ip=dhcp problem...

ip=dhcp problem...

[Charles-Henri Collin]

Hi,

I've got the following problem with linux 2.6.8.1:
I'm nfs-rooting a diskless client with kernel parameter ip=dhcp.
My dhcpd.conf  has a "option domain-name-servers X.X.X.X;" statement and 
"get-lease-hostnames true;"
Now when the diskless clients boot, no name-server configured and they 
cant resolv.
dmesg gives me, for instance:

IP Config: Complete:
    device=eth0, addr=192.168.0.237, mask=255.255.255.0, gw=192.168.0.1,
    host=clientFSB-237.fsb.net, domain=fsb.net, nis-domain=FSBnis,
    boot-server=192.168.0.254, rootserver=92.168.0.254, rootpath=

So as you can see, everything is almost set up, except a nameserver!
Has anyone heard about that problem before? Are there any fixes?

regards,
C COLLIN

Re: ip=dhcp problem...

[Andreas Unterkircher]

I don't think that the kernel take care about the nameservers during bootup.

On my debian system resolving is only working, after init takes control
over the system and the network scripts running the dhclient-script
which also sends an dhcp-request - and finally get the same ip - and
adds the nameservers into the resolv.conf.

regards,

Andreas


Charles-Henri Collin wrote:

> Hi,
>
> I've got the following problem with linux 2.6.8.1:
> I'm nfs-rooting a diskless client with kernel parameter ip=dhcp.
> My dhcpd.conf  has a "option domain-name-servers X.X.X.X;" statement 
> and "get-lease-hostnames true;"
> Now when the diskless clients boot, no name-server configured and they 
> cant resolv.
> dmesg gives me, for instance:
>
> IP Config: Complete:
>    device=eth0, addr=192.168.0.237, mask=255.255.255.0, gw=192.168.0.1,
>    host=clientFSB-237.fsb.net, domain=fsb.net, nis-domain=FSBnis,
>    boot-server=192.168.0.254, rootserver=92.168.0.254, rootpath=
>
> So as you can see, everything is almost set up, except a nameserver!
> Has anyone heard about that problem before? Are there any fixes?
>
> regards,
> C COLLIN
>
>
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Re: ip=dhcp problem...

[Jan Engelhardt]

>
> I've got the following problem with linux 2.6.8.1:
> I'm nfs-rooting a diskless client with kernel parameter ip=dhcp.
> My dhcpd.conf  has a "option domain-name-servers X.X.X.X;" statement and
> "get-lease-hostnames true;"
> Now when the diskless clients boot, no name-server configured and they cant
> resolv.
> dmesg gives me, for instance:

What happens if you put
	option domain-name-servers 192.168.222.1;
in your dhcpd.conf, i.e. an IP number rather than a host?




Jan Engelhardt
-- 
ENOSPC

Re: ip=dhcp problem...

[Charles-Henri Collin]

Jan Engelhardt a écrit :

>>I've got the following problem with linux 2.6.8.1:
>>I'm nfs-rooting a diskless client with kernel parameter ip=dhcp.
>>My dhcpd.conf  has a "option domain-name-servers X.X.X.X;" statement and
>>"get-lease-hostnames true;"
>>Now when the diskless clients boot, no name-server configured and they cant
>>resolv.
>>dmesg gives me, for instance:
>>    
>>
>
>What happens if you put
>	option domain-name-servers 192.168.222.1;
>in your dhcpd.conf, i.e. an IP number rather than a host?
>
>
>
>
>Jan Engelhardt
>  
>
i do put IP in this field (192.168.0.254) in fact, but this doesnt work.
i'm looking for a reason why it desnt work.. i've just setup:
#define  IPCONFIG_DEBUG
in linux/net/ipv4/ipconfig.c, and this is what i get at boottime:

DHCP:   Get message type 2
DHCP:   Offered address 192.168.0.237 by server 192.168.0.254
DHCP/BOOTP:    Got extension   53: 02
DHCP/BOOTP:    Got extension   54: c0 a8 00 fe
DHCP/BOOTP:    Got extension   51: 00 01 19 40
DHCP/BOOTP:    Got extension   1: ff ff ff 00
DHCP/BOOTP:    Got extension   3: c0 a8 00 fe
DHCP/BOOTP:    Got extension   12: 63 6c 69 65 6e 74 46 53 42 2d 32 33 
37 2e 66 73 62 2e 6e 65 74 00
DHCP/BOOTP:    Got extension   15: 66 73 62 2e 6e 65 74
DHCP/BOOTP:    Got extension   40: 46 53 42 6e 69 73
,DHCP:   sending message type 3
DHCP: Got message type 5
DHCP/BOOTP:    Got extension   53: 05
DHCP/BOOTP:    Got extension   54: c0 a8 00 fe
DHCP/BOOTP:    Got extension   51: 00 01 19 40
DHCP/BOOTP:    Got extension   1: ff ff ff 00
DHCP/BOOTP:    Got extension   3: c0 a8 00 fe
DHCP/BOOTP:    Got extension   12: 63 6c 69 65 6e 74 46 53 42 2d 32 33 
37 2e 66 73 62 2e 6e 65 74 00
DHCP/BOOTP:    Got extension   15: 66 73 62 2e 6e 65 74
DHCP/BOOTP:    Got extension   40: 46 53 42 6e 69 73

Extension 6 is the nameserver (see config.c for more details) and it is 
set as you can see. that is strange....
i'm looking for more hints. hope this will help.
regards,

C COLLIN

Re: ip=dhcp problem...

[Martin Josefsson]

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On Sat, 2004-12-18 at 11:15, Charles-Henri Collin wrote:
> Hi,
> 
> I've got the following problem with linux 2.6.8.1:
> I'm nfs-rooting a diskless client with kernel parameter ip=dhcp.
> My dhcpd.conf  has a "option domain-name-servers X.X.X.X;" statement and 
> "get-lease-hostnames true;"
> Now when the diskless clients boot, no name-server configured and they 
> cant resolv.
> dmesg gives me, for instance:
> 
> IP Config: Complete:
>     device=eth0, addr=192.168.0.237, mask=255.255.255.0, gw=192.168.0.1,
>     host=clientFSB-237.fsb.net, domain=fsb.net, nis-domain=FSBnis,
>     boot-server=192.168.0.254, rootserver=92.168.0.254, rootpath=
> 
> So as you can see, everything is almost set up, except a nameserver!
> Has anyone heard about that problem before? Are there any fixes?

The fix is to make sure you have a nameserver in your /etc/resolv.conf
The kernel has no idea how to resolve names into addresses. That's a
userspace thing. I'm not sure if you can extract the dhcp info from the
kernel after the boot, otherwise you'll just have to run a userspace
dhcp client, I use dhclient.

-- 
/Martin

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Re: ip=dhcp problem...

[Charles-Henri Collin]

Martin Josefsson a écrit :

>On Sat, 2004-12-18 at 11:15, Charles-Henri Collin wrote:
>  
>
>>Hi,
>>
>>I've got the following problem with linux 2.6.8.1:
>>I'm nfs-rooting a diskless client with kernel parameter ip=dhcp.
>>My dhcpd.conf  has a "option domain-name-servers X.X.X.X;" statement and 
>>"get-lease-hostnames true;"
>>Now when the diskless clients boot, no name-server configured and they 
>>cant resolv.
>>dmesg gives me, for instance:
>>
>>IP Config: Complete:
>>    device=eth0, addr=192.168.0.237, mask=255.255.255.0, gw=192.168.0.1,
>>    host=clientFSB-237.fsb.net, domain=fsb.net, nis-domain=FSBnis,
>>    boot-server=192.168.0.254, rootserver=92.168.0.254, rootpath=
>>
>>So as you can see, everything is almost set up, except a nameserver!
>>Has anyone heard about that problem before? Are there any fixes?
>>    
>>
>
>The fix is to make sure you have a nameserver in your /etc/resolv.conf
>The kernel has no idea how to resolve names into addresses. That's a
>userspace thing. I'm not sure if you can extract the dhcp info from the
>kernel after the boot, otherwise you'll just have to run a userspace
>dhcp client, I use dhclient.
>
>  
>
i should put a /etc/resolv.conf.... but i dont want, for "dark reasons" ;)
if i have a /etc/resolv.conf, what's the point in querying the dhcp 
server for a nameserver???
i thought this would set linux a nameserver in case no /etc/resolv.conf 
was find.
btw, i can't dhclient has i'm nfs-rooting. doing this breaks my 
connection with the nfs server and i lose / !!!!!
i'm working on it.
thanks anyway

regards,
 COLLIN

Re: ip=dhcp problem...

[Martin Josefsson]

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On Sat, 2004-12-18 at 13:10, Charles-Henri Collin wrote:

> >The fix is to make sure you have a nameserver in your /etc/resolv.conf
> >The kernel has no idea how to resolve names into addresses. That's a
> >userspace thing. I'm not sure if you can extract the dhcp info from the
> >kernel after the boot, otherwise you'll just have to run a userspace
> >dhcp client, I use dhclient.
> >
> >  
> >
> i should put a /etc/resolv.conf.... but i dont want, for "dark reasons" ;)
> if i have a /etc/resolv.conf, what's the point in querying the dhcp 
> server for a nameserver???
> i thought this would set linux a nameserver in case no /etc/resolv.conf 
> was find.
> btw, i can't dhclient has i'm nfs-rooting. doing this breaks my 
> connection with the nfs server and i lose / !!!!!
> i'm working on it.
> thanks anyway

I use FAI (http://www.informatik.uni-koeln.de/fai/) to install servers
here. They use ip=dhcp in order to have nfs-root, then they run dhclient
in order to get dns and to maintain the lease correctly (not sure the
kernel does this for you). I don't loose contact with the nfs server,
works just fine.

-- 
/Martin

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