Date: Sun, 29 Aug 2010 20:53:24 +0300 From: =?ISO-8859-1?Q?=D6zkan_KIRIK?= <ozkan.kirik@gmail.com> To: freebsd-net@freebsd.org Subject: Default router changes unexpectedly Message-ID: <AANLkTina3iO0QcFf8PSvEW-K5P5SM%2BH4jSeDBmU6yqmt@mail.gmail.com>
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Hi, I am using FreeBSD 7.3 STABLE-201004. IPFW + In kernel NAT and if_vlan used mostly. System has 3 em interfaces. Scenario is classical, LAN DMZ WAN. Sometimes default router changes unexpectedly. I inspected logs if someone logged in or changed route. I found nothing. This problem repeats at least 1 times per day. I wrote a shell script which monitors the default router. I saw that sometimes netstat -rn shows that default router is changed as 10.3.1.64 or 10.5.3.189 etc. which are client IP addresses but routing still routes to right router 212.X.Y.Z . After a while, routing really fails. I use em nics for all. At the weekends (when most clients are now working) i dont have any problems. I think some network packets affects the defaultrouter. I tried to block packets belongs to the IP addresses which shown as default router (10.3.1.64, 10.5.3.189 etc.. ). Then the problem is solved. I wonder how the default router can be changed with packets that came from network? How can i prevent this without writing firewall rules? Or which packets should I drop? Any ideas? Regards, Ozkan KIRIK Mersin University @ Turkey
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