RE: [nslu2-general] Re: setting up backups in Windows
- 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.
[mailto:email@example.com]On Behalf Of Mike Westerhof
Sent: Tuesday, October 04, 2005 9:30 PM
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
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.
----- Original Message -----
From: Mark Hood
Sent: Tuesday, October 04, 2005 6:58 PM
Subject: [nslu2-general] Re: setting up backups in Windows
--- In firstname.lastname@example.org, 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
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.
[Non-text portions of this message have been removed]
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- --- In email@example.com, "Mike Westerhof" <mwester@d...>
> You'll have no need of Static DHCP *IF* your XP laptop never goesanywhere.
Thanks for the info, that was interesting and useful.