[TriLUG] OT: getting dhcp client to pass hostname - iPod 2nd gen

Joseph Mack NA3T jmack at wm7d.net
Sat Mar 7 23:07:20 EST 2009


On Sat, 7 Mar 2009, Matt Pusateri wrote:

> So when more devices appear, I assume someone gives them 
> the WPA key?

my son, I don't even have to be around.

> I'm not really sure why it matters what device it is, it's 
> not like your probably trying to connect to the ipod(s) 
> from your computer?

There's no ports open, so you can't get in from the outside. 
I googled for getting a shell prompt on the iPod and you 
can't do that by default. You have to hack it and this 
hasn't been done for the current iPod. You can get a shell 
prompt on a DD-WRT, so why not on an iPod? Apparently Apple 
doesn't want people doing this. I would have thought at 
least port 22 would be listening ;-)

> Don't get me wrong, I agree it should behave courteously, 
> but I missing why it matters?

I don't like seeing dhcp leases for computers named NULL. 
Maybe it's just my view that if anything isn't working as 
it's supposed to, I should find out why.

There's more data since I first posted.

The name originally was "a-moose" which gave the NULL 
problem. I asked my son to change the name to "amoose", and 
dhcpd still showed "NULL", so I thought the iPod wasn't 
sending its name.

When trying to nmap the device by it's IP, I get back 
replies from "a_moose". To my surprise, I find the name 
"a_moose" is in the (dhcpd updated) DNS tables. The name in 
DNS can only come from dhcpd, so apparently the device has 
sent its name, which is output as NULL by dhcpd, but 
recorded as "a_moose" in DNS. It turns out my son had 
misunderstood my request and used "a moose" as the name. 
(He's not a *nix'er, and doesn't know that blanks are a 
problem in *nix names.)

It seems likely that the problem is munging the blank char 
or '-' char.. By the time it arrives at DNS the blank has 
been changed to a "_". I assume dhcpd barfs when trying to 
output a name with a blank or a '-'. The thing to do 
tomorrow is to get my son to change the name to "amoose".

Joe
-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!



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