> ## Documentation Index
> Fetch the complete documentation index at: https://ngrok.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Error 393

## ERR\_NGROK\_393

When specifying CIDRs to deny, you must specify at least one CIDR to allow. Otherwise all traffic will be denied. Use 0.0.0.0/0 and ::0/0 to accept all traffic not explicitly blocked by your deny rules.

## Further help

If you're having trouble resolving this error, please reach out to [support@ngrok.com](mailto:support@ngrok.com?subject=Help%20with%20ERR_NGROK_393)