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86 lines
3.6 KiB
Markdown
86 lines
3.6 KiB
Markdown
---
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name: PTR
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parameters:
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- name
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- target
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- modifiers...
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---
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PTR adds a PTR record to the domain.
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The name is normally a the relative label for the domain, or a FQDN that ends with `.`. If magic mode is enabled (see below) it can also be an IP address, which will be replaced by the proper string automatically, thus
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saving the user from having to reverse the IP address manually.
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Target should be a string representing the FQDN of a host. Like all FQDNs in DNSControl, it must end with a `.`.
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**Magic Mode:**
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PTR records are complex and typos are common. Therefore DNSControl
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enables features to save labor and
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prevent typos. This magic is only
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enabled when the domain ends with `in-addr.arpa.` or `ipv6.arpa.`.
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*Automatic IP-to-reverse:* If the name is a valid IP address, DNSControl will replace it with
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a string that is appropriate for the domain. That is, if the domain
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ends with `in-addr.arpa` (no `.`) and name is a valid IPv4 address, the name
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will be replaced with the correct string to make a reverse lookup for that address.
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IPv6 is properly handled too.
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*Extra Validation:* DNSControl considers it an error to include a name that
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is inappropriate for the domain. For example
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`PTR('1.2.3.4', 'f.co.')` is valid for the domain `D("3.2.1.in-addr.arpa',`
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but DNSControl will generate an error if the domain is `D("9.9.9.in-addr.arpa',`.
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This is because `1.2.3.4` is contained in `1.2.3.0/24` but not `9.9.9.0/24`.
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This validation works for IPv6, IPv4, and
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RFC2317 "Classless in-addr.arpa delegation" domains.
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*Automatic truncation:* DNSControl will automatically truncate FQDNs
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as needed.
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If the name is a FQDN ending with `.`, DNSControl will verify that the
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name is contained within the CIDR block implied by domain. For example
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if name is `4.3.2.1.in-addr.arpa.` (note the trailing `.`)
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and the domain is `2.1.in-addr.arpa` (no trailing `.`)
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then the name will be replaced with `4.3`. Note that the output
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of `REV('1.2.3.4')` is `4.3.2.1.in-addr.arpa.`, which means the following
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are all equivalent:
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* `PTR(REV('1.2.3.4'), `
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* `PTR('4.3.2.1.in-addr.arpa.'), `
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* `PTR('4.3',` // Assuming the domain is `2.1.in-addr.arpa`
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All magic is RFC2317-aware. We use the first format listed in the
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RFC for both `REV()` and `PTR()`. The format is
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`FIRST/MASK.C.B.A.in-addr.arpa` where `FIRST` is the first IP address
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of the zone, `MASK` is the netmask of the zone (25-31 inclusive),
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and A, B, C are the first 3 octets of the IP address. For example
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`172.20.18.130/27` is located in a zone named
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`128/27.18.20.172.in-addr.arpa`
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{% include startExample.html %}
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```js
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D(REV('1.2.3.0/24'), REGISTRAR, DnsProvider(BIND),
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PTR('1', 'foo.example.com.'),
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PTR('2', 'bar.example.com.'),
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PTR('3', 'baz.example.com.'),
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// If the first parameter is a valid IP address, DNSControl will generate the correct name:
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PTR('1.2.3.10', 'ten.example.com.'), // '10'
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);
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D(REV('9.9.9.128/25'), REGISTRAR, DnsProvider(BIND),
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PTR('9.9.9.129', 'first.example.com.'),
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);
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D(REV('2001:db8:302::/48'), REGISTRAR, DnsProvider(BIND),
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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', 'foo.example.com.'), // 2001:db8:302::1
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// If the first parameter is a valid IP address, DNSControl will generate the correct name:
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PTR('2001:db8:302::2', 'two.example.com.'), // '2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0'
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PTR('2001:db8:302::3', 'three.example.com.'), // '3.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0'
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);
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```
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{% include endExample.html %}
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In the future we plan on adding a flag to `A()` which will insert
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the correct PTR() record if the appropriate `.arpa` domain has been
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defined.
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