[syslinux] PXEboot: can't find configfile on tftpd server

[Geert Stappers]

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On Mon, Sep 26, 2005 at 09:20:29AM -0700, H. Peter Anvin wrote:
> Cristi Mitrana wrote:
> >
> > You've got bitten by the dhcpd upgrade:
> > http://wiki.ltsp.org/twiki/bin/view/Ltsp/DhcpdSiaddr
> >basically, from 3.0.3  ISC dhcpd does not provide by default the
> >'next-server' address
> >which was (until this version) filled in with the dhcpd server address.
> >
> 
> Looks like it's time to add a test for a zero server field and 
> substitute the DHCP server address.  Sigh.

Please implement another algoritme.

IMNSHO it is not wise to modify a client due a server improvement.
( Yes, I consider the change done by ISC a good thing. ;-)


On the Etherboot mailinglist wrote Jim McQuillan
( http://sourceforge.net/mailarchive/message.php?msg_id=12947761 )

| I've had a dialog with David Hankins of ISC, and he pointed out that the
| intended behaviour of a dhcp client should be, if a netbooting client
| gets an offer that has a siaddr field of zeros, then it should ignore
| that offer and hope for a better offer from another dhcp server.

That approach allows having having multiple DHCP server on the network.
( one for Internet access and another DHCP server for netbooting. )


The RFC says
( http://www.faqs.org/rfcs/rfc2131.html )

| DHCP clarifies the interpretation of the 'siaddr' field as the
| address of the server to use in the next step of the client's
| bootstrap process.  A DHCP server may return its own address in the
| 'siaddr' field, if the server is prepared to supply the next
| bootstrap service (e.g., delivery of an operating system executable
| image).  A DHCP server always returns its own address in the 'server
| identifier' option.

Compressed into:  may return own addres _if_ prepared for the next part.


ISC is right to defaulting to 0.0.0.0, it is wrong to assume
that the DHCP server configuration that came just out of the box
has also a TFTP server configured.

When sysadmins add next-server to dhcpd.conf they tell
what the actual situation is: Where the TFTP server is
( is it is really present )


> Looks like it's time to add a test for a zero server field and 
> substitute the DHCP server address.  Sigh.

Or educate sysadmins


St

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