From owner-freebsd-questions@FreeBSD.ORG Thu Apr 19 14:49:06 2007 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 2E11616A403 for ; Thu, 19 Apr 2007 14:49:06 +0000 (UTC) (envelope-from zhangweiwu@realss.com) Received: from bossdog.realss.com (bossdog.realss.com [211.157.108.128]) by mx1.freebsd.org (Postfix) with ESMTP id E226D13C448 for ; Thu, 19 Apr 2007 14:49:04 +0000 (UTC) (envelope-from zhangweiwu@realss.com) Received: from localhost (unknown [127.0.0.1]) by bossdog.realss.com (Postfix) with ESMTP id B5D4F1C80C8 for ; Thu, 19 Apr 2007 22:49:30 +0800 (CST) Received: from bossdog.realss.com ([127.0.0.1]) by localhost (bossdog.realss.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 19929-11 for ; Thu, 19 Apr 2007 22:49:29 +0800 (CST) Received: from [192.168.1.200] (58.52.72.124.board.xm.fj.dynamic.163data.com.cn [124.72.52.58]) by bossdog.realss.com (Postfix) with ESMTP id 225C11C0003 for ; Thu, 19 Apr 2007 22:49:28 +0800 (CST) Message-ID: <4627812D.10708@realss.com> Date: Thu, 19 Apr 2007 22:48:13 +0800 From: Zhang Weiwu User-Agent: Thunderbird 1.5.0.7 (X11/20060918) MIME-Version: 1.0 To: freebsd-questions@freebsd.org References: <1176949451.7739.15.camel@joe.realss.com> <20070419082211.4de04b69.wmoran@potentialtech.com> In-Reply-To: <20070419082211.4de04b69.wmoran@potentialtech.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Virus-Scanned: amavisd-new at bossdog.realss.com Subject: Re: dhcpd assign duplicated IP address X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Apr 2007 14:49:06 -0000 Bill Moran 写道: > In response to Zhang Weiwu : > > > >> P.S. In recent days we some times got another network problem and I'm >> not sure if it's related to this DHCP server behavior. It happens on >> both Linux and Windows hosts that a host suddenly is no longer >> accessible (Ping no response). Check 'arp -a' on other hosts shows the >> host being accessed have wrong Mac Address. e.g. yesterday >> 218.193.55.195 suddenly become in-accessible, this host is Linux and we >> got this behavior on a nearby host: >> >> sappho # arping 218.193.55.195 >> Unicast reply from 218.193.55.195 [00:0F:EA:4B:82:58] 0.638ms >> Unicast reply from 218.193.55.195 [00:0F:EA:4B:82:58] 0.637ms >> Sent 113 probes (1 broadcast(s)) >> Received 113 response(s) >> sappho # arp -a 218.193.55.195 >> ? (218.193.55.195) at 00:02:2A:C1:53:87 [ether] on eth0 >> >> arping reply is different from arp cache. This host become accessible >> the next day. Strange. Are these two problems related? >> > > You have something seriously wrong somewhere. They may be related but > there's not enough information here to be sure. Consider installing > arpwatch on one or more systems and see if the reports it sends narrow > down the problem. I have followed Jeffrey's suggestion and reconfigured dhcpd.conf to make sure no host with specified IP address is within dynamic assigned IP range. I was mislead by my previous experience with Microsoft DHCP server configuration where a host with fixed IP address should be within the range. After updated dhcpd.conf I haven't see an IP conflict yet, I'll watch a few days. For the ARP issue, thanks for suggesting arpwatch. I'd like to take a deeper look into how ARP works later. Thanks!