syncookie CPU load

Dmitry Mikhailov dmitry at
Sat Aug 29 08:37:17 UTC 2015

Will PF synproxy allow to bypass the part of the code that causes high interrupt CPU usage? 


From: "Hien Phan" <phanquochien at> 
To: "Dmitry Mikhailov" <dmitry at> 
Cc: "freebsd-questions" <freebsd-questions at> 
Sent: Saturday, August 29, 2015 12:12:04 AM 
Subject: Re: syncookie CPU load 


pf has built-in synproxy support, you could try it. 

On Sat, Aug 29, 2015 at 1:09 PM, Dmitry Mikhailov < dmitry at > wrote: 

Doing a SYN flood test with FreeBSD on Xeon D (8 core) with syncookies enabled and the CPU load is around 20% (interrupts) at 150K pps. Is there any way reconfigure FreeBSD to bring this load down? Linux has a solution with netfilter synproxy which would not notice this low pps rate so I am wondering whether something similar is possible with FreeBSD? 

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