Date: Fri, 18 May 2001 00:29:56 -0700 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Will Andrews" <will@physics.purdue.edu>, <questions@FreeBSD.ORG> Subject: RE: Promiscuous mode? Message-ID: <005001c0df6c$56820f00$1401a8c0@tedm.placo.com> In-Reply-To: <20010518012637.Q26877@casimir.physics.purdue.edu>
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Under FreeBSD, programs like trafshow are "bpf clients" they use the bpf interface which puts the card in promiscious mode. In your scheme, however, that hub that the DSL line is connected to and that the BSD box and the other computers are connected to, it MUST be a flat hub, NOT a switch. Switches will normally prevent all the traffic from being seen. As long as it's a hub you will be fine. the snmp daemon only looks at traffic that is directed to the computer, not at all traffic on the Ethernet. BTW, what is the DSL CPE that your using to connect to the DSL line? Some of the CPE's have SNMP in them and can give you traffic stats that you can track with a program like MRTG. Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com >-----Original Message----- >From: owner-freebsd-questions@FreeBSD.ORG >[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of Will Andrews >Sent: Thursday, May 17, 2001 11:27 PM >To: questions@FreeBSD.ORG >Subject: Promiscuous mode? > > >Hello, > >I'm trying to graph the usage of a DSL line which is connected to a hub, >to which several computers are connected to. However, since the traffic >is not going through my computer, I need to figure out a way to have it >watch all the traffic on the hub, and from what I understand, I need to >put the NIC in promiscuous mode. So the first question would be: how do >I put it in promiscuous mode 100% of the time, besides starting a >sniffer like tcpdump et al? I couldn't find anything in ifconfig(8) to >do that. > >Then the second question would be: would net-snmp (daemon) actually be >looking at all the traffic? The reason I ask is because it appears that >traffic not destined for the NIC's MAC isn't shown to anyone but root. >Though I suppose that doesn't matter since the SNMP daemon is running as >root... > >TIA, >-- >wca >P.S. Please keep me on Cc:, I'm not subscribed to questions@. > >To Unsubscribe: send mail to majordomo@FreeBSD.org >with "unsubscribe freebsd-questions" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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