EE Single Server Conversion Tool for Forefront TMG: Features & Compatibility Notes

Migrating Forefront TMG: EE Single Server Conversion Tool Best PracticesForefront Threat Management Gateway (TMG) reached end of life years ago, but many organizations still rely on it for perimeter security, VPN access, and web proxying. Migrating away from TMG is often necessary for security, compliance, and supportability. The EE Single Server Conversion Tool (EE SSCT) can simplify migrations by converting a TMG single-server deployment to a supported edge or perimeter platform. This article outlines best practices, planning steps, operational guidance, and troubleshooting tips to help IT teams perform a smooth migration with minimal downtime and configuration drift.

Overview: What the EE Single Server Conversion Tool does

The EE Single Server Conversion Tool analyzes configurations on a Forefront TMG single-server deployment and exports policies, NAT rules, network definitions, VPN settings, certificate references, and other relevant artifacts into a format consumable by the target EE platform. It’s not a symmetric, perfect one-to-one converter — TMG-specific features or legacy behaviors may require manual adjustments after conversion. Treat the tool as an accelerator for migration, not a full replacement for planning and validation.

Pre-migration planning

Careful planning reduces risk. Follow these preparatory steps:

• Inventory and document current TMG environment:

  • List network interfaces, IP addresses, subnets, and routing.
  • Export TMG configuration and policy XML for reference.
  • Record VPN types, authentication methods, and user groups.
  • Catalog SSL certificates and private keys used for HTTPS inspection, client access, and VPN.

• Identify feature gaps:

  • Map TMG features in use (URL filtering, HTTP inspection, application-layer rules, web caching) to capabilities in the EE target platform.
  • Note features that require manual re-implementation or third-party products.

• Establish rollback and backup plans:

  • Ensure full backups of TMG server and key network devices.
  • Prepare a rollback plan for DNS changes and routing adjustments.
  • Plan maintenance windows and a communication plan for stakeholders.

• Lab and testing environment:

  • Build a staging environment that mirrors production where possible.
  • Use copies of configurations and test data to validate the EE platform with converted settings.

• Access and permissions:

  • Ensure administrative credentials for TMG, domain controllers, certificate stores, and the EE platform.
  • Verify service accounts, firewall management access, and remote console connectivity.

Preparing the TMG server

Before running the EE Single Server Conversion Tool:

• Update and patch: Apply the latest available updates to the TMG server to avoid bugs during export.
• Clean up configuration: Remove deprecated or unused objects (obsolete networks, stale user groups) to reduce clutter in the conversion output.
• Export certificates: Export SSL certificates (including private keys) that the target edge device will need. Verify expiration dates and renew if necessary.
• Disable services that might interfere (temporarily): If third-party antivirus or management agents could block the conversion tool, plan for temporary suspension.
• Export a TMG configuration backup: Use the TMG Management console to export the current configuration XML. Keep multiple copies stored securely.

Running the EE Single Server Conversion Tool

• Read the tool documentation thoroughly for version-specific requirements and known issues.
• Run the tool in “dry-run” or analysis mode first if available; review the report and generated mapping suggestions.
• Use a test/staging target to import the conversion output before touching production.
• Monitor logs closely; the tool typically produces a report listing converted items, skipped items, and recommended manual actions.
• Pay special attention to:
  • IP address mappings (especially translated NAT addresses).
  • Rule ordering and precedence — TMG’s policy processing order may not map exactly.
  • Authentication methods and user/group mappings.
  • Any TMG-specific inspection or protocol handling that the EE platform cannot reproduce automatically.

Post-conversion verification

After importing converted settings into the EE platform:

• Functional checks:

  • Verify internet access, internal-to-external connections, and NAT translations.
  • Test VPN connections (both site-to-site and client VPN) with representative clients.
  • Confirm authentication and single sign-on behavior for proxied services.

• Policy and security testing:

  • Run simulated traffic and penetration tests against common attack vectors to ensure protections are active.
  • Validate web filtering, content inspection, and protocol controls behave as expected.

• Performance and stability:

  • Monitor CPU, memory, throughput, and latency on the EE appliance under realistic load.
  • Compare performance metrics to baseline TMG performance to detect regressions.

• Certificate validation:

  • Verify SSL/TLS interception (if used), re-encryption, and certificate chains are correct for browsers and clients.
  • Ensure certificate pinning or client apps are not broken by the new TLS handling.

Manual adjustments and policy tuning

Expect manual work post-conversion:

• Reorder and refine rules: Policy order affects behavior. Use a conservative approach: start permissive where needed, then tighten.
• Recreate complex inspection rules: Some TMG inspection features (e.g., certain application-layer heuristics) may need manual translation.
• Reconfigure caching, compression, and content acceleration features according to the EE platform’s design.
• Update monitoring and logging: Point Syslog/SIEM feeds to the new device and validate log formats and parsing.

Minimizing downtime during cutover

To reduce user impact:

• Use staged cutover: Convert and validate in parallel with TMG running; switch traffic gradually via routing/DNS changes or by moving a subset of users first.
• Leverage NAT and VIPs: If possible, replicate public IPs and NAT settings on the new edge appliance so external services continue without client changes.
• Schedule during low-traffic windows and notify users of expected maintenance.
• Keep TMG in a fallback state (but isolated) until validation is complete.

Troubleshooting common issues

• Missing or malformed rules in output:

  • Compare the TMG export XML with the tool report to find skipped items.
  • Manually recreate rules when conversion logic doesn’t apply.

• VPN or authentication failures:

  • Check shared secrets, certificate trust chains, and authentication backend connectivity (AD/LDAP).
  • Confirm user group mappings and claims/attribute mappings for SSO integrations.

• Certificate errors on clients:

  • Ensure the new platform’s proxy certificate is trusted by corporate clients.
  • Reissue or re-import intermediate certificates if chains are incomplete.

• Performance degradations:

  • Profile traffic and enable hardware acceleration features on the EE device.
  • Adjust inspection depth or exclude high-throughput services from deep inspection.

Security and compliance considerations

• Retain audit trails: Ensure logs and event data required for compliance are preserved and forwarded to archival systems.
• Secure certificate handling: Protect private keys during export/import and follow organizational key management policies.
• Review access controls: Verify administrative access to the new appliance follows least-privilege principles and uses MFA where possible.

Rollback and post-migration cleanup

• Keep the TMG server available—but isolated—until the new platform is fully validated.
• Once stable, decommission TMG according to organizational change and asset disposal policies.
• Update documentation, runbooks, and diagrams to reflect the new network perimeter and policy flows.
• Train operations staff on the EE platform’s management, alerting, and recovery procedures.

Checklist (concise)

• Inventory TMG configs, networks, certificates.
• Build staging environment.
• Export TMG config and certificates.
• Run EE SSCT in dry-run; review report.
• Import into staging EE platform; validate.
• Gradual cutover; verify functionality, security, performance.
• Decommission TMG after successful validation.

The EE Single Server Conversion Tool can greatly accelerate a migration from Forefront TMG, but success depends on careful planning, testing, and manual tuning of converted policies. Treat the conversion as a significant change project: involve networking, security, identity, and application teams early, and validate thoroughly before final cutover.