DHCP Question
2007-12-25 11:16:00
accurately,
the results aren't quite what one expects. So, the burden is mine to
be more accurate.
Thanks to all, but:
a. I know what DHCP means and is.
b. I know what DNS is.
What I am looking for is a means by which my NIS+ database
(hosts.org_dir)
is updated when a DHCP request is responded to. The dhcpconfig even
alludes to the fact that DHCP will update the NIS+ database when it
passes
out an IP address, but it doesn't! Sun acknowledges this problem - and
my
SO is now part of a general Enhance Request for DHCP to update NIS+
database (the response from Sun will be the end of this summary).
The reason I don't want to use DNS is:
a. my internal network space is unregistered and unknown to the DNS
world
in general - and I want to keep it that way. I use Network Address
Translation
and my external DNS is way different and seperate from my internal
space!
Besides, I don't want my host names known to the external world for
security
reasons.
b. I don't want to have to set up two different DNS spaces, one
un-regestered
internal, and a second for registered external!
I want my host to ip mapping internally to be done by NIS+. Yes, wins
is a
solution and works, but there are two unix host to ip mappings which are
needed
and wins won't satisfy this. One is critical - Solstice backup (aka
Legato Networker)
uses host names only and depends on NIS+ to resolve the ip address.
Without
this mapping, this backup fails! The other mapping is one of ease -
when running
x-windows on a pc - which we do often, it is easier to specify a pc name
than
an ip address.
There were a couple of suggestions which indicate that DHCP will update
a dynamic
DNS - but I want DHCP to update NIS+. So, I have to wait for Sun to do
this - which
they indicate they will *sometime*. In the mean time, I'm stuck with
administering
pc clients with NIS+ and Solstice with fixed ip addresses.
The replies I received:
--------------------------------------------------------------------------------------
:
Marc Summers <marcs@eluminant.com>
You want to go to docs.sun.com and check out the documentation
on DHCP, you can do a search, or look up under solaris 7 documentation
and find all you ever wanted to know about DHCP and then some.
--------------------------------------------------------------------------------------
"Matthew Stier" <Matthew.Stier@tddny.fujitsu.com>
The DHCP protocol is as it's name implies. A "Dynamic Host
Configuration
Protocol". It is for the configuration of Hosts, not Servers?
Even Microsoft doesn't tie DHCP and WINS together. It may seem like it,
but what is really happening, is that the client gets configured through
DHCP and then announces itself, and it is those announcements that
update
WINS.
Now to be fair, there is a Dynamic DNS implementation available, which
can
be tied into most implementations of DHCP to obtain what you want; and I
believe Solaris 8 will ship with this.
--------------------------------------------------------------------------------------
"Jonathon W. Ross" <jonathon@debian.org>
Yes.
You are missing what DHCP is :)
Dynamic *HOST* Configuration Protocol.
JWR
--------------------------------------------------------------------------------------
Gwynne, Alun P" <Alun.Gwynne@capgemini.co.uk
Hi Matt,
I wonder if you are confusing WINS, DNS and DHCP ? DHCP is for farming
out
IP configurations - addresses, gateways etc. It doesn't maintain a name
service.
DHCP doesn't tell every client what name it should have, since they will
usually have names already. It gets a request from a hardware address,
and
issues the dynamic details. The only way that the issued details get
registered anywhere is with a dynamic name service like WINS or the
fairly
new Dynamic DNS.
When your Win98 (or any windows) client loads, it has to actively
register
itself with WINS. This is a flat namespace, belonging only to MS
clients.
If you want to register with a "proper" name service, you would have to
have
some software that detects what's going on, then dynamically updates the
name service. This is the gist of DDNS, but I haven't looked at NIS.
Regards,
Alun
--------------------------------------------------------------------------------------
Peter Watkins <peter@jrc.nl>
Yes, I hit this as well and have yet to find a sensible solution.
So if you find one I'll be grateful for any more information. In
fact I think this is a serious problem if you use Sendmail for
your email and have invoked the anti-third party relaying features.
In this case the sendmail tries to do a IP lookup on the connecting
PC and if it doesn't find a correct result promptly rejects the
connection. Naturally with DHCP running this is prone to fail!!!
Reading the literature I believe that hostname CAN be passed by
DHCP but not in a very straightforward manner. I'm still looking
at that.
I think that for the lookup problem what you need to do is put
your complete DHCP IP range into DNS/NIS/NIS+ with corresponding
hostnames. Then the lookup will always return the same hostname
for a given IP number. Which is what you want. It remains unclear
to me what hostname the client actually reports and whether this
is actually relevant.
Peter Watkins
--------------------------------------------------------------------------------------
"Shoshana B. Billik" <shoshana@nas.nasa.gov>
Hi, Matt! Thanks for your message, which you sent to the
Sun-Managers
mailing list, about DHCP.
I'm a newbie to this list, so I may not know what I'm talking
about
here, but it seems to me that it isn't the role of DHCP to provide IP
address
to hostname resolution; rather, I would think this service would be
provided by
NIS/NIS+ and/or DNS. I'm therefore wondering if the problem lies with
the
setup of the NIS+ server rather than with the DHCP server.
I'll be curious to hear what answers others come up with. Take
care.
--Shoshana
--------------------------------------------------------------------------------------
Alan Orndorff <dwarfie@mindspring.com>
Microsoft's answer to this problem was WINS. Have you thought about
going to www.isc.org and grabbing DHCP and DDNS from them and
setting it up?
alan
--------------------------------------------------------------------------------------
Nate Itkin ~ <Nate-Itkin@ptdcs2.ra.intel.com>
DHCP is useful for laptops, diskless systems, and roving devices. It
allows someone to easily obtain an ip address on a short term basis.
A smart client (Solaris for example, but not M$ Windoze) can also
acquire
a hostname from DHCP as well as a laundry list of other useful
information
such as the ip address of netbios name server(s), the netmask, broadcast
address, default router, and so on. However, you still need to create
an
entry in the DNS and or NIS host table for each leased IP address (if
you
desire to have the forward name-to-ip mapping work). I guess the best
way
to think about DHCP is like BOOTP because that's really what DHCP is -
BOOTP
plus enhancements.
You might want to investigate the latest and greatest version of BIND.
It may offer some native DHCP support. I know it has been a topic of
discussion, but I don't know if anything has been done.
--
- Nate Itkin
--------------------------------------------------------------------------------------
"Darryl C. Price" <darryl@mirapoint.com>
My apologies in advance for the simplicity of this response. My intent
most certainly is not to condescend, but ping and other tcp and udp
applications still have to make calls to the resolver library to
resolve the address. The purpose of DHCP is not to supplant DNS or NIS
for name resolution. Its purpose is to eliminate some of the complexity
of managing your namespace via reusable dynamically allocated
address/hostnames. If you have some fixed number of addresses you
intend to dynamically assign you can define them in advance (DNS, NIS,
etc ...) and never have to worry about them again. You DHCP server need
only maintain a database of available addresses in the address pool.
--Darryl
--------------------------------------------------------------------------------------
Arthur Darren Dunham <add@netcom.com>
DHCP is for many things. The main thing is providing a MAC address to
IP address mapping. NT relies heavily on NT naming via WINS. The
Microsoft NT DHCP server integrates these two items.
Most UNIX names are distributed via DNS. DNS is distributed and cached,
so fast updates from a single server are difficult.
There are some projects to attempt to make DNS and DHCP work together
more closely, but those are in development.
If you need dynamic naming with the Sun DHCP server, you'd have to add
on some scripts of your own to populate whatever naming scheme you're
using (NIS/NIS+/DNS).
--------------------------------------------------------------------------------------
"David Evans" <DJEVANS@au.oracle.com>
DHCP allows _dynamic_ allocation of an IP address to an NIC address.
This can then be allocated to another card when the first machine
if finished with it (normally off-line or turned off). So hostname is
not relevant except on the client end. The IP issued may not be the
same each time. If you are only issuing the one IP address what are
you doing run DHCP when a static is all that is required?
If you want to ping on hostname you need a _static_ IP.
I think you need to do some reading on DHCP and DNS. You seem to have
the concepts slightly bent.
I'd give some pointers to the DHCP and DNS material but that area is not
my forte. Maybe your summary could contain a few pointers.
Hope this helps,
David Evans
--------------------------------------------------------------------------------------
Erwin Fritz <efritz@GLJA.com>
DHCP is for IP address management, not host name resolution. If you want
host name resolution on Solaris, look at DNS. I don't know whether Sun's
DNS integrates with Sun's DHCP, though.
--------------------------------------------------------------------------------------
Sun Response:
Hi Matt,
It looks like Sun's DHCP server currently doesn't have
the functionality of dynamically updating the database
(either through NIS+ or files) with the hostname
of DHCP client. You would have to associate the IP
address with a hostname and choose this option within
the setup of the DHCP server to currently work around this.
There have been many bugs filed against this issue, most
closed as a duplicate of bug #4006121. I have added
you to this bug. There's not much that can be done at this
point other than waiting for the fix. These bugs have been
filed as RFE's (Request for enhancement) because the DHCP
server is following the RFC standard.
If you have any questions or need clarification, let me know.
I'll leave this service order open through end of week (10/22).
Thanks,
Kim McNeill (510) 574-8585
Sun Enterprise Services
Here's the bug report:
Bug Id: 4006121
Product: sunos
Category: network
Subcategory: dhcp_server
Bug/Rfe/Eou: rfe
Synopsis: We should add ability to have dhcp daemon update hosts
information
(optionally)
Description:
When DNS dynamic update becomes available in Solaris, the in.dhcpd
should be
modified to allow update of the hosts tables (thru xfn), and thus update
files,
dns, or nisplus.
Example of other bugs filed:
Bug #4086938 (Synopsis: RFE to allow dhcp servers to update DNS/NIS+
with names
from dhcp clients)
This issue is closed as a duplicate of the above bug #4006121.
=============================================================
Thanks to everyone for their replys!
Matt Reynolds
--
Matt Reynolds Matt.Reynolds@aztek-eng.com
IS/Network Manager V:303-415-6166
Aztek Engineering, Inc. F:303-786-9190
2477 55th St. www.aztek-eng.com
Boulder, CO 80301
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