3e196a6d57
* middleware/reverse: random updates Make the documentation somewhat shorter (and hopefully clearer in the process). Also to be on-par with the *auto* middleware, start counting the referenced zones from 1 (instead of 0). Some variable cleanups and use the NextOrFailure in the ServeDNS function. * More TODOs
84 lines
2.6 KiB
Markdown
84 lines
2.6 KiB
Markdown
# reverse
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The *reverse* middleware allows CoreDNS to respond dynamicly to an PTR request and the related A/AAAA request.
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## Syntax
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~~~
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reverse NETWORK... {
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hostname TEMPLATE
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[ttl TTL]
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[fallthrough]
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~~~
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* **NETWORK** one or more CIDR formatted networks to respond on.
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* `hostname` inject the IP and zone to an template for the hostname. Defaults to "ip-{IP}.{zone[1]}". See below for template.
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* `ttl` defaults to 60
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* `fallthrough` If zone matches and no record can be generated, pass request to the next middleware.
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### Template Syntax
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The template for the hostname is used for generating the PTR for an reverse lookup and matching the
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forward lookup back to an IP.
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#### `{ip}`
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The `{ip}` symbol is **required** to make reverse work.
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For IPv4 lookups the "." is replaced with an "-", i.e.: 10.1.1.1 results in "10-1-1-1"
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With IPv6 lookups the ":" is removed, and any zero ranged are expanded, i.e.:
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"ffff::ffff" results in "ffff000000000000000000000000ffff"
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#### `{zone[i]}`
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The `{zone[i]}` symbol is **optional** and can be replaced by a fixed (zone) string.
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The zone will be matched by the zones listed in *this* configuration stanza.
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`i` needs to be replaced to the index of the configured listener zones, starting with 1.
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## Examples
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~~~ txt
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arpa compute.internal {
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# proxy unmatched requests
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proxy . 8.8.8.8
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# answer requests for IPs in this networks
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# PTR 1.0.32.10.in-addr.arpa. 3600 ip-10-0-32-1.compute.internal.
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# A ip-10-0-32-1.compute.internal. 3600 10.0.32.1
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# v6 is also possible
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# PTR 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.d.f.ip6.arpa. 3600 ip-fd010000000000000000000000000001.compute.internal.
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# AAAA ip-fd010000000000000000000000000001.compute.internal. 3600 fd01::1
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reverse 10.32.0.0/16 fd01::/16 {
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# template of the ip injection to hostname, zone resolved to compute.internal.
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hostname ip-{ip}.{zone[2]}
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ttl 3600
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# Forward unanswered or unmatched requests to proxy # without this flag, requesting A/AAAA
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records on compute.internal. will end here.
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fallthrough
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}
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}
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~~~
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~~~ txt
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32.10.in-addr.arpa.arpa arpa.company.org {
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reverse 10.32.0.0/16 {
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# template of the ip injection to hostname, zone resolved to arpa.company.org.
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hostname "ip-{ip}.v4.{zone[2]}"
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ttl 3600
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# fallthrough is not required, v4.arpa.company.org. will be only answered here
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}
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# cidr closer to the ip wins, so we can overwrite the "default"
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reverse 10.32.2.0/24 {
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# its also possible to set fix domain suffix
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hostname ip-{ip}.fix.arpa.company.org.
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ttl 3600
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}
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}
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~~~
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