Re: [port-srv-reg] "xmp" service type and the unified IANA Service Name and Port Number Registry

[Joe Touch <[e-mail]>]

On 8/25/2011 5:33 PM, Stuart Cheshire wrote:
> On 25 Aug, 2011, at 11:06, Joe Touch wrote:
>
>> if SRV records were used *today* for all services, it would be a
>> requirement that the SRV tables on the local machine would need to
>> include a copy of entries from the ports table - i.e., it would need
>> to effectively replicate /etc/services anyway
>
> Joe, I'm not sure you understand how SRV records work. DNS SRV records
> are not "tables on the local machine" -- just like DNS address records
> are not "tables on the local machine" that replicate what would have
> been in that machine's old /etc/hosts file.

If you start a service, you need to register it somewhere. If you run a 
DNS somewhere else, you can register it there. Absent that, you need to 
register it on a DNS local to that machine (which I had assumed, since 
I've rarely had a machine that could control any entries in the DNS it 
got its name from).

>> getservbyname() is used both by clients and servers. A server that
>> doesn't consult a local /etc/services ... is basically saying it
>> cannot be reached by legacy clients in the Internet.
>
> Apple hasn't updated /etc/services since 2002, and yet... and yet...
> people somehow are managing to continue shipping new network software on
> it at an astonishing rate.

Many other manufacturers deploy both OS's and network software without 
Bonjour as well, and yet somehow apps keep running at the same 
astonishing rate. Is that an indication we don't need SRV records either?

 > How could that be? Is it possible that they
> just bind to the numeric port number IANA assigned to them, instead of
> sitting on their hands and waiting for the OS vendor to ship an update
> (and for all their customers to upgrade) before shipping their products?

They *have* to if they use your system, because you MADE them. Not 
because they wanted to, necessarily.

> Taking a dependency on /etc/services being updated would be disastrous
> for any software you were actually trying to ship to users.

It certainly would on an Apple. Good to know.

Joe