* Question on DHCP
@ 2010-10-13 1:33 Sri Ram Vemulpali
2010-10-13 1:45 ` Stephen Hemminger
0 siblings, 1 reply; 3+ messages in thread
From: Sri Ram Vemulpali @ 2010-10-13 1:33 UTC (permalink / raw)
To: linux-netdev
Hi All,
I have very basic stupid doubt. Can anyone help to resolve this.
DHCP, is used for dynamically configuring IP address, mask, MTU, DNS
domain, .... for a host. DHCP is a application layer protocol, but the
values it configures are related to IP layer. How come DHCP can
configure when its data packet in embedded in to IP datagram, which
are disparate layers. I am little confused. Please clarify. Thanks.
--
Regards,
Sri.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Question on DHCP
2010-10-13 1:33 Question on DHCP Sri Ram Vemulpali
@ 2010-10-13 1:45 ` Stephen Hemminger
2010-10-13 7:31 ` Stefano Salsano
0 siblings, 1 reply; 3+ messages in thread
From: Stephen Hemminger @ 2010-10-13 1:45 UTC (permalink / raw)
To: Sri Ram Vemulpali; +Cc: linux-netdev
On Tue, 12 Oct 2010 21:33:25 -0400
Sri Ram Vemulpali <sri.ram.gmu06@gmail.com> wrote:
> Hi All,
>
> I have very basic stupid doubt. Can anyone help to resolve this.
>
> DHCP, is used for dynamically configuring IP address, mask, MTU, DNS
> domain, .... for a host. DHCP is a application layer protocol, but the
> values it configures are related to IP layer. How come DHCP can
> configure when its data packet in embedded in to IP datagram, which
> are disparate layers. I am little confused. Please clarify. Thanks.
>
DHCP client uses UDP to send broadcast packet and find the nearest
server. The Linux DHCP client ends up using a AF_PACKET socket because
it wants to seem MAC address of server.
--
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Question on DHCP
2010-10-13 1:45 ` Stephen Hemminger
@ 2010-10-13 7:31 ` Stefano Salsano
0 siblings, 0 replies; 3+ messages in thread
From: Stefano Salsano @ 2010-10-13 7:31 UTC (permalink / raw)
To: Stephen Hemminger, Sri Ram Vemulpali; +Cc: linux-netdev
Stephen Hemminger wrote:
> On Tue, 12 Oct 2010 21:33:25 -0400
> Sri Ram Vemulpali <sri.ram.gmu06@gmail.com> wrote:
>
>> Hi All,
>>
>> I have very basic stupid doubt. Can anyone help to resolve this.
>>
>> DHCP, is used for dynamically configuring IP address, mask, MTU, DNS
>> domain, .... for a host. DHCP is a application layer protocol, but the
>> values it configures are related to IP layer. How come DHCP can
>> configure when its data packet in embedded in to IP datagram, which
>> are disparate layers. I am little confused. Please clarify. Thanks.
>>
>
> DHCP client uses UDP to send broadcast packet and find the nearest
> server. The Linux DHCP client ends up using a AF_PACKET socket because
> it wants to seem MAC address of server.
you may also want to refer to RFC 2131 (Dynamic Host Configuration
Protocol), in section 2 it states:
In the case of a client using DHCP for initial configuration (before
the client's TCP/IP software has been completely configured), DHCP
requires creative use of the client's TCP/IP software and liberal
interpretation of RFC 1122. The TCP/IP software SHOULD accept and
forward to the IP layer any IP packets delivered to the client's
hardware address before the IP address is configured;
--
*******************************************************************
Stefano Salsano
Dipartimento Ingegneria Elettronica
Universita' di Roma "Tor Vergata"
Via del Politecnico, 1 - 00133 Roma - ITALY
http://netgroup.uniroma2.it/Stefano_Salsano/
E-mail : stefano.salsano@uniroma2.it
Cell. : +39 320 4307310
Office : (Tel.) +39 06 72597770 (Fax.) +39 06 72597435
*******************************************************************
^ permalink raw reply [flat|nested] 3+ messages in thread
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2010-10-13 1:45 ` Stephen Hemminger
2010-10-13 7:31 ` Stefano Salsano
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