64 lines
2.2 KiB
Markdown
64 lines
2.2 KiB
Markdown
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## ADDRESS03: Reverse DNS entry matches name server name
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### Test case identifier
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**ADDRESS03** Reverse DNS entry matches name server name
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### Objective
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Some anti-spam techniques use reverse DNS lookup to allow incoming traffic.
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In order to prevent name servers to be blocked or blacklisted, DNS
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administrators should publish PTR records associated with the name server
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addresses.
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Moreover, as mentioned in paragraph 2.1 of [RFC
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1912](https://datatracker.ietf.org/doc/html/rfc1912) when a PTR record exists, it must match the host
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name.
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### Inputs
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The domain name to be tested.
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### Ordered description of steps to be taken to execute the test case
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1. Obtain the IP addresses of each name server of the domain from the child
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using [Method5](../Methods.md).
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These IP addresses can be associated to the name servers through a hash
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table where each address is a key and the name server it's unique value.
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Let's call this hash table HASH1.
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2. Obtain the reverse DNS entries associated to name servers names as described
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in test case [ADDRESS02](address02.md). Let's call its outcome HASH2 which
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consists of IP addresses as keys and hostnames as values. As multiple PTR
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records are allowed, an IP address can have several corresponding hostnames.
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3. Compare HASH2 to HASH1.
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Parse the address list of HASH1.
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For an address (a) of HASH1, take the corresponding hostname (h) in HASH1.
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If this hostname (h) is present in the hostnames list associated to this
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address (a) in HASH2, then the test succeeds for address (a).
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If the hostname (h) does not match any hostnames associated to address (a)
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in HASH2, then the test fails for address (a).
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If the test fails for one IP address, the whole test case fails.
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### Outcome(s)
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Multiple addresses and multiple PTR records are allowed. The test
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succeeds if every name server address has one or more PTR records
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and one of these records matches the server name.
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If one address doesn't match, the whole test case fails.
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### Special procedural requirements
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None.
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### Intercase dependencies
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Some of the input of this test comes as the result of test case
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[ADDRESS02](address02.md). [ADDRESS02](address02.md) must succeed
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prior to proceed with this test case [ADDRESS03](address03.md).
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