13cef2ee09
* plugin/dnssec: use entire RRset as key input This uses the entire rrset as input for the hash key; this is to detect differences in the RRset and generate the correct signature. As this would then lead to unbounded growth, we periodically (every 8h) prune the cache of old entries. In theory we could rely on the random eviction, but it seems nicer to do this in a maintannce loop so that we remove the unused ones. This required adding a Walk function to the plugin/pkg/cache. Signed-off-by: Miek Gieben <miek@miek.nl> * Update plugin/dnssec/cache.go Co-authored-by: Chris O'Haver <cohaver@infoblox.com> Co-authored-by: Chris O'Haver <cohaver@infoblox.com>
87 lines
3 KiB
Markdown
87 lines
3 KiB
Markdown
# dnssec
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## Name
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*dnssec* - enables on-the-fly DNSSEC signing of served data.
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## Description
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With *dnssec*, any reply that doesn't (or can't) do DNSSEC will get signed on the fly. Authenticated
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denial of existence is implemented with NSEC black lies. Using ECDSA as an algorithm is preferred as
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this leads to smaller signatures (compared to RSA). NSEC3 is *not* supported.
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This plugin can only be used once per Server Block.
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## Syntax
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~~~
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dnssec [ZONES... ] {
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key file KEY...
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cache_capacity CAPACITY
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}
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~~~
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The signing behavior depends on the keys specified. If multiple keys are specified of which there is
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at least one key with the SEP bit set and at least one key with the SEP bit unset, signing will happen
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in split ZSK/KSK mode. DNSKEY records will be signed with all keys that have the SEP bit set. All other
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records will be signed with all keys that do not have the SEP bit set.
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In any other case, each specified key will be treated as a CSK (common signing key), forgoing the
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ZSK/KSK split. All signing operations are done online.
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Authenticated denial of existence is implemented with NSEC black lies. Using ECDSA as an algorithm
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is preferred as this leads to smaller signatures (compared to RSA). NSEC3 is *not* supported.
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As the *dnssec* plugin can't see the original TTL of the RRSets it signs, it will always use 3600s
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as the value.
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If multiple *dnssec* plugins are specified in the same zone, the last one specified will be
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used.
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* **ZONES** zones that should be signed. If empty, the zones from the configuration block
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are used.
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* `key file` indicates that **KEY** file(s) should be read from disk. When multiple keys are specified, RRsets
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will be signed with all keys. Generating a key can be done with `dnssec-keygen`: `dnssec-keygen -a
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ECDSAP256SHA256 <zonename>`. A key created for zone *A* can be safely used for zone *B*. The name of the
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key file can be specified in one of the following formats
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* basename of the generated key `Kexample.org+013+45330`
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* generated public key `Kexample.org+013+45330.key`
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* generated private key `Kexample.org+013+45330.private`
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* `cache_capacity` indicates the capacity of the cache. The dnssec plugin uses a cache to store
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RRSIGs. The default for **CAPACITY** is 10000.
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## Metrics
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If monitoring is enabled (via the *prometheus* plugin) then the following metrics are exported:
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* `coredns_dnssec_cache_entries{server, type}` - total elements in the cache, type is "signature".
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* `coredns_dnssec_cache_hits_total{server}` - Counter of cache hits.
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* `coredns_dnssec_cache_misses_total{server}` - Counter of cache misses.
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The label `server` indicated the server handling the request, see the *metrics* plugin for details.
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## Examples
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Sign responses for `example.org` with the key "Kexample.org.+013+45330.key".
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~~~ corefile
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example.org {
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dnssec {
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key file Kexample.org.+013+45330
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}
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whoami
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}
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~~~
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Sign responses for a kubernetes zone with the key "Kcluster.local+013+45129.key".
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~~~
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cluster.local {
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kubernetes
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dnssec {
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key file Kcluster.local+013+45129
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}
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}
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~~~
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