NSLU2 Debian Installer Erroneous asking for an IP address

[Sam Reed]

Whenever the NSLU2 is set to a static IP of 192.168.1.77, and then flashed it with the debian installer image, it is requesting an IP addresses from DHCP erroneously. Ie it is not following the static ip address (which is the Linksys default). Set to 192.168.1.78, and it uses the static IP address

 

 

(Martin, this is related to that email from before i sent you)

 

 

Sam

 

 

 

<mwester> I changed my static IP to 192.168.1.77, and it DHCP'd for some very odd reason. 

<Reedy_Boy> :S

<bearbear1982> hehe

<bearbear1982> ok

<Reedy_Boy> Sounds like a bug to me

<bearbear1982> tht solve my problem

<bearbear1982> tnx for the help

<mwester> Yeah, somebody needs to alert the debian folks of that problem. 

<Reedy_Boy> I'll post it if you want...

<mwester> (it may be more complicated than just that, but it definitely DHCP'd when I told it to do static, and stopped DHCPing when I changed the IP to 192.168.1.78)

<Reedy_Boy> Its recieving IP address from DHCP rather than the statically assigend one

<mwester> Well, more than just receiving, it's erroneously asking.

<Reedy_Boy> mwester, maybe so, but it gives martin/others a reasonable starting point

<Reedy_Boy> so on a statically assigned IP of 1.77 its dhcp'ing, anything else statically assigned its fine?

<mwester> That's true.  It's very possible that they missed it because they set up their routers to issue the 192.168.1.77 IP to that MAC address via DHCP.

<Reedy_Boy> hmm

<Reedy_Boy> Presumably, they wont have set it up to purposely ask for an ip if its already on the "default"

<mwester> That's how I set up my network as well; it saves a lot of time when testing.

<Reedy_Boy> i be

<Reedy_Boy> bet

<Reedy_Boy> just incase it went awol on IP's, dhcp puts it back on track?

<mwester> That way you test DHCP and static, but your NSLU2 is always at the same address, so you never lose it.

[Rod Whitby]

Sam Reed wrote:
> Whenever the NSLU2 is set to a static IP of 192.168.1.77, and then
> flashed it with the debian installer image, it is requesting an IP
> addresses from DHCP erroneously. Ie it is not following the static ip
> address (which is the Linksys default). Set to 192.168.1.78, and it uses
> the static IP address

My understanding is that this is the intended behaviour of the nslu2
debian installer network configuration logic.

(I'm not involved in that code, so Martin would know for sure).

-- Rod

--
To UNSUBSCRIBE, email to debian-ar...@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listm...@lists.debian.org

[Sam Reed]

Hmm

I did wonder that, but can't remember if I suggested it in the IRC channel

Not sure if it's actually noted anywhere then...

Sam

[Martin Michlmayr]

* Sam Reed <s...@piloting.fsnet.co.uk> [2008-01-07 23:57]:

> I did wonder that, but can't remember if I suggested it in the IRC channel
>
> Not sure if it's actually noted anywhere then...

I was going to say it's documented in my install guide, but I just
read it again and it's not clear. I'll clarify it later.
--
Martin Michlmayr
http://www.cyrius.com/

[Martin Michlmayr]

* Rod Whitby <r...@whitby.id.au> [2008-01-08 10:03]:

> > Whenever the NSLU2 is set to a static IP of 192.168.1.77, and then
> > flashed it with the debian installer image, it is requesting an IP
> > addresses from DHCP erroneously. Ie it is not following the static ip
> > address (which is the Linksys default). Set to 192.168.1.78, and it uses
> > the static IP address
> My understanding is that this is the intended behaviour of the nslu2
> debian installer network configuration logic.

That's correct.

The rationale behind it is in case the IP address is 192.168.1.77 you
didn't configure it explicitly, so maybe you really want another
address. That's why DHCP is used in this case.

That's the way the installer currently works, but I'm definitely not
saying it has to stay like this. If people find it confusing and have
the installer rather use the static address 192.168.1.77 in this case,
I can change the logic.

--
Martin Michlmayr
http://www.cyrius.com/

[Mike (mwester)]

So, basically even though the user has specified a static IP, the unit
DHCP's anyway. Considering that a well-behaved DHCP server will probe the
active addresses, it's *guaranteed* that not even by accident will the NSLU2
get the static IP that the user set. Hence the device is "lost on the
ether".

Debugging this situation is difficult for the novice. First, the user set a
static IP -- there's no reason for them to go check their router to see if
it issued a DHCP IP in the first place; they're not expecting that to
happen. Secondly, many routers don't even provide a means to check what
DHCP has done, so the user can't discover the IP even if a wiki or document
told them to do so (I believe that Linksys, one of the most common routers
in this area, is one such vendor).

Personally, I find this behavior of the installer to be wrong, in the same
way that I would be angry if my automobile took it upon itself to turn the
steering wheel for me, because I happened to leave the turn-signal activated
for too long. But I'm not a Debian user (I just happen to frequent the
#nslu2-general IRC channel where this issue has become so commonly asked).

IMO, if this behavior is retained, it needs a gigantic red box (flashing,
preferably) on the web pages describing the installation process. Many of
the users I encounter on that IRC channel are truely novices, so the text
also should not just limit itself to outlining the behavior, but the
implications of it as well (that the unit will DHCP and that many users may
not have routers that offer the ability to see what the DHCP IP might have
been, resulting in an NLSU2 on the network that is well and truely lost).
And, no, running nmap to find it is not an option for most of these users!

Regards,
Mike (mwester)

[Dirk Vanden Boer]

A simple workaround for people having problem with this. Wait to
plug-in the network cable until the slug finished booting. It will
fail to get a dhcp address and will fallback to static ip.

Greets

[Martin Michlmayr]

Sorry it took so long, but I've finally made that change. It will go
into the next release of Debian (lenny).

oldsys-preseed (2.0) unstable; urgency=low
.
* Use a static IP address when the configuration says so, even when
this is the default value used by the original firmware. In the
past, oldsys-preseed would do DHCP in the assumption that the user
never configured the static IP address and might not want to have
that setting. However, Mike (mwester) convinced me with his
argument in http://lists.debian.org/debian-arm/2008/01/msg00050.html
that doing DHCP when the configuration clearly says to use a static
IP is a bad idea.
* Increase the version number to 2.0 because of this change in
behaviour. This change affects Linksys NSLU2 and Thecus N2100.

* Mike (mwester) <mwe...@dls.net> [2008-01-08 12:49]:

--
Martin Michlmayr
http://www.cyrius.com/