---
title: "Require tokens for the metadata service · Agent Wranglers"
url: https://agentwranglers.se/playbook/infrastructure/networking-and-dns/metadata-service-tokens
updated: 2026-10-20
licence: "All rights reserved"
---

# Require tokens for the metadata service

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Required
- Chapter: [Networking and DNS](https://agentwranglers.se/playbook/infrastructure/networking-and-dns)
- Rule: Make every cloud server's metadata service answer only requests that carry a session token. Allow the token to travel one network hop, or two when containers on the host need it.
- How: The metadata address hands out the machine's credentials. A [server-side request forgery](https://agentwranglers.se/playbook/adversarial-testing/requests-and-files/block-server-side-request-forgery) hole can read it with a plain GET. On AWS, require IMDSv2 with `http_tokens = "required"` and a hop limit of 1. Use 2 when containers on the host need it. Google Cloud and Azure already require a special header, `Metadata-Flavor: Google` or `Metadata: true`. Set the account default in every region too, so new servers start safe.
- Check: The query below lists no instance with tokens optional. No instance has a hop limit above 2. From the server, a GET to `169.254.169.254` without a token gets 401.

Example:

```hcl
resource "aws_instance" "web" {
  ami           = data.aws_ami.web.id
  instance_type = "t4g.small"
  metadata_options {
    http_tokens                 = "required"
    http_put_response_hop_limit = 1
  }
}
```

```hcl
# The default for every new server in this region
resource "aws_ec2_instance_metadata_defaults" "baseline" {
  http_tokens                 = "required"
  http_put_response_hop_limit = 1
}
```

```sh
aws ec2 describe-instances --query 'Reservations[].Instances[?MetadataOptions.HttpTokens==`optional`].InstanceId' --output text   # empty
curl -s -o /dev/null -w '%{http_code}\n' http://169.254.169.254/latest/meta-data/   # 401
```

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers infrastructure playbook: https://agentwranglers.se/playbook/infrastructure/networking-and-dns/metadata-service-tokens`.

- Previous: [Force encryption on every managed service](https://agentwranglers.se/playbook/infrastructure/networking-and-dns/enforce-tls-on-services)
- Next: [Keep DNS records in code](https://agentwranglers.se/playbook/infrastructure/networking-and-dns/dns-as-code)
- [Networking and DNS](https://agentwranglers.se/playbook/infrastructure/networking-and-dns)