Comodo Firewall slowing down 10GBit LAN

Hi guys,

thought about posting it as a bug report but is probably more a performance issue. It will happen with any OS and any 10GBit connection. You can’t do anything about it other then to remove the comodo Filter in the interface or uninstall comodo.

So it would be nice that in the future this will no more happening.

Keep it up!

If you uncheck that option, I think Comodo Firewall won’t filter the traffic

That is absolutely true and I don’t understand why this post was moved to Firewall Help - CIS.


Everything else in turned off and it is a Ryzen 8-Core overclocked on my side.

I don’t seek help. Comodo please fix your software in this regard. :-\

https://forums.comodo.com/format-verified-issue-reports-cis/cis-firewall-forces-mtu-to-1500-bytes-killing-jumbo-frames-m665-t99106.0.html

Not really a bug but more of a wish to support jumbo frames. You need to reset the mtu or jumbo frame to default size. The firewall does not support jumbo packets.

Ok, thanks for your reply.
Jumbo frames are not activated in the driver of the NIC. MTU I have to search to find out, if it was altered.

MTU is still standart.

I also talked with a guy who had the same problem with comodo and he has a fiber connection. I bet it was never tested for 10 Gb and I hope it will get better with that.

How are you determining the slowdown being caused by the firewall? Do you also have the AV installed and enabled? Do you have web-filtering and viruscope enabled and set to monitor all applications? What response do you get when you try ping -f -l 1500 ? You should provide a test procedure with results between having the firewall driver enabled and disabled.

I have only the Firewall installed and everything else, witch is not shown in the screen, disabled. I get 10 Gb without the comodo driver, with it, it caps out at around 6 Gb, but I only did rudimentary testing. Your right, I really should provide a test procedure, still searching for a good one.

Thank God, it took me ages and a significant amount of efforts, I finally pin pointed the one which caused my 10G NIC to suck.

The worst part with this issue is even you exit the Comodo firewall application, it still impacts. This was the exact reason which I never suspected Comodo firewall. I tried different network card (the same ASUS one as yours and Intel X540), NIC firmware, NIC driver, OS (Windows 10, Windows 7, Debian), AMD vs Intel, difference motherboards, etc, and still found nothing. But after this extensive troubleshooting, I was able to conclude (1) the network card is OK, it works at 10G full speed in Linux out of box; (2) it seems to be the issue with my Windows 10.

Originally I thought it might be some setting I did. As the last attempt, I did a fresh Windows 10 install and the 10G link works at full speed without any setting or driver change. Then I became certain it must be something on my Windows 10 which caused this issue. I checked the setting one by one and then install the applications one by one, and here we go, the Comodo firewall.

It’s nothing to do with jumbo frame. Standard 1500 MTU is still impacted. It seems the engine or filter driver can only process at approx max 5Gbps inbound and 2Gbps outbound data throughput. When copying files inbound, I can notice the copy progress window has intermittent freezing. Originally I couldn’t understand this on my AMD 3900X PC with 32G RAM and right now it all makes sense.

It seems it doesn’t allow me to uncheck the fitler driver in NIC. I will try it again and if it doesn’t work, I will change to a different firewall.

Yes, it is a performance issue with Comodo firewall. Probably unlikely to affect a lot of people because most Windows 10 users probably only have 1Gbps NIC and those 10Gbps NIC users use Linux or Windows Server more.