What is the biggest attack in GBPS you stopped
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What I noticed was that pfSense would not let go of states for several minutes (5+). So when I was hit with 4.8M states, I'd still see 2.9M several minutes later. It wasn't until I rebooted the box several hours later that it returned to 3,500 states. IMHO boxes that are unresponsive after attacks still haven't released their states. Mine for whatever reason, recovered almost immediately after the attacks ceased.
Here is my hardware:
Intel Core i3-2100 Sandy Bridge dual core
Intel BOXDQ77MK LGA 1155 Intel Q77
4GB RAM
320 GB 7200RM HD
2 x Intel EXPI9301CTBLK 10/ 100/ 1000Mbps PCI-Express Network AdapterAlso note, that the initial SYN flood significantly burdened the UI but not the console, and when I increased states, the box was fine. The interface that was being attacked was disabled, but the box and the other three interfaces were working perfectly.
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My setup:
Cisco Comcast business CPE -> Cisco SG300 switch -> WAN side of two firewalls, one HW one VM
VM firewall is running on a Dell precision 7500 with dual Xeon 5650 processors and 48 GB RAM
ESXi 6.0
Official ESF pfSense 2.2.2 OVA (2GB ram and 2 cores)
WAN goes to a broadcom add in NIC
LAN is coming out the onboard NIC and plugs into a catalyst 2948 switchThe Hardware firewall is a VK40-TE. It runs the nanoBSD version of pfSense 2.2.2
Wan side plugs into the SG300
Lan into the 2948I have 5 IPs, so the two firewalls have different WAN interface IP addresses. Additionally, on the VM firewall, I 1:1 natted a windows box and opened RDP.
I set up two laptops on the LAN, one wireless, because I wanted to sit on my couch. The other was plugged into the 2948. The wired laptop was configured to use the VM as it's gateway. I fired of ping -t www.google.com, ping -t <other firewall="" ip="">, and ping -t <comcast public="" cpe="" ip="">.
The results were unexpected.
During the attack, I could ping the WAN interface of the "opposite" firewall and get a 2ms response, as if nothing was happening. After a few seconds, www.google.com failed to reply, or came back with 2100+ ms replies, through BOTH firewalls. Even the un attacked one. The Comcastic gateway device went from sub 10 ms pings to 300-400ms.
Even after the attack stopped, the Comcastic gateway failed to route traffic. I had to power cycle it to get back on the grid.</comcast></other>
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Did one more test, because I noticed a configuration error in my test setup.
After I reconfigured, I RDPd over to the test Win2k12 box's public IP, fired up wireshark and had supermule attack it.
I set up a ping to www.google.com through the un atacked firewall. It immediately started timing out.So again, my comcast gateway quickly crapped on itself, but pfSense didn't break a sweat. I was able to watch the packet capture over the RDP connection through the instance of pfSense under attack.
So, does the Cisco DPC3939B suck rocks, or was it "protecting" me by taking the brunt of the attack?
My states never got above 40k.
CPU hit about 30%, once.
RDP session never blinked.As soon as the attack stopped, www.google.com was pingable again.
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Its your GW Cisco box that crapped itself and took the heat of pfsense.
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Its your GW Cisco box that crapped itself and took the heat of pfsense.
I agree. My next step is to hit up a friend of mine that is the owner and chief packet plumber of an ISP. I'll haul the VM box over there and we'll test.
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After deleting the Vmware Tools then I disabled Apinger and NTPD.
The graphs on ESXi looked the same as "normal". No jitter from Apinger and NTPD afterwards.
Recovery was instant. Traffic graphs didnt respond well.
Might be relevant for tuning apinger.
https://forum.pfsense.org/index.php?topic=37740.msg194857#msg194857WRT the gui going unresponsive during an attack, you guys wont be logged into the gui in real life anyway, it will probably occur when you are at home cooking on the bbq, so the fact the gui goes unresponsive is perhaps best looked at as a side show distraction not really relevant in the scheme of things.
How are those affected handling the log data? Are you just writing to pfsense's own log or are you syslogging it out to another machine?
WRT to NTPD, I noticed back over Xmas some of the NTP pools were being dominated by certain countries. I didnt like this so I moved away from the default NTP pools used by pfsense and chose some of my own to put in pfsense, although building our own NTP server might be an option http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html but I should also point out, it might be possible to hijack/affect the GPS signals based on a hack I read about a while back (which has quite major significance when you think about it) but cant find the link to it atm.
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GUI is constantly monitored here by employees.
So yes it is.
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Ok, but I'd suggest that would be a minority but could be wrong as I know I'm not constantly logged in monitoring things.
Do you still log to syslog though so you have historical data in which to look back over data and spot any patterns?
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FYI PFSense defaults to an established TCP state to last 24 hours, even with zero traffic, as long as no FIN packet happens.
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GUI is constantly monitored here by employees.
So yes it is.
I have to agree here. One of the things i do for several clients is proactively monitor their firewalls.
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Ok, but I'd suggest that would be a minority but could be wrong as I know I'm not constantly logged in monitoring things.
Do you still log to syslog though so you have historical data in which to look back over data and spot any patterns?
I actually use the UI but also monitory with OpenNMS. I pulled my system logs after the attack and preserved some Wireshark pcaps. I have Security Onion running to do pcaps on the same mirrored interface, but haven't set up syslog yet. That shouldn't be too tough to do in the scheme of things.
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I have come a BIG step closer to locating the culprit.
Look at the graphs when NTPD is enabled.
It destroys the GUI completely and takes the interfaces offline in the GUI. No response from them. The graphs is a 3 minute attack and only maybe 10 seconds are showing.
Whats really interesting is the VmWare graph. When it spikes for the last time, the GUI comes back and the CPU graph in the GUI starts working again.
Wonder if NTPD and Apinger together could make something?
This makes sense because the kind of attack you hit me with is classified as an NTP attack.
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https://blog.cloudflare.com/understanding-and-mitigating-ntp-based-ddos-attacks/
https://blog.cloudflare.com/technical-details-behind-a-400gbps-ntp-amplification-ddos-attack/
https://www.acunetix.com/blog/articles/ntp-reflection-ddos-attacks/
https://forum.pfsense.org/index.php?topic=71396.0
"If you have appropriate WAN rules to stop the Internet from reaching your firewall's NTP server, then good news, you have nothing to do. However, if you have opened your NTP service up on purpose or if you have overly permissive rules (e.g. "allow all on WAN") and you don't want to change them, you can apply the following fix to change the behavior of the NTP daemon so it will no longer respond to the monlist command:"https://redmine.pfsense.org/issues/3496
https://redmine.pfsense.org/issues/3384 -
I dont have any NTP ports open on WAN. Only open port is 80.
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Totally clean install version 2.2.2 with no packages besides filemanager and no ports open.
No packetloss and responsiveness was 100%.
Load was not very high. No cpu hit 100% running 8 cores and 8GB RAM.
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Same install but now a port forward to port 80.
As soon as 1 cpu (nr.4) hots 100%, I get packetloss and GW goes offline.
There is NOTHING different done except a port forward. (HTTP). Total load is actually LOWER than with all ports blocked.
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CONCLUSION:
As soon as you have a working port forward (NOT DISABLED) to a server behind and pfSense needs to route it, youre dead.
Even at limited SYN Proxy state enabled and only 3mbit traffic passing through and states never reaches above 10%. Disabling every service on the firewall and still dead.
If you dont have a portforward, then its fine but that misses the main reason for having this setup….. IMHO.
Its definately FreeBSD/PF related and I dont believe its in the ESF code unless they alter the Packet Filter code.
I would be glad if anyone would run a base OpenBSD/FreeBSD with PF enabled as a frontend so we can continue testing.
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@Supermule, tell me, is the script posted in this thread the one causing the problem you see?
If so, does it also cause the problem you describe here? https://forum.pfsense.org/index.php?topic=87571.msg492268#msg492268
It seems like we are going around in circles at this stage this is why I ask.
Its also like CMB says here https://forum.pfsense.org/index.php?topic=87571.msg493401#msg493401
"DDoS is hell on stateful firewalls is the basic summary of this thread. It's not specific to anything in any particular firewall."The very nature of any stateful firewall will cause an increase in resource use like you are seeing.
With this is mind, what can you do to limit your exposure [edit]
ofto [/edit] the weakness of a stateful firewall?Lots of suggestions here
http://www.cisco.com/web/about/security/intelligence/guide_ddos_defense.htmlSome users who might be hosting a website that is providing services/products only to punters in their own country, can limit access to the ip addresses to those assigned. If its something being offered further afield like to a continent, then rinse and repeat the above but with all the continents ip address blocks.
If its something flogged globally, then consider a website sat behind the TLD specific to that country, ie if in the UK then a website assigned to a .co.uk could help, but then you'd need something to redirect the originating ip address to the correct country domain. This approach can lesson but not eradicate 100% a DDOS attack of sorts.
Perhaps having something that temporarily disables the port forward in realtime when the CPU activity reaches a threshold might be a way around the problem to avoid taking out the firewall if the other tuning options like increasing the default states et al doesnt work.
Either way, theres lots of ways to skin the cat!
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@Supermule, tell me, is the script posted in this thread the one causing the problem you see?
It can be altered to do so.
If so, does it also cause the problem you describe here? https://forum.pfsense.org/index.php?topic=87571.msg492268#msg492268
Yes. It takes more bandwith to do it. Limiting bandwith will make pfsense survive with no ports open.
It seems like we are going around in circles at this stage this is why I ask.
Its also like CMB says here https://forum.pfsense.org/index.php?topic=87571.msg493401#msg493401
"DDoS is hell on stateful firewalls is the basic summary of this thread. It's not specific to anything in any particular firewall."The very nature of any stateful firewall will cause an increase in resource use like you are seeing.
With this is mind, what can you do to limit your exposure [edit]
ofto [/edit] the weakness of a stateful firewall?This takes down a stateless setup as well with 15mbit of traffic. So its not related to the states.
Some users who might be hosting a website that is providing services/products only to punters in their own country, can limit access to the ip addresses to those assigned. If its something being offered further afield like to a continent, then rinse and repeat the above but with all the continents ip address blocks.
If its something flogged globally, then consider a website sat behind the TLD specific to that country, ie if in the UK then a website assigned to a .co.uk could help, but then you'd need something to redirect the originating ip address to the correct country domain. This approach can lesson but not eradicate 100% a DDOS attack of sorts.
Perhaps having something that temporarily disables the port forward in realtime when the CPU activity reaches a threshold might be a way around the problem to avoid taking out the firewall if the other tuning options like increasing the default states et al doesnt work.
It doesnt matter. The states itself is not the issue. Increase it and you wont hit the limit. As soon as you port forward, its dead. But then you cant host anything behind it.
Either way, theres lots of ways to skin the cat!
IMHO there is no cat to skin currently. As stated, if you port forward, youre dead.
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It doesnt matter. The states itself is not the issue. Increase it and you wont hit the limit. As soon as you port forward, its dead. But then you cant host anything behind it.
This behaviour which takes down stateless & stateful fw's is seen with that script posted in the msg link below?
https://forum.pfsense.org/index.php?topic=91856.msg523649#msg523649