OpenAI began blocking API connections from China in July 2024. Since then, enforcement has intensified: known VPN IP ranges are blocklisted, and connections from flagged IPs trigger account reviews. For developers using Codex CLI from China, the risk is real and the consequences are permanent.

OpenAI's Detection Methods

OpenAI uses several methods to detect China-based access:

  • IP geolocation: Connections from Chinese IP ranges are blocked at the API level
  • VPN IP blocklists: OpenAI maintains lists of IPs associated with NordVPN, ExpressVPN, Astrill, and other commercial VPN providers
  • Behavioral analysis: Unusual connection patterns (frequent IP changes, connections from multiple countries in short timeframes) trigger reviews

Safe Setup for Codex CLI

Requirements

  • VPN with TUN mode (CLI tools bypass browser proxies)
  • Kill switch (prevents IP exposure during disconnections)
  • Private IP not in any commercial VPN blocklist
  • Consistent server location (avoid frequent IP/location changes)

Step-by-Step

  1. Connect VPN with TUN mode and kill switch enabled
  2. Verify public IP shows a non-China, non-VPN address: curl ifconfig.me
  3. Launch terminal and use Codex normally: openai codex --prompt "your prompt"
  4. Keep VPN active for the entire session
  5. Close Codex before disconnecting VPN

What to Avoid

  • Never use Codex without VPN active and verified
  • Never switch VPN servers mid-session (IP change triggers behavioral flags)
  • Never use a shared commercial VPN IP (already on blocklists)
  • Never run Codex during VPN reconnection

If Your Account Gets Flagged

OpenAI's enforcement includes: API request rejection (immediate), account review notification (email within 24-48 hours), and potential account termination. If you receive a review notification, stop all API access immediately and contact OpenAI support with documentation of legitimate use.

Prevention is the only reliable strategy. Account recovery after a China IP detection is not guaranteed. Invest in proper VPN setup before you need it. KookVPN's AI developer protection includes TUN mode, kill switch, and a private IP that is not on any VPN blocklist.

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