Re: SMTP option for DHCPv6

On 5/27/2005 5:04 AM, Cristian Cadar wrote:

> There is already a standardized SMTP option for DHCPv4. My question is:
> Do you know any implementation where SMTP option is used by somebody for
> delegating IPv4 SMTP server addresses to the clients? do you think that
> the SMTP option for DHCPv6 will be used in the future by the email
> clients?

The short answer is no.

The long answer consists of multiple parts. For one thing, most of the
client DHCP stacks are not integrated with application software very well.
About the best you can expect (and this isn't very good) is for the DHCP
client to overwrite config data for an application (like updating a
mail.conf file that it has been told about). Very few applications
actually make DHCP calls themselves, and in some cases this isn't even
possible because the DHCP client has bound to the ports and is preventing
the applications from making their own requests.

Another point of difficulty here is that DHCP is mostly geared towards
"host configuration" and not to "user-specific configuration". This has
some security implications in application layer software--you may not want
anonymous guest users using your mail server, or your mail server may
require authentication (which won't work with guests), etc.

Along the same lines, mail sessions are keyed to user identity, and user
identity is independent of the current network topology, while DHCP is
focused on topology identity.

Having said all of that, defining the option could still be useful and the
work should be done. But I wouldn't expect it to be used except in the
minor subset of instances where the above factors coincide with actual
installation considerations.

-- 
Eric A. Hall                                        http://www.ehsco.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/