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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!uunet!in1.uu.net!204.73.178.32!chippy.visi.com!news-out.visi.com!feed1.news.erols.com!news.nl.innet.net!INnl.net!feed1.news.innet.be!INbe.net!blue.news.pipex.net!pipex!stns.news.pipex.net!warm.news.pipex.net!pipex!hole.news.pipex.net!pipex!news.utell.co.uk!usenet From: brian@shift.utell.net (Brian Somers) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Multiple IP adresses with FreeBSD Date: 30 Apr 1997 10:21:20 GMT Organization: Awfulhak Ltd. Lines: 46 Message-ID: <5k76f0$p26@ui-gate.utell.co.uk> References: <5k2t8m$rtd$1@s3.iway.fr> <3366F46C.77AC@OntheNet.com.au> Reply-To: brian@awfulhak.org, brian@utell.co.uk NNTP-Posting-Host: shift.utell.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Newsreader: knews 0.9.8 Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:40010 In article <3366F46C.77AC@onthenet.com.au>, Tony Griffiths <tonyg@OntheNet.com.au> writes: > pierre revel wrote: > >> >> I suppose that I can make it with the directive 'alias' in ifconfig >> but it doesn't work... It is not a problem with apache, >> I'm just trying to 'ping' the server at multiple IP addresses. > > Alias' is the correct way of doing this. However, I don't think that > adding an alias IP address to an Ethernet interface actually tells the > box to respond to ARP requests. So if another host tries a 'ping' it > will not be able to determine the MAC address of the host with the alias > IP addresses! > >> >> If anybody has an experience of this problem, any help >> will be appreciated ! > > In all cases that I have come across, the host containing the alias IP > addresses is either the 'designated router' for the entire C-class, or > there is an explicit route in the default router which points off to the > target machine and all of the alias addresses are part of a sub-net that > is different to the main network on the LAN. (ie. hosts on the LAN don't > try to ARP but simply send to the default router which knowns to forward > the packet to the virtual Web server host via an explicit route). An arp is *always* done for machines deemed to be on the local segment: $ (ping -c1 ui-gate; ping -c1 auth)>/dev/null; arp -a | egrep ui-gate\|auth ui-gate.utell.net (97.0.0.89) at 0:0:c0:f2:e1:a1 auth.utell.net (97.3.0.1) at 0:0:c0:f2:e1:a1 $ rlogin ui-gate $ ifconfig ed1 ed1: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500 inet 97.0.0.89 netmask 0xff000000 broadcast 97.255.255.255 inet 97.3.0.1 netmask 0xffffffff broadcast 97.3.0.1 ether 00:00:c0:f2:e1:a1 > Tony -- Brian <brian@awfulhak.org> <brian@freebsd.org> <http://www.awfulhak.org> Don't _EVER_ lose your sense of humour !