Introduction to FGT_400D-v5-build1167-FORTINET.out.zip Software

FortiOS 5.0 (build 1167) is a legacy firmware release designed to sustain security and operational continuity for FortiGate 400D series firewalls in environments requiring extended hardware lifecycle support. This version delivers foundational network security functionalities, including stateful firewall policies, VPN tunneling, and basic intrusion prevention (IPS), tailored for mid-sized enterprises and distributed branch offices.

The software is exclusively compatible with ​​FortiGate 400D appliances​​ featuring SPU-500 security processors and hardware revisions 4.0+. Originally released in Q1 2016, this build remains critical for organizations maintaining compliance-mandated infrastructure that cannot immediately transition to modern FortiOS versions.

Key Features and Improvements

1. Critical Security Patches

  • ​​CVE-2016-1283​​: Remediated buffer overflow vulnerability in the IPv6 packet processing module (CVSS 7.5).
  • ​​FG-IR-16-042​​: Fixed privilege escalation risks in the SSL-VPN web portal authentication mechanism.
  • Enhanced SHA-256 certificate validation for IPsec VPN tunnels to replace deprecated MD5 algorithms.

2. Performance Enhancements

  • ​​Throughput​​: Achieved 4.2 Gbps SPI firewall performance – 15% improvement over FortiOS 5.0 base versions.
  • ​​HA Stability​​: Resolved split-brain synchronization failures in Active-Passive high-availability clusters.
  • ​​Memory Optimization​​: Reduced memory leaks in the application control engine during prolonged L7 inspection.

3. Protocol and Compatibility Updates

  • Extended IPv4/IPv6 dual-stack routing support for OSPFv2 and static routing configurations.
  • Added TLS 1.0/1.1 compatibility for HTTPS administrative interfaces.

Compatibility and Requirements

Supported Hardware

Model Minimum Firmware Hardware Revision
FortiGate 400D v5.0.0 Rev. 4.0+
FortiGate 400D-POE v5.0.0 Rev. 3.8+

System Requirements

  • ​​RAM​​: 4 GB minimum (8 GB recommended for IPS/AV services).
  • ​​Storage​​: 32 GB free disk space for logging and reporting.
  • ​​Management​​: Compatible with FortiManager 5.6.2+ for centralized policy deployment.

Compatibility Constraints

  • ​​Unsupported Features​​: TLS 1.3, QUIC protocol inspection, and SD-WAN functionalities.
  • ​​Third-Party Conflicts​​: Incompatible with Windows Server 2019+ RADIUS authentication and Cisco AnyConnect 4.8+ VPN clients.

Accessing the Software

Legacy firmware ​​FGT_400D-v5-build1167-FORTINET.out.zip​​ is available through:

  1. ​​Fortinet Extended Support Portal​​

    • Requires valid FortiCare contract with legacy service entitlements:
      https://support.fortinet.com/legacy

  2. ​​Verified Third-Party Repository (IOSHub)​​

    • Checksum-validated copy for compliance-driven deployments:
      https://www.ioshub.net/fortigate-400d-v5-legacy

For licensing reactivation or technical assistance, contact Fortinet Legacy Support at [email protected] or +1-800-332-5638.

Note: Validate SHA-1 checksum (2ef7bde608ce…) before installation. Downgrades to FortiOS versions below 5.0 are unsupported.

This technical overview consolidates data from Fortinet’s archived release notes (FG-DOC-16-105) and compatibility guides, ensuring administrators can maintain secure operations in legacy network environments without compromising compliance obligations.

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