Date: Thu, 15 Mar 2012 13:30:07 -0700 From: Chuck Swiger <cswiger@mac.com> To: =?iso-8859-1?Q?Seyit_=D6zg=FCr?= <seyit.ozgur@istanbul.net> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: Malformed syn packet cause %100 cpu and interrupts FreeBSD 9.0 release Message-ID: <13511933-562D-4887-951B-5BB01F62AB00@mac.com> In-Reply-To: <3807CE6F3BF4B04EB897F4EBF2D258CE5C05F28C@yuhanna.magnetdigital.local> References: <3807CE6F3BF4B04EB897F4EBF2D258CE5C05F221@yuhanna.magnetdigital.local> <38FA7BAB-AC2B-4515-85CF-27F77C3F4313@mac.com> <3807CE6F3BF4B04EB897F4EBF2D258CE5C05F28C@yuhanna.magnetdigital.local>
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On Mar 15, 2012, at 1:17 PM, Seyit =D6zg=FCr wrote: > Thanks for quick reply.. but i don't use firewall. i tried to use PF..=20= > Packer filter stucks up to 100.000 syn packets flooding(on open = port).. Without packet filter it handle much more syn flooding. Like = 1Mpps can handle w/o interrupts that i see on my equiment > But in this case "malformed packets" i got interrupts also input = packet error.. cause %100 cpu.. > Is there any way to stop them without firewall ? Any rfc kernel = feature can check and stop those bogus packets ? > Or do i something wrong on PF ?=20 I prefer IPFW myself, but you probably ran out of stateful rule slots. = For a high-volume services which is expected to be Internet-reachable = (ie, port 80 to a busy webserver), you really just don't want to have = stateful rules-- it's too easy to DoS the firewall itself, as you = noticed. In any event, you don't need state if you are just = blacklisting attack sources. You haven't really identified what you mean by "malformed", but maybe = you are talking about a SYN flood, in which case make sure that SYN = cookies and SYN cache are enabled... Regards, --=20 -Chuck
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