dnssec

README

dnssec

dnssec enables on-the-fly DNSSEC signing of served data.

Syntax

dnssec [ZONES...]

• ZONES zones that should be signed. If empty, the zones from the configuration block are used.

If keys are not specified (see below), a key is generated and used for all signing operations. The DNSSEC signing will treat this key a CSK (common signing key), forgoing the ZSK/KSK split. All signing operations are done online. Authenticated denial of existence is implemented with NSEC black lies. Using ECDSA as an algorithm is preferred as this leads to smaller signatures (compared to RSA). NSEC3 is not supported.

A single signing key can be specified by using the key directive.

NOTE: Key generation has not been implemented yet.

TODO(miek): think about key rollovers, and how to do them automatically.

dnssec [ZONES... ] {
    key file KEY...
    cache_capacity CAPACITY
}

• key file indicates that key file(s) should be read from disk. When multiple keys are specified, RRsets will be signed with all keys. Generating a key can be done with dnssec-keygen: dnssec-keygen -a ECDSAP256SHA256 <zonename>. A key created for zone A can be safely used for zone B.

• cache_capacity indicates the capacity of the LRU cache. The dnssec middleware uses LRU cache to manage objects and the default capacity is 10000.

Metrics

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

• coredns_dnssec_cache_size{type} - total elements in the cache, type is "signature".
• coredns_dnssec_cache_capacity{type} - total capacity of the cache, type is "signature".
• coredns_dnssec_cache_hits_total - Counter of cache hits.
• coredns_dnssec_cache_misses_total - Counter of cache misses.

Examples

Documentation

Overview

Package dnssec implements a middleware that signs responses on-the-fly using NSEC black lies.

Index

• type DNSKEY
  • func ParseKeyFile(pubFile, privFile string) (*DNSKEY, error)
• type Dnssec
  • func New(zones []string, keys []*DNSKEY, next middleware.Handler, cache *lru.Cache) Dnssec
  • func (d Dnssec) Name() string
  • func (d Dnssec) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)
  • func (d Dnssec) Sign(state request.Request, zone string, now time.Time) *dns.Msg
• type ResponseWriter
  • func (d *ResponseWriter) Hijack()
  • func (d *ResponseWriter) Write(buf []byte) (int, error)
  • func (d *ResponseWriter) WriteMsg(res *dns.Msg) error

Types

type DNSKEY

type DNSKEY struct {
	K *dns.DNSKEY
	// contains filtered or unexported fields
}

DNSKEY holds a DNSSEC public and private key used for on-the-fly signing.

func ParseKeyFile

func ParseKeyFile(pubFile, privFile string) (*DNSKEY, error)

ParseKeyFile read a DNSSEC keyfile as generated by dnssec-keygen or other utilities. It adds ".key" for the public key and ".private" for the private key.

type Dnssec

type Dnssec struct {
	Next middleware.Handler
	// contains filtered or unexported fields
}

Dnssec signs the reply on-the-fly.

func New

func New(zones []string, keys []*DNSKEY, next middleware.Handler, cache *lru.Cache) Dnssec

New returns a new Dnssec.

func (Dnssec) Name

func (d Dnssec) Name() string

Name implements the Handler interface.

func (Dnssec) ServeDNS

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

ServeDNS implements the middleware.Handler interface.

func (Dnssec) Sign

func (d Dnssec) Sign(state request.Request, zone string, now time.Time) *dns.Msg

Sign signs the message in state. it takes care of negative or nodata responses. It uses NSEC black lies for authenticated denial of existence. Signatures creates will be cached for a short while. By default we sign for 8 days, starting 3 hours ago.

type ResponseWriter

type ResponseWriter struct {
	dns.ResponseWriter
	// contains filtered or unexported fields
}

ResponseWriter sign the response on the fly.

func (*ResponseWriter) Hijack

func (d *ResponseWriter) Hijack()

Hijack implements the dns.ResponseWriter interface.

func (*ResponseWriter) Write

func (d *ResponseWriter) Write(buf []byte) (int, error)

Write implements the dns.ResponseWriter interface.

func (*ResponseWriter) WriteMsg

func (d *ResponseWriter) WriteMsg(res *dns.Msg) error

WriteMsg implements the dns.ResponseWriter interface.