== NTK_RFC 0004 ==

Subject: Mail Exchange request

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This text describes how the MX DNS query are resolved by ANDNA.

		    * WARNING *
This RFC has been deprecated by the NTK_RFC 0009
		    * WARNING *
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In the DNS the resolution of the MX field is handled directly by the DNS
servers, in ANDNA, instead, the resolution of an MX hostname is a redirect
request. In short it means that the request, instead of being sent to a
hash_node, is sent to the register_node itself,

== hname MX resolution ==

The resolution of a MX hostnames in ANDNA works in this way:
 * We are trying to resolve the MX of the "pippo" hname.
 * "pippo" is resolved normally and the IP of the register_node is gained.
 * We ask to the register_node the IP of its MX.

== hname MX registration ==

Since the IP of the MX node can change during the time, the register_node must
be aware of its current IP.
It is the MX node itself that tells the register_node its current IP each time
it changes. The MX node to contact the register_node has to simply resolve its
hname.
The register_node has to verify the authenticity of the IP update request,
therefore the MX node will sign the request with the private key of the
register_node.

This system is necessary because the MX node and the register node have to be
synced. In this way when the register_node dies or can't be reached anymore,
the MX node can't be contacted too.
Moreover this system prevents the spoofing of the MX node.

The steps necessary to register a hname MX are:
 * Copy the ANDNA private key of the register node, which is saved in its lcl_cache, to the MX node:
{{{
register_node# scp /usr/share/netsukuku/andna_lcl_keyring mx_node:/etc/netsukuku/mx/<HNAME_MX>
# <HNAME_MX> is the hname relative to the MX node
}}}
 * Send a SIGHUP to the MX NetsukukuD:
{{{
register_node# ssh mx_node "killall -SIGHUP ntkd"
}}}


If no MX is associated to an hostname, the register_node will use its own IP
as the default MX IP.
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related: [Netsukuku_RFC]