On Thu, 2011-06-16 at 13:00 +0200, Timothy Murphy wrote: > Who decides the IP address of a device? The DCHP server. And if it considers that 192.168.1 and 192.168.2 are the same network, because its netmask puts the boundary at 192.168, you may have lots of fun and games. > 2) I also had a problem with the default gateway, > but this is more a matter of understanding an elementary networking issue. > I guess what I need is a short primer on networking for simpletons. > Is there anything along those lines online? Have you searched the Linux documentation project website? > Suppose machine A has default gateway machine B, > and suppose machine B has default gateway machine C. > Now suppose that on machine A I ping, or ssh to, an address not on the LAN. > Shouldn't this go to machine B, and then automatically get forwarded to C? Theoretically, yes. So long as the netmask and IP address combinations show that the address is foreign. And so long as IP forwarding is enabled on all the machines the traffic goes *through* (IP forwarding is not enabled on the client behind all the gateways). > Concretely, > my laptop 192.168.2.7 has default gateway 192.168.2.2 (a desktop) > and the desktop has default gateway 192.168.1.254 (my ADSL modem/router). > It seems to me that if I now ping www.google.co.uk (for example) > this should go to the internet and be responded to by google. > But it doesn't seem to be. Try some other addresses. Perhaps google.co.uk doesn't respond to pings. Or, what happens when you try pinging it while on the gateway computer? > Incidentally, someone (I guess NM) keeps emptying my /etc/resolv.conf . > However, I fill it up each time. Did you say how you set it? If you're putting overrides into the NetworkManager configuration, then I'd expect them to get entered into the resolv.conf file, when NetworkManager brings the interface up. If you're simply bodging them into the resolv.conf file, then I expect them to be lost. > Incidentally, I notice that my laptop, running Fedora-15, > seems to behave slightly differently to my desktop, running CentOS-5.6 , > Changes to the routing table on the latter, eg changing the default gateway, > do not seem to come into force until I re-boot. How are you trying to bring about the gateway change? Are you bringing its interface down and back up again, to force a configuration reload? To be honest, my opinion about NetworkManager is thus: You'd only use it on clients. All servers and gateways would have manually set network configurations, and be using the old network service. -- [tim@localhost ~]$ uname -r 2.6.27.25-78.2.56.fc9.i686 Don't send private replies to my address, the mailbox is ignored. I read messages from the public lists. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
