Subject: Re: [v6tc] Issue 2: service discovery: automatic or manual?

From: "Miguel Angel Diaz" <[email-masked]>
Date: Wed, 19 Jan 2005 09:30:34 +0100

> On Tue, 2005-01-18 at 03:18 -0800, Alain Durand wrote:
>> On Jan 18, 2005, at 2:39 AM, Miguel Angel Diaz wrote:
>> 
>> >
>> >
>> >> On Jan 18, 2005, at 1:17 AM, Miguel Angel Diaz wrote:
>> >>
>> >>> How to find out your ISP domain name? It is simple, just type:
>> >>>
>> >>> dig soa -x 195.64.92.136 +noall +authority
>> >>>
>> >>> and extract the domain from the authoritative DNS server
>> >>> (ns.cistron.nl)  :-)
>> >>
>> >> Can you tell us how this will work for host behind a NAT which address
>> >> is 192.168.1.2?
>> >>
>> >
>> > of course, you first has to know your public IPv4 address ;-) It 
>> > doesn't matter if you have one or more NAT levels, the only thing is 
>> > to find out your final public address. There are several ways to do it 
>> > and one of the most used is the STUN protocol, RFC 3489.
>> 
>> I was expecting this answer. Can you now tell how to discover which 
>> stun server to use?
> 
> That is why I offered him the traceroute option, to at least get the
> IP's and then the reverses of the ISP, not that it would be really
> visible and quite hard to find out then where a) to trace to and b)
> which hop actually belongs to the ISP, but still ;)
> 

With traceroute it would be even better to discover the IP, at least and some scnerios

> Also miguel, you really think that I did not have a special reverse on
> my box? At least internally 195.64.92.136 is also nicely known as
> purgatory.unfix.org and thus the SOA is also inside unfix.org, the NS
> records are at purgatory.unfix.org and ns1/ns2.mediadesign.nl. Does this
> lead you to cistron.nl?

So that's one case where tracertoue might be more usefull because it would be used the IP of your ISP default gateway rather than your ouwn public IP

> 
> I also have to note that:
> - many ISP's don't do reverse at all

The most of IP tests we've made shown the oposite. I guess that the most of ISP do it. Anyway, with discovery based on DNS, ISP will be adviced that reverse is a must.

> - the ISP's that usually do not use the same domain name as they
>   use for their services.

Again, ISP will be adviced that the domain used for discovering should be the same that the one usen on reverse

> - custom reverses exist too.

So, trying reverse with the first hop of the customer's network, that is the ISP gateway
will solve it.

Regards
Miguel

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