RFC 5425 — TLS Transport for Syslog

Q: What does the Introduction section cover in RFC 5425 — TLS Transport for Syslog?

The Introduction section provides detailed technical specifications, security considerations, and implementation guidance as documented in RFC 5425 — TLS Transport for Syslog. This content is part of the BLACKLABS RFC Reference Library.

Q: What does the Transport Architecture section cover in RFC 5425 — TLS Transport for Syslog?

The Transport Architecture section provides detailed technical specifications, security considerations, and implementation guidance as documented in RFC 5425 — TLS Transport for Syslog. This content is part of the BLACKLABS RFC Reference Library.

Q: What does the TLS Requirements section cover in RFC 5425 — TLS Transport for Syslog?

The TLS Requirements section provides detailed technical specifications, security considerations, and implementation guidance as documented in RFC 5425 — TLS Transport for Syslog. This content is part of the BLACKLABS RFC Reference Library.

Q: What does the Message Framing section cover in RFC 5425 — TLS Transport for Syslog?

The Message Framing section provides detailed technical specifications, security considerations, and implementation guidance as documented in RFC 5425 — TLS Transport for Syslog. This content is part of the BLACKLABS RFC Reference Library.

Q: What does the Security Considerations section cover in RFC 5425 — TLS Transport for Syslog?

The Security Considerations section provides detailed technical specifications, security considerations, and implementation guidance as documented in RFC 5425 — TLS Transport for Syslog. This content is part of the BLACKLABS RFC Reference Library.

BLACKLABS

RFC 5425 — TLS Transport for Syslog

Transport Layer Security (TLS) Transport Mapping for Syslog — secure, reliable delivery of syslog messages over TLS, providing encryption, authentication, and integrity for audit log transport.

Standards Track March 2009 ISO 27001

1. Introduction

▶

RFC 5425 defines the use of TLS to provide a secure, connection-oriented transport for syslog messages. This addresses the critical ISO 27001 requirement that security logs must be protected against tampering and unauthorized access during transport.

ISO 27001 Relevance: A.8.15 (Logging) — secure transport ensures log integrity. A.8.24 (Use of Cryptography) — TLS provides encryption and authentication for log data in transit.

2. Transport Architecture

▶

  Syslog Sender          TLS Channel (port 6514)          Syslog Collector
  ┌──────────┐         ┌─────────────────────┐         ┌──────────────┐
  │ App Logs │──MSG──>│ TLS 1.2+            │──MSG──>│ SIEM/Log     │
  │ Auth Logs│        │ Mutual Auth (opt)   │        │ Aggregator   │
  │ Sys Logs │        │ AES-256-GCM         │        │ Analysis     │
  └──────────┘        └─────────────────────┘         └──────────────┘

3. TLS Requirements

▶

TLS version: MUST support TLS 1.2+ (SHOULD use TLS 1.3 per RFC 9325)
Server authentication: Syslog collector MUST present a valid certificate
Client authentication: Mutual TLS RECOMMENDED for sender identity verification
Certificate validation: Full chain validation per RFC 5280
Session resumption: Supported for performance with persistent connections

4. Message Framing

▶

TLS transport uses octet-counting framing to delineate syslog messages within the TLS stream:

  MSG-LEN SP SYSLOG-MSG MSG-LEN SP SYSLOG-MSG ...

  Example:
  195 <34>1 2026-03-29T17:30:00Z host app 1234 AUTH [...] msg

This avoids the delimiter-based framing issues of traditional UDP syslog.

5. Security Considerations

▶

Certificate management: Automate certificate rotation per A.8.24 — consider ACME (RFC 8555)
Connection persistence: Maintain persistent TLS connections to avoid handshake overhead and log gaps
Failover: Configure secondary collectors for high availability of audit logs
Cipher suites: Use AEAD cipher suites (AES-GCM) — disable CBC mode