Date: Thu, 13 Aug 1998 12:33:02 -0700 (PDT) From: Doug White <dwhite@resnet.uoregon.edu> To: Peter Haight <psh1@cornell.edu> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Setting up two way PPP connection. Message-ID: <Pine.BSF.4.00.9808131228410.11633-100000@resnet.uoregon.edu> In-Reply-To: <199808120739.AAA07324@wartch.sapros.com>
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On Wed, 12 Aug 1998, Peter Haight wrote: > >Your ISP will do that? That usually costs them mega-bucks. > > Well, this is all a centrex ISDN thing, so maybe it is cheaper than with > modems. Anyway, I hacked the user-level ppp guy to handle this situation. It > now listens for RINGs on the ISDN TA as well as watching for packets on > the tun device. So that problem is solved. Okay, so it's tricky. ;) > >> 2. The ISP has given me an 8 IP subnet. Their router routes all packets to > >> one address which is the other end of the PPP line. In order to do this I > >> had to use two IP addresses for my router. One was the IP address on the > >> local lan and the other is the one it gets from the PPP line. Is there some > >> way to avoid this? Can I set the PPP link up as some kind of bridge instead? > > > >No, ppp doesn't support bridging. You'll have to work it so both ends get > >the same IP regardless. Then you can config pppd to give the remote the > >IP it normally gets when you dial in. > > I'm not following you. I'll try and explain better. > > Normally my network is 10.0.0.0/29. I configure my router to have the IP > 10.0.0.1. I gave the other machine on the network 10.0.0.2. Both of them > have netmasks of 255.255.255.248. At this point I can ping everyone and > everyone is happy. > > Now I dial into my ISP. I tell my ISP that I want to use 10.0.0.1 as my IP. > It says OK and that the gateway is 10.0.2.21. Now ppp does the following: > > It creates the tun0 device with IP 10.0.0.1. It then makes 10.0.2.21 the > default route. > > Now when I try to ping 10.0.0.2 it doesn't work. The reason (I think) > is that the routing table says to route anything in the 10.0.0.0/29 > subnet through 10.0.0.1. At this point both ed0 and tun0 have 10.0.0.1 > as their inet address. I'm not exactly sure what FreeBSD decides to do > in this situation, but it doesn't work. I can ping any host out on the > Internet at this point, though. Okay, this is the problem. FreeBSD doesn't allow two interfaces to have the same IP address. You need to change ed0's ip to something else. > I thought I could fix this by adding ADD 0 0 INTERFACE to the ppp.linkup > file, but whenever I try to send a packet to the Internet in this mode, I > get an error like "Address family not supported". If I look at the routing > table, the default route is to tun0 and there is no IP address specified. > Do I just need to use two IP addresses for the router or is there something > I'm missing? Yeah, you're going to have to use two -- one for each interface. Doug White | University of Oregon Internet: dwhite@resnet.uoregon.edu | Residence Networking Assistant http://gladstone.uoregon.edu/~dwhite | Computer Science Major To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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