DNSSEC (Domain Name System Security Extensions) is a set of extensions to the DNS protocol that provides secure, authenticated domain name resolution. DNSSEC is designed to prevent DNS spoofing attacks and provide end-to-end authenticity and integrity for DNS data.
Functions of DNSSEC:
- Authenticity: DNSSEC allows the client to verify that the DNS response has not been tampered with or altered in any way.
- Integrity: DNSSEC ensures that the data in the DNS response is the same as the data originally published by the domain owner.
- Non-repudiation: DNSSEC provides a means of proving that a domain name owner actually authorized the publication of the DNS data.
- Confidentiality: DNSSEC does not provide confidentiality; it only ensures the authenticity and integrity of DNS data.
Components of DNSSEC:
- Zone signing: A domain owner signs the zone file with a private key to create a digital signature. This signature is then distributed to DNS resolvers.
- Key signing: DNSSEC uses public-key cryptography to establish trust between DNS resolvers and domain name owners. This involves the use of a public key for DNS resolvers to verify the digital signature created by the domain owner.
- Chain of trust: DNSSEC creates a chain of trust between the root DNS zone, TLD (Top-Level Domain) zone, and the domain name owner’s zone. Each zone signs the zone file with its private key, and the public key is distributed to the next zone in the chain.
How to configure DNSSEC:
- Generate key pairs: The domain owner generates a private-public key pair using a key generation tool.
- Sign the zone file: The domain owner signs the zone file with the private key and generates a digital signature.
- Publish the DNSSEC records: The domain owner publishes the public key, digital signature, and DNSSEC records in the zone file.
- Update the registrar: The domain owner updates the registrar with the DNSSEC information.
- Configure DNSSEC on the DNS resolver: The DNS resolver is configured with the public key to verify the digital signature and authenticate the DNS response.
Query flow:
- The DNS resolver receives a query for a domain name from a client.
- The DNS resolver checks the DNSSEC records for the domain name to see if they have been signed.
- If the DNSSEC records are signed, the DNS resolver retrieves the public key for the domain name and verifies the digital signature.
- If the digital signature is verified, the DNS resolver returns the DNS response to the client.
- If the digital signature is not verified, the DNS resolver does not return the DNS response and may log the event as a potential DNS spoofing attack.
