# nsjail on Docker

<Callout type="info" title="Note">
  Agent Firewall is part of [AI Governance](/beta-docs/@main/ai-coder/ai-governance/), which is included with a Premium license.
</Callout>

This page describes the runtime and permission requirements for running Agent Firewall with the **nsjail** jail type on **Docker**.

For an overview of nsjail, see [nsjail](/beta-docs/@main/ai-coder/agent-firewall/nsjail/).

## Runtime & Permission Requirements for Running Boundary in Docker [#runtime--permission-requirements-for-running-boundary-in-docker]

This section describes the Linux capabilities and runtime configurations required to run Agent Firewall with nsjail inside a Docker container.
Requirements vary depending on the OCI runtime and the seccomp profile in use.

<div className="fd-steps">
  <div className="fd-step">
    ### Default `runc` runtime with `CAP_NET_ADMIN` [#default-runc-runtime-with-cap_net_admin]

    When using Docker's default `runc` runtime, Agent Firewall requires the container to have `CAP_NET_ADMIN`.
    This is the minimal capability needed for configuring virtual networking inside the container.

    Docker's default seccomp profile may also block certain syscalls (such as `clone`) required for creating unprivileged network namespaces.
    If you encounter these restrictions, you may need to update or override the seccomp profile to allow these syscalls.

    [see Docker Seccomp Profile Considerations](#docker-seccomp-profile-considerations)
  </div>

  <div className="fd-step">
    ### Default `runc` runtime with `CAP_SYS_ADMIN` (testing only) [#default-runc-runtime-with-cap_sys_admin-testing-only]

    For development or testing environments, you may grant the container `CAP_SYS_ADMIN`, which implicitly bypasses many of the restrictions in Docker's default seccomp profile.

    * Agent Firewall does not require `CAP_SYS_ADMIN` itself.
    * However, Docker's default seccomp policy commonly blocks namespace-related syscalls unless `CAP_SYS_ADMIN` is present.
    * Granting `CAP_SYS_ADMIN` enables Agent Firewall to run without modifying the seccomp profile.

    ⚠️ Warning: `CAP_SYS_ADMIN` is extremely powerful and should not be used in production unless absolutely necessary.
  </div>
</div>

### 3. `sysbox-runc` runtime with `CAP_NET_ADMIN` [#3-sysbox-runc-runtime-with-cap_net_admin]

When using the `sysbox-runc` runtime (from Nestybox), Agent Firewall can run with only:

* `CAP_NET_ADMIN`

The sysbox-runc runtime provides more complete support for unprivileged user namespaces and nested containerization, which typically eliminates the need for seccomp profile modifications.

## Docker Seccomp Profile Considerations [#docker-seccomp-profile-considerations]

Docker's default seccomp profile frequently blocks the `clone` syscall, which is required by Agent Firewall when creating unprivileged network namespaces.
If the `clone` syscall is denied, Agent Firewall will fail to start.

To address this, you may need to modify or override the seccomp profile used by your container to explicitly allow the required `clone` variants.

You can find the default Docker seccomp profile for your Docker version here (specify your docker version):

[https://github.com/moby/moby/blob/v25.0.13/profiles/seccomp/default.json#L628-L635](https://github.com/moby/moby/blob/v25.0.13/profiles/seccomp/default.json#L628-L635)

If the profile blocks the necessary `clone` syscall arguments, you can provide a custom seccomp profile that adds an allow rule like the following:

```json
{
    "names": ["clone"],
    "action": "SCMP_ACT_ALLOW"
}
```

This example unblocks the clone syscall entirely.

### Example: Overriding the Docker Seccomp Profile [#example-overriding-the-docker-seccomp-profile]

To use a custom seccomp profile, start by downloading the default profile for your Docker version:

[https://github.com/moby/moby/blob/v25.0.13/profiles/seccomp/default.json#L628-L635](https://github.com/moby/moby/blob/v25.0.13/profiles/seccomp/default.json#L628-L635)

Save it locally as seccomp-v25.0.13.json, then insert the clone allow rule shown above (or add "clone" to the list of allowed syscalls).

Once updated, you can run the container with the custom seccomp profile:

```sh
docker run -it \
  --cap-add=NET_ADMIN \
  --security-opt seccomp=seccomp-v25.0.13.json \
  test bash
```

This instructs Docker to load your modified seccomp profile while granting only the minimal required capability (`CAP_NET_ADMIN`).