Date: Thu, 19 Apr 2007 22:48:13 +0800 From: Zhang Weiwu <zhangweiwu@realss.com> To: freebsd-questions@freebsd.org Subject: Re: dhcpd assign duplicated IP address Message-ID: <4627812D.10708@realss.com> In-Reply-To: <20070419082211.4de04b69.wmoran@potentialtech.com> References: <1176949451.7739.15.camel@joe.realss.com> <20070419082211.4de04b69.wmoran@potentialtech.com>
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Bill Moran 写道: > In response to Zhang Weiwu <zhangweiwu@realss.com>: > > <snip> > >> 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!
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