Date: Tue, 20 Feb 2001 23:37:44 -0800 (PST) From: Ken Lui <klui@cup.hp.com> To: Lowell Gilbert <lowell@world.std.com> Cc: freebsd-questions@freebsd.org Subject: Re: Question about arp for wakeonlan Message-ID: <Pine.HPX.4.10.10102202318420.6164-100000@hpcuhe.cup.hp.com> In-Reply-To: <rd6elwuvyin.fsf@world.std.com>
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On 19 Feb 2001, Lowell Gilbert wrote: > > So do I specify my local router's IP but my home PC's ethernet > > address? OK, I did this but I lost connection with my work machine. > > I'm unsure of how to set up a "proxy" entry in arp. > > Proxy arp is a terrible hack, and breaks the IP layering model > something fierce. Nonetheless, there are occasions when people find > it useful; however, those situations involve a router (which does the > proxying) which is directly connected to both the host for which the > router is proxying and the hosts receiving the proxy packets. It > doesn't sound like that's what's happening in your case, unless the > default router for your home machine is somehow the same machine as > the default router for your work machine. > > You indicated that you want to do wake-on-LAN, but that this only > works if the router has a current ARP entry for the machine you're > waking. This makes sense; the machine won't wake up on broadcasts, or > wake-on-LAN would never work at all, so the router has to be able to > do a unicast for the wake packet. This is only possible if the router > has an ARP mapping, so you're depending on the router keeping a valid > ARP entry for the host; if the host is sleeping, this is only possible > with a static entry in the router's ARP table. So you need to do the > ARP command on the router, not either of the end machines. > Alternatively, you could get another machine on the same link to send > the "wake" packet for you, and make sure that *it* has the static ARP > entry for the sleeping machine. > > I hope that this explanation is sufficient to get you going. If not, > it's likely that you simply don't have the access to be able to do > what you want. Lowell, Thanks for taking the time to explain arp to a network newbie like myself. Although your reply indicated that it will not work, I did get wake on LAN to work over the WAN even after the arp entry has expired on the (in my case Cisco) router. My two machines--both FreeBSD--are on different subnets connected by different routers using different netmasks. Once the arp entry expired, I could no longer wake my work machine (for example) from home via wakeonlan <URL:http://gsd.di.uminho.pt/jpo/software/wakeonlan/>. I then tried to add a proxy on my home system via the command: arp -s <home.router.internet.name> <work.pc.ethernet.address> pub I had to do this twice because the first time, I got the error of "cannot intuit interface index and type for <router.internet.address.com>". But when I issued the command a second time, the command was successful and I could use wakeonlan to wake up my work machine. I would speculate that issuing arp -s <work.router.internet.name> <home.pc.ethernet.address> pub followed by a wakeonlan command would wake my home PC from work. Regards, Ken To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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