Date: Tue, 20 Jul 1999 01:47:15 -0700 (PDT) From: Vincent Poy <vince@venus.GAIANET.NET> To: sthaug@nethelp.no Cc: modred@ns1.antisocial.net, leifn@neland.dk, freebsd-hackers@FreeBSD.ORG Subject: Re: poor ethernet performance? Message-ID: <Pine.BSF.4.05.9907200143520.331-100000@venus.GAIANET.NET> In-Reply-To: <690.932458378@verdi.nethelp.no>
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On Tue, 20 Jul 1999 sthaug@nethelp.no wrote: > > > You see the MAC of the switch's port. It's been too long since I've > > > played on a Catalyst... but what does 'sh arp' display? Any arp -> port > > > -> host correlations? Good luck... :) > > > > Even if it did show the arp of the actual host, it's useless if it > > doesn't show the IP of the device connected to it since how will one know > > what device is what. > > As long as the hosts are using TCP/IP to communicate, you should be able > to get the IP to MAC address mapping from the ARP table of any host (or > router) connected to the same segment. You may have to look at the ARP > tables from several hosts (or use a broadcast ping) to get all the > mappings. > > Isn't this rather obvious? That would only work if the machines are on the hub but if each device is on a dedicated port on the switch of it's own, it's not supposed to see the other machines... Atleast we can't see the other machines MAC with netstat -r in FreeBSD. > > > Yeah, I've noticed the 'sync-up time' takes quite awhile on a Catalyst > > > running 100Mbps. > > > > It's pretty fast... Just it seems like the switch by default isn't > > like as secure as they say it is. People on other ports can't still sniff > > packets on the LAN. > > Ciscos have a 30 second delay when you connect something to a switch port. > This is given by the spanning tree protocol. If you want this to go faster, > turn off the spanning tree protocol on that port (OK if you can guarantee > no loops in the network from that port). I think this is true with any switch that has the STP feature. > Not sure what you mean by "the switch by default isn't like as secure as > they say it is". A switch is a bridge, and will isolate traffic between > ports. However, broadcast (and in many cases multicast) traffic will be > sent on all ports. Also, if the MAC address tables on the switch fills > up, any traffic from a *new* MAC address will be sent on all ports. No idea but it seems like the people who sold the Cisco switches atleast claimed that each port is supposed to be secure to prevent packet sniffing by people on the other ports... Cheers, Vince - vince@MCESTATE.COM - vince@GAIANET.NET ________ __ ____ Unix Networking Operations - FreeBSD-Real Unix for Free / / / / | / |[__ ] GaiaNet Corporation - M & C Estate / / / / | / | __] ] Beverly Hills, California USA 90210 / / / / / |/ / | __] ] HongKong Stars/Gravis UltraSound Mailing Lists Admin /_/_/_/_/|___/|_|[____] To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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