions.

1. I'm getting quite a few "ET SCAN NMAP -sS window 1024" alerts (among others) in my logs.  It adds the IP to the block list of Suricata, which is great.  But I continue to get these scans from the same IP.  Does this mean the blocking isn't quite happening or am I just being alerted that the scan is being attempted?  I would have thought if the block was there it wouldn't be getting any packets through at all?

2. Just in case, I manually added some of these IPs into an IP Alias to block on the floating tab in through WAN and out of LAN.  Is there a way of having Suricata automatically add IPs into a permanent block list Alias or something?  Even adding these rules manually I still get the alert in Suricata, which again I would have thought the firewall would block the packets way before Suricata would be seeing anything.

3. The default settings are to block hosts for 1 hour within Suricata.  Is there a particular reason why you wouldn't block them permanently?

Apologies if these are stupid questions!

[A Former User]

You are still seeing alerts because of the way snort/suricata work on pfsense. Follow the next steps through, and you will understand why.

1. A packet comes in on your WAN interface
2. A copy of that packet is immediately made, and passed on to snort/suricata
3. pf decides what to do with the packet
4. snort/suricata decides what to do with the copy of the packet
5. If rules allow it, pf passes on the packet to your LAN interface
6. If snort/suricata rules call for an alert, an alert is generated
7. The original packet has likely reached its destination
   8 ) The offending IP is added by snort/suricata (actually no, but good enough) to the blocked table.

The most important part is 2: that shows exactly how snort/suricata work, and why alerts are generated. Fast forwarding another round of that list, shows that by the time pf decides that a second packet from the offender should be blocked, snort/suricata already sees the copy of that packet, re-generating an alert. As you can see, no matter what you do, the alerts will always be generated.

The only 2 ways to stop those alerts is by using an upstream router to block packets from that IP, or using BPF to tell suricata to not inspect packets from those IPs, which is not currently supported nor encouraged (last time I tried it on my 4 million permanently banned IPs, the box crashed, on smaller lists suricata start up took a day or so).

You don't have to worry about the alerts being generated. That does not mean that packets are passing, they could be blocked and the alert will still be generated on the copy of the packet.

I like to set up the ban time as 28 days. Offenders (including so-called "state sponsored hax0rz") being mostly script kiddies they will come again with a packet that will generate an alert within that timeframe. The bonus of having snort/suricata work the way they do now, is that once an attacker generates an alert, and he keeps on coming, he will be perpetually banned. Each time an alert is generated, the timestamp for that IP is updated, which means resetting the timer back to 28 days.

Every now and then, manually inspect the snort/suricata blocked list, and decide on what to do. For example if a number of IPs from a certain /24 subnet are always there, they get added to a permanently banned list, that is used in a rule on all interfaces (block WAN side, reject LAN side). Not that it stops the alerts, but in case the blocked list is flushed (eg reboot?) the IPs are still banned.

@all: thanks for the wishes. Slowly recovering :-)

[neonmatt]

Got my 'new' home network almost up and going, so I popped in to see how the thread was doing. I had to comment and say jflsakfja I hope your recovery is going well!!

[abujammy]

jflsakfja thanks so much for all the time you've spent on getting this up and running.  I read through the ridiculously long thread on getting the half dozen sentences you wanted in order to begin working on the guide.  Now that that's done, what's the timeframe looking like on that and what kind of help do you need to get started?

[Mr. Jingles]

@abujammy:

on getting the half dozen sentences you wanted in order to begin working on the guide.

and what kind of help do you need to get started?

I've read this more than once, but I think I'm not quite sure what the question is. Now I'm not JFL, so your question isn't directed at me, but I'm still being curious as to what the question is ( ;D ).

[abujammy]

hahahaha well I thought it was pretty clear. ;)

Let me try to be more clear.  Do you need:

• Someone to help edit for English grammar?
• Someone to convert some of the forum topics over to github so that you can edit from there?
• Someone to grab pfSense screenshots, crop them and put them in a repo somewhere?
• Someone to write a section from scratch?
• etc
• etc
• etc

[A Former User]

Still recovering and becoming a regular at the doctors'. Went through everything so far, x-rays, CTs, EMGs, MRIs…(notice the "s" at the end of each one). Still have 2 MRIs to go through, but that's going to take a while, not scheduled for another 4 months or so. Not saying that the guide is going to be delayed until then, but for now, I'm more focused on easing back to my regular life and workflow.

I only ask for your patience for now  :). Bone marrow and nerves are slow in recovery...

The upside is that my head is still attached to my neck, that's good!

[TDJ211]

@jim82:

@jflsakfja:

Can I see a screenshot of the floating rule in question?

If you are talking about the "block all" floating rule, it should only apply to traffic destined for pfsense's ports (that's why there is a giant red warning under it).

Thanks for your reply. I guess the post above concerns the same confusion. Don't get me wrong, but you write the following:

Next up Floating tab:
Set up a rule but make these changes:
Action  Block
Quick  TICKED!!!
Interface  Hold CTRL and click on all interfaces EXCEPT LAN(admin) and SYNC
Direction  any
Source  any
Destination  any

If you read this directly(as I did, since I'm absolute beginner), your rule will block everything in/out on all interfaces, except "LAN".

I did this, and got confused. I could not wrap my head around, how on earth a Floating block ANY ANY ANY to all interfaces would possibly allow any traffic to pass through.

My suggestion is to clarify(maybe more red big letters) that this floating block rule is ONLY for the ports you specify as being web interface and SSH(which makes good sense).

Thanks for your guide, I'm looking forward to following the next steps.

BR Jim

Ahhhhh….thanks for the clarification! I read it that way too.

[dmitri_oga]

@jflsakfja:

Next up Floating tab:
Set up a rule but make these changes:

| Action | Block |
| Quick | TICKED!!! |
| Interface | Hold CTRL and click on all interfaces EXCEPT LAN(admin) and SYNC |
| Direction | any |
| Source | any |
| Destination | any |

DON'T CHANGE DESTINATION PORT RANGE!!! Had to add this since I confused a few people already :p

Those are pretty much the only changes you need to make. Save and apply the rule. When adding other floating rules, make sure this rule stays at the absolute top of the list.

I am either missing something or this is truly going over my head and I apologize for resurrecting an old(er) thread.

When I add the Floating rule, all traffic on my network grinds to a halt.
Can someone explain to me how to set it up correctly? I apologize for this, I've looked over the thread several times and can't come to an answer. I tried varying setups and, still, nothing.

Here's a link to my current rules:
Floating: http://i.imgur.com/oqVGRyD.png
WAN: http://i.imgur.com/kezi74q.png
LAN: http://i.imgur.com/n7g15kf.png

Thanks.

P.S., hope you're alright, jflsakfja. :D

[n3by]

you missed the destination admin ports for your pfsense box.

[dmitri_oga]

@n3by:

you missed the destination admin ports for your pfsense box.

So, they need to be in the LAN and Floating section? Also, I noticed I might've mislabeled the LAN and WAN Imgur links. Sorry.

[n3by]

Be careful with chosen ports, not to be used by normal applications because you will cut access to this ports.

You will put restriction rule from LAN only if you want to have specifics designated computers that can access the admin ports.

Attached floating rule for WAN and rule for LAN.

p.s.
you can use as destination: "This firewall (self)" instead of any


[dmitri_oga]

@n3by:

Be careful with chosen ports, not to be used by normal applications because you will cut access to this ports.

You will put restriction rule from LAN only if you want to have specifics designated computers that can access the admin ports.

Attached floating rule for WAN and rule for LAN.

p.s.
you can use as destination: "This firewall (self)" instead of any

Appreciate it! Thanks a lot. Kudos.

[A Former User]

So long and thanks for all the fish.

[pfcode]

@jflsakfja:

So long and thanks for all the fish.

Oh, NO.  r you leaving us? whats happening?