# Security & Auth

> Source: `src/content/docs/agent-os/security.mdx`
> Canonical URL: https://rivet.dev/docs/agent-os/security
> Description: Configure resource limits, network control, authentication, and filesystem isolation for agentOS.

---
For the isolation model and trust boundaries, see [Security Model](/docs/agent-os/security-model).

## Resource limits

Restrict CPU and memory per actor to prevent runaway agents.

```ts @nocheck
import { agentOs } from "rivetkit/agent-os";
import { setup } from "rivetkit";
import common from "@rivet-dev/agent-os-common";
import pi from "@rivet-dev/agent-os-pi";

const vm = agentOs({
  options: {
    software: [common, pi],
    maxMemoryMb: 512,
    maxCpuPercent: 50,
  },
});

export const registry = setup({ use: { vm } });
registry.start();
```

## Network control

Control which ports and hosts the VM can access.

```ts @nocheck
import { agentOs } from "rivetkit/agent-os";
import { setup } from "rivetkit";
import common from "@rivet-dev/agent-os-common";

const vm = agentOs({
  options: {
    software: [common],
    loopbackExemptPorts: [8080, 3000],
  },
});

export const registry = setup({ use: { vm } });
registry.start();
```

## Custom authentication

Use the `onBeforeConnect` hook to validate clients before they access the agent.

```ts @nocheck
import { agentOs } from "rivetkit/agent-os";
import { setup } from "rivetkit";
import common from "@rivet-dev/agent-os-common";
import pi from "@rivet-dev/agent-os-pi";

const vm = agentOs({
  onBeforeConnect: async (c, params) => {
    const isValid = await verifyToken(params.token);
    if (!isValid) {
      throw new Error("Unauthorized");
    }
  },
  options: { software: [common, pi] },
});

export const registry = setup({ use: { vm } });
registry.start();

async function verifyToken(token: string): Promise<boolean> {
  // Your authentication logic
  return token === "valid-token";
}
```

## Permission system

Agents request permission before using tools. See [Permissions](/docs/agent-os/permissions) for auto-approve, selective approval, and human-in-the-loop patterns.

## Preview URL security

Preview URLs use randomly generated 32-character alphanumeric tokens with configurable expiration. See [Networking & Previews](/docs/agent-os/networking) for token management.

- Tokens are stored in SQLite and survive sleep/wake
- Expired tokens are automatically cleaned up
- Use `expireSignedPreviewUrl` to immediately revoke a token

## Filesystem isolation

Each VM has its own virtual filesystem. Files are isolated per actor instance.

- `/home/user` is persistent and survives sleep/wake
- Mount boundaries prevent escape via symlinks or path traversal
- Host directory mounts (if configured) prevent symlink escape beyond the mount point

_Source doc path: /docs/agent-os/security_
