Date: Fri, 09 Sep 2005 14:14:37 -0500 From: Greg Barniskis <nalists@scls.lib.wi.us> To: deltaski@earthlink.net Cc: freebsd-questions@freebsd.org Subject: Re: Home Network Setup Problem Message-ID: <4321DF1D.1040803@scls.lib.wi.us> In-Reply-To: <200509091120.36432.deltaski@earthlink.net> References: <200509090939.47357.deltaski@earthlink.net> <4321A1AE.80802@scls.lib.wi.us> <200509091120.36432.deltaski@earthlink.net>
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deltaski@earthlink.net wrote: >>Is it a switch, is it a router, or is it really both (high end >>thingy like Cisco 35xx?). Probably it is just a plain old switch >>with no routing capabilities. To avoid confusion, you should call it >>what it is. >> > > Oh my, sorry. It is an 8-port 10/100Mbps Ethernet Switch! How does that change > anything? It really doesn't (you don't want a router in that location, you want a switch). A router connects multiple IP subnets that otherwise cannot talk to one another. Turning on the gateway feature on your FreeBSD box makes it a two-interface router. A switch merely multiplexes packets on many ports (it's a signal repeater/amplifier). [snip] > Oh, my sorry! Yes, the default gateway is set and I have no firewall to > complicate matters. Ah... I see the problem now. You *MUST* do NAT on your BSD gateway, unless you personally control the configuration of your DSL router and can give it the necessary routing instructions to find your 172 network. You are trying to ping your DSL router from a private network address that the router does not know about. The ping will reach the DSL router and it will not know where to send the reply because your private address does not (cannot) exist in its routing table. So, it sends the reply on its default route, which is towards the Internet. Bye, bye ping reply! Again, this is just very basic networking stuff. I didn't see it before because I route packets between private networks all the time and it works -- the difference is that all my routers are well-informed about the pathways to all nearby networks. For the background information you need to know, buy this or find it at your local library: http://www.oreilly.com/catalog/tcp3/ I'm sure there are other and even better titles. -- Greg Barniskis, Computer Systems Integrator South Central Library System (SCLS) Library Interchange Network (LINK) <gregb at scls.lib.wi.us>, (608) 266-6348
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