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Re: [nslu2-general] Re: setting up backups in Windows

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  • Mike Westerhof
    You ll have no need of Static DHCP *IF* your XP laptop never goes anywhere. Consider what would happen if you were to take your XP laptop to which you ve
    Message 1 of 18 , Oct 4, 2005
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      You'll have no need of Static DHCP *IF* your XP laptop never goes anywhere.

      Consider what would happen if you were to take your XP laptop to which you've assigned the address 192.168.1.75 off to, for example, your place of business, or to a hotel with wired ethernet, and you wished to plug into the network. Since there is no reason to think that the IP address you have assigned to your laptop is valid on the other network, you need to find an administrator for the business or hotel network, and get an IP address valid for that network assigned for your use, and reconfigure your laptop to use that. More likely, you'll reconfigure your XP laptop to enable DHCP, so it can simply ask the new network for an IP address itself -- that's what DHCP does.

      Now once you return home, you can plug back into your home network. If, of course, you remember to re-configure your network settings to reassign 192.168.1.75 to the XP laptop. If you forget, your laptop will happily DHCP itself on your home network, and your network will give your laptop an available IP address out of the pool. You don't know which IP it assigned, so there's now no good way for your NSLU2 or many other devices to be able to reach out to your laptop and talk with it.

      Static DHCP allows you to instruct the DHCP server (in your case, the WRTG which unfortunately doesn't support this) that when it sees a request from your XP laptop for an IP address to *ALWAYS* assign it the same one (192.168.1.75). With this setup, you leave your XP laptop set up for DHCP always, it gets the same (well-known) IP address each time it connects to your home network, but when you plug in elsewhere, it gets whatever address it needs. No network configurations, no administrators required, no reboots, no hassles. It's a beautiful thing!

      Oh - I should also mention that DHCP can either provide a hostname for a computer, or if a computer has a hostname, the DHCP server can discover that fact as it assigns the new system its IP address. The WRTG, unfortunately again, doesn't do a blasted thing with this information. However, some other router/firewalls (and my unslung NSLU2, btw) integrate the DHCP service with the DNS service, so that when a system joins the network, it not only gets an IP address automatically, but it's host name automatically appears in the DNS database. Again, a thing of beauty, and with software packages like dnsmasq, amazingly simple to install and configure.

      (Don't get me wrong at all - I quite like the Linksys routers. They're very good at what they do, which is to provide the key network infrastructure for very simple, basic networks. What they lack, compared to (for example) the Motorola it competes with, are features that make it useful for more advanced networks. Static DHCP is one such feature. DNS caching is another. The other good thing about them is that they are common (read inexpensive), and can be easily "cracked open" and customized to suit the needs of the more advanced users.

      JMO.
      ~wester
      ----- Original Message -----
      From: Mark Hood
      To: nslu2-general@yahoogroups.com
      Sent: Tuesday, October 04, 2005 6:58 PM
      Subject: [nslu2-general] Re: setting up backups in Windows


      --- In nslu2-general@yahoogroups.com, Warren Gill <r2ml@f...> wrote:
      > If your router can do "static" DHCP, your laptop will
      > always get the same IP address from the DHCP server (you
      > link an IP in the "100" range to the MAC address of your
      > laptop). The standard Linksys firmware doesn't have this
      > option.

      I don't get this.

      When I log into the Linksys as admin through the web page
      served up by the standard Linksys firmware, it offers the
      ability to set a static IP in the Administration -> LAN
      tab. This is still available after the unslung process.

      I've always had my slug set up with a static private IP of
      192.168.1.77. Similarly I set up my XP laptop to always use
      192.168.1.75, and I don't have any problem making backups on
      my private network using the names I've mapped to these
      static IP addresses.

      My ISP gives me a static public IP from which I forward ssh
      and http ports through the router to the slug, so I can do
      backups using sftp or http from the external public internet
      if I need to.

      Most else on my network gets a dynamic IP served up by the
      DHCP running in my standard firmware Linksys WRT54G in the
      range 192.168.1.100 - 150.

      What the heck is "static" DHCP and why would one need it to
      run backups? I've never run across a device that doesn't
      allow you to set up a static IP.

      -- Mark


      [Non-text portions of this message have been removed]
    • Aaron Hoyt
      For this situation wouldn t be a cheap and simple alternative to use a separate USB network card? It seems you can get them for next to nothing lately, and
      Message 2 of 18 , Oct 5, 2005
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        For this situation wouldn't be a cheap and simple alternative to use a
        separate USB network card? It seems you can get them for next to nothing
        lately, and the second network card would have it's own settings. Set one
        to Static and use that to connect to the Local Network, use the second as
        DHCP and us it for connecting to any other network you visit.
        That way, you leave the second (DHCP) network card in your transport bag,
        and don't have to deal with the unassign/reassign for the static address on
        your home (static) card.
        Just a thought.

        -----Original Message-----
        From: nslu2-general@yahoogroups.com
        [mailto:nslu2-general@yahoogroups.com]On Behalf Of Mike Westerhof
        Sent: Tuesday, October 04, 2005 9:30 PM
        To: nslu2-general@yahoogroups.com
        Subject: Re: [nslu2-general] Re: setting up backups in Windows


        You'll have no need of Static DHCP *IF* your XP laptop never goes anywhere.

        Consider what would happen if you were to take your XP laptop to which
        you've assigned the address 192.168.1.75 off to, for example, your place of
        business, or to a hotel with wired ethernet, and you wished to plug into the
        network. Since there is no reason to think that the IP address you have
        assigned to your laptop is valid on the other network, you need to find an
        administrator for the business or hotel network, and get an IP address valid
        for that network assigned for your use, and reconfigure your laptop to use
        that. More likely, you'll reconfigure your XP laptop to enable DHCP, so it
        can simply ask the new network for an IP address itself -- that's what DHCP
        does.

        Now once you return home, you can plug back into your home network. If, of
        course, you remember to re-configure your network settings to reassign
        192.168.1.75 to the XP laptop. If you forget, your laptop will happily DHCP
        itself on your home network, and your network will give your laptop an
        available IP address out of the pool. You don't know which IP it assigned,
        so there's now no good way for your NSLU2 or many other devices to be able
        to reach out to your laptop and talk with it.

        Static DHCP allows you to instruct the DHCP server (in your case, the WRTG
        which unfortunately doesn't support this) that when it sees a request from
        your XP laptop for an IP address to *ALWAYS* assign it the same one
        (192.168.1.75). With this setup, you leave your XP laptop set up for DHCP
        always, it gets the same (well-known) IP address each time it connects to
        your home network, but when you plug in elsewhere, it gets whatever address
        it needs. No network configurations, no administrators required, no
        reboots, no hassles. It's a beautiful thing!

        Oh - I should also mention that DHCP can either provide a hostname for a
        computer, or if a computer has a hostname, the DHCP server can discover that
        fact as it assigns the new system its IP address. The WRTG, unfortunately
        again, doesn't do a blasted thing with this information. However, some
        other router/firewalls (and my unslung NSLU2, btw) integrate the DHCP
        service with the DNS service, so that when a system joins the network, it
        not only gets an IP address automatically, but it's host name automatically
        appears in the DNS database. Again, a thing of beauty, and with software
        packages like dnsmasq, amazingly simple to install and configure.

        (Don't get me wrong at all - I quite like the Linksys routers. They're very
        good at what they do, which is to provide the key network infrastructure for
        very simple, basic networks. What they lack, compared to (for example) the
        Motorola it competes with, are features that make it useful for more
        advanced networks. Static DHCP is one such feature. DNS caching is
        another. The other good thing about them is that they are common (read
        inexpensive), and can be easily "cracked open" and customized to suit the
        needs of the more advanced users.

        JMO.
        ~wester
        ----- Original Message -----
        From: Mark Hood
        To: nslu2-general@yahoogroups.com
        Sent: Tuesday, October 04, 2005 6:58 PM
        Subject: [nslu2-general] Re: setting up backups in Windows


        --- In nslu2-general@yahoogroups.com, Warren Gill <r2ml@f...> wrote:
        > If your router can do "static" DHCP, your laptop will
        > always get the same IP address from the DHCP server (you
        > link an IP in the "100" range to the MAC address of your
        > laptop). The standard Linksys firmware doesn't have this
        > option.

        I don't get this.

        When I log into the Linksys as admin through the web page
        served up by the standard Linksys firmware, it offers the
        ability to set a static IP in the Administration -> LAN
        tab. This is still available after the unslung process.

        I've always had my slug set up with a static private IP of
        192.168.1.77. Similarly I set up my XP laptop to always use
        192.168.1.75, and I don't have any problem making backups on
        my private network using the names I've mapped to these
        static IP addresses.

        My ISP gives me a static public IP from which I forward ssh
        and http ports through the router to the slug, so I can do
        backups using sftp or http from the external public internet
        if I need to.

        Most else on my network gets a dynamic IP served up by the
        DHCP running in my standard firmware Linksys WRT54G in the
        range 192.168.1.100 - 150.

        What the heck is "static" DHCP and why would one need it to
        run backups? I've never run across a device that doesn't
        allow you to set up a static IP.

        -- Mark


        [Non-text portions of this message have been removed]





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      • Mark Hood
        ... anywhere. Thanks for the info, that was interesting and useful. -- Mark
        Message 3 of 18 , Oct 5, 2005
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          --- In nslu2-general@yahoogroups.com, "Mike Westerhof" <mwester@d...>
          wrote:
          > You'll have no need of Static DHCP *IF* your XP laptop never goes
          anywhere.

          Thanks for the info, that was interesting and useful.

          -- Mark
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