Re: [dhcwg] What sorts of services does DHCP configure?

[Ted Lemon <[e-mail]>]

On Oct 15, 2013, at 9:41 AM, Reinaldo Penno (repenno) <[e-mail]> wrote:
> Would it make sense to determine which DHCP options are used today in wild
> and reasoning behind them?
> 
> I have done a few captures before and noticed that DHCP options vary
> between home, Hotel, Hotspot, Airport, etc.

It can't hurt to ask this question, but I'm not convinced that it's necessary.   DHCP clients don't use options they don't request, so it doesn't matter if the server sends them.   So it's probably not necessary to survey DHCP servers—just survey DHCP clients and see what options they request.

> As far as your SIP example below, I see SIP server through DHCP just as a
> discovery step. Your SIP client should apply whatever security policies to
> accept or not that SIP Server.

Right, but going a little farther into your example, this only works for clients that (a) request the SIP option and (b) have some way of validating the response they get back.   So we can have a very clear discussion about this security model, and also possibly ask whether existing clients actually do this, and whether this is a good idea, or just the best we could do with what services are available.

And then this question can be asked about lots of other services as well.  E.g., does it make sense to configure NTP this way, given that NTP provides replay protection for security protocols (that's a complicated question)?   Does it make sense to configure SMTP this way, given that SMTP servers are no longer really interchangeable as they were in the early days of the Internet?   POP?   IMAP?   Etc.