Introduction
DNSSEC, which stands for Domain Name System Security Extensions, is a suite of specifications designed to enhance the security and integrity of the Domain Name System (DNS). Introduced to address vulnerabilities in the original DNS protocol, DNSSEC adds a layer of trust to DNS responses, helping to protect against various forms of DNS-based attacks.
Key Features and Characteristics
DNSSEC introduces several crucial features to improve DNS security:
- Origin Authentication: Ensures that DNS responses come from the authoritative source.
- Data Integrity: Verifies that the data hasn't been tampered with during transmission.
- Authenticated Denial of Existence: Proves that a requested DNS record does not exist.
DNSSEC achieves these features through the use of:
- Digital Signatures: Each DNS record is cryptographically signed.
- Public Key Cryptography: Utilizes a pair of public and private keys for signing and verification.
- Chain of Trust: Establishes a hierarchical authentication from the root zone down to individual domain names.
How DNSSEC Works
- Zone Signing: The domain owner generates a pair of keys (ZSK - Zone Signing Key and KSK - Key Signing Key) and signs all records in their DNS zone.
- Key Publication: The public part of these keys is published in the DNS as DNSKEY records.
- Signature Creation: For each RRset (Resource Record Set), an RRSIG (Resource Record Signature) is created.
- Validation: When a DNSSEC-aware resolver receives a response, it checks the RRSIG against the DNSKEY to verify the authenticity and integrity of the data.
Example of a signed DNS record:
example.com. IN A 192.0.2.1
example.com. IN RRSIG A 5 2 3600 20230515235959 20230415235959 12345 example.com. <signature>
Limitations and Challenges