Date: Tue, 04 May 2021 16:24:29 +0000 From: bugzilla-noreply@freebsd.org To: ipfw@FreeBSD.org Subject: [Bug 192888] ipfw NAT vulnerable to simple DOS attacks Message-ID: <bug-192888-8303-QaTPtDz8b8@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-192888-8303@https.bugs.freebsd.org/bugzilla/> References: <bug-192888-8303@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D192888 Lutz Donnerhacke <donner@FreeBSD.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|Open |In Progress --- Comment #4 from Lutz Donnerhacke <donner@FreeBSD.org> --- I went through the source code and can drill the problem down to an full sc= an of an unsorted linked list in a given hash bucket. This eats CPU cycles for breakfast. A workaround is to increase the hash table size in sys/netinet/libalias/alias_local.h: #define LINK_TABLE_OUT_SIZE 4001 A short term solution is to make the hard coded parameters tunable. But the real solution is to find a data structure which allows sub linear access methods to the flow data. Possibly using a non blocking algorithm for access and modification. --=20 You are receiving this mail because: You are on the CC list for the bug.=
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