TLSA Records Explained

What is a TLSA Record?

A TLSA (Transport Layer Security Authentication) record is used for DANE (DNS-based Authentication of Named Entities) protocol. It allows you to specify which TLS certificate or public key should be used for a service, providing an additional layer of security beyond traditional certificate authorities.

Format:

_port._proto.domain.com. IN TLSA ( usage selector matching-type certificate-data )

Examples:

# HTTPS server certificate
_443._tcp.example.com. IN TLSA 3 1 1 123456789abcdef...

# SMTP with STARTTLS
_25._tcp.mail.example.com. IN TLSA 2 0 1 abcdef123456...

# Secure IMAP
_993._tcp.imap.example.com. IN TLSA 1 1 2 fedcba987654...

Parameters Explained

•
Usage (Certificate Usage)
0: CA constraint 1: Service certificate constraint 2: Trust anchor assertion 3: Domain-issued certificate
•
Selector
0: Full certificate 1: SubjectPublicKeyInfo
•
Matching Type
0: Exact match 1: SHA-256 hash 2: SHA-512 hash
•
Certificate Association Data
The actual certificate or public key data, formatted according to the selector and matching type

Common Uses

Securing HTTPS connections beyond CA validation
Protecting email services (SMTP, IMAP, POP3)
Securing SIP and XMPP communications
Certificate pinning at DNS level
Protecting against fraudulent certificates

Best Practices

✓
Use appropriate usage modes
Choose the right certificate usage mode based on your security requirements and infrastructure.
✓
Implement DNSSEC
Always use DNSSEC with TLSA records to ensure the integrity of the certificate data.
✓
Regular updates
Keep TLSA records in sync with certificate renewals and changes.

Common Pitfalls

⚠️
Certificate mismatch
TLSA records not updated when certificates are renewed can cause service disruption.
⚠️
Missing DNSSEC
TLSA records without DNSSEC protection are vulnerable to tampering.
⚠️
Incorrect port/protocol
Using wrong port or protocol in TLSA record names can prevent proper validation.

Advanced Tips

Certificate Rollover

Implement proper certificate rollover procedures by publishing new TLSA records before deploying new certificates and maintaining both records during transition.

Multiple Records

Consider publishing multiple TLSA records with different matching types or selectors to provide fallback options and improve reliability.

Automation

Implement automated systems to update TLSA records when certificates are renewed to prevent mismatches and service disruptions.

Security Considerations

🔒
DNSSEC Requirements
Ensure DNSSEC is properly configured and maintained to protect TLSA records.
🔒
Key Management
Implement secure key management practices for both certificates and DNSSEC keys.
🔒
Monitoring
Regularly monitor TLSA record validity and certificate expiration dates.

Beep beep... Loading...