dns64

README

dns64

Name

dns64 - enables DNS64 IPv6 transition mechanism.

Description

The dns64 plugin will when asked for a domain's AAAA records, but only finds A records, synthesizes the AAAA records from the A records.

The synthesis is only performed if the query came in via IPv6.

This translation is for IPv6-only networks that have NAT64.

Syntax

dns64 [PREFIX]

• PREFIX defines a custom prefix instead of the default 64:ff9b::/96.

Or use this slightly longer form with more options:

dns64 [PREFIX] {
    [translate_all]
    prefix PREFIX
}

• prefix specifies any local IPv6 prefix to use, instead of the well known prefix (64:ff9b::/96)
• translate_all translates all queries, including responses that have AAAA results.

Examples

Translate with the default well known prefix. Applies to all queries (if they came in over IPv6).

. {
    dns64
}

Use a custom prefix.

. {
    dns64 64:1337::/96
}

Or

. {
    dns64 {
        prefix 64:1337::/96
    }
}

Enable translation even if an existing AAAA record is present.

. {
    dns64 {
        translate_all
    }
}

Metrics

If monitoring is enabled (via the prometheus plugin) then the following metrics are exported:

• coredns_dns64_requests_translated_total{server} - counter of DNS requests translated

The server label is explained in the prometheus plugin documentation.

Bugs

Not all features required by DNS64 are implemented, only basic AAAA synthesis.

• Support "mapping of separate IPv4 ranges to separate IPv6 prefixes"
• Resolve PTR records
• Make resolver DNSSEC aware. See: RFC 6147 Section 3

See Also

See RFC 6147 for more information on the DNS64 mechanism.

Documentation

Overview

Package dns64 implements a plugin that performs DNS64.

See: RFC 6147 (https://tools.ietf.org/html/rfc6147)

Index

• Variables
• type DNS64
  • func (d *DNS64) DoDNS64(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, origResponse *dns.Msg) (*dns.Msg, error)
  • func (d *DNS64) Name() string
  • func (d *DNS64) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)
  • func (d *DNS64) Synthesize(origReq, origResponse, resp *dns.Msg) *dns.Msg
• type UpstreamInt

Variables

var (
	// RequestsTranslatedCount is the number of DNS requests translated by dns64.
	RequestsTranslatedCount = promauto.NewCounterVec(prometheus.CounterOpts{
		Namespace: plugin.Namespace,
		Subsystem: pluginName,
		Name:      "requests_translated_total",
		Help:      "Counter of DNS requests translated by dns64.",
	}, []string{"server"})
)

Types

type DNS64

type DNS64 struct {
	Next         plugin.Handler
	Prefix       *net.IPNet
	TranslateAll bool // Not comply with 5.1.1
	Upstream     UpstreamInt
}

DNS64 performs DNS64.

func (*DNS64) DoDNS64

func (d *DNS64) DoDNS64(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, origResponse *dns.Msg) (*dns.Msg, error)

DoDNS64 takes an (empty) response to an AAAA question, issues the A request, and synthesizes the answer. Returns the response message, or error on internal failure.

func (*DNS64) Name

func (d *DNS64) Name() string

Name implements the Handler interface.

func (*DNS64) ServeDNS

func (d *DNS64) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)

ServeDNS implements the plugin.Handler interface.

func (*DNS64) Synthesize

func (d *DNS64) Synthesize(origReq, origResponse, resp *dns.Msg) *dns.Msg

Synthesize merges the AAAA response and the records from the A response

type UpstreamInt

type UpstreamInt interface {
	Lookup(ctx context.Context, state request.Request, name string, typ uint16) (*dns.Msg, error)
}

UpstreamInt wraps the Upstream API for dependency injection during testing