I am the assigned Gen-ART reviewer for this draft. For background on
Gen-ART, please see the FAQ at
<http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
Please resolve these comments along with any other Last Call comments
you may receive.
Document: draft-sakane-dhc-dhcpv6-kdc-option-14.txt
Reviewer: Alexey Melnikov
Review Date: 23 March 2012
IETF LC End Date: 23 March 2012
IESG Telechat date: (if known) -
Summary: I think this document needs another revision before being ready
for IESG review, although I don't think that changes are difficult.
1. Introduction
To provide a set of IP addresses of the KDC, the Kerberos V5
specification [RFC4120] defines KDC discovery by utilizing DNS SRV
records [RFC2782]. However, systems that do not employ the DNS, but
do use DHCP, do exist, for example industrial systems. Some
industrial systems don't use DNS because they have already had their
own name spaces and their own name resolution systems, including pre-
configured mapping tables for devices, rather than using FQDNs and
DNS. And these systems would prefer not to employ DNS only for name
resolution because adding a new server may bring a decrease in the
reliability of the system, and increase the management cost of the
system.
Minor: I am a bit doubtful about this claim, but maybe this is just me.
Many systems already depend on DNS. However, I think you might be
missing out on showing another reason of why your extension might be
useful: it might eliminate some DNS lookups and thus can speed-up
acquisition of Kerberos credentials.
3.3. Kerberos Default Realm Name Option
This option provides a default realm name of the Kerberos system.
Unlike the Kerberos Realm Name Option, it is intended for a DHCPv6
server to use, and specifies the default realm name to both clients
and Kerberos application servers in the Kerberos system.
Major: Can you give me an example of when this option might be different
from the Kerberos Realm Name Option (section 3.2)?
3.4. Kerberos KDC Option
This option provides a set of configuration information about a KDC.
The format of the Kerberos KDC Option is:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_KRB_KDC | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Priority | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport Type| Port Number | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
| |
| KDC IPv6 address +---------------+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ :
: :
: realm-name :
: (variable length) :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Major: realm-name is not described later in this section. I think it
should be removed considering that you have 2 other options for Kerberos
realms already.
4. Client Operation
When the client requires configuration parameters for a Kerberos
system while bootstrapping, the client SHOULD put the client
principal name itself into the Kerberos Principal Name Option.
Minor: So this option is only ever sent from a DHCP client to a DHCP
server? Section 3.1 is not clear on that.
When the client requires specific information for a certain realm,
the client SHOULD specify the realm name in the Kerberos Realm Name
Option.
Minor: This might be answering one of my questions above, but I think
you should make this clear in Section 3.2.
When the client requires specific information related to a
certain Kerberos application server of the Kerberos system, the
client SHOULD put the principal name of the server into the Kerberos
Principal Name Option.
Major: Is such dual-purpose use a good idea?
4.1. KDC discovery for a client
1) Initially, the client asks both DNS and Kerberos information to
the DHCP server.
Nit: s/to/from
6) If, as the result of (1), if the client gets both DNS and Kerberos
information from the DHCP server, then the client asks Kerberos
information to the DNS server.
Nit: s/to/from
Minor: But this (or the diagram) looks confusing to me: if the client
already got both Kerberos and other information from DHCP, why should it
query DNS at all? I think either your diagram is confusing, or the
description below, or both.
5. Server Operation
After the DHCPv6 server receives a message which is contained an
Option Request Option, the information the server will provide
depends on local policy. If there are no criteria on the server, the
following operation is RECOMMENDED.
Nit: It is not entirely clear to me what you mean by "no criteria" above.
idnits reports a DownRef to RFC 6251, but this was called out during
IETF LC, so no problems here.
_______________________________________________
Gen-art mailing list
Gen-art@ietf.org
https://www.ietf.org/mailman/listinfo/gen-art
