Boundary provides simple and secure access to hosts and services.

Traditional approaches like SSH bastion hosts or VPNs require distributing and managing credentials, configuring network controls like firewalls, and exposing the private network. Boundary provides a secure way to access hosts and critical systems without having to manage credentials or expose your network, and is entirely open source.

Boundary is designed to be straightforward to understand, highly scalable, and resilient. It can run in clouds, on-prem, secure enclaves and more, and does not require an agent to be installed on every end host.

Unlike firewalls, Boundary performs per-access authentication and authorization checks, allowing for much higher level mappings of users to services or hosts than at network layers. Although complementary to secrets managers (like HashiCorp's own Vault), Boundary fills a different niche, allowing the credential that is eventually used to be hidden entirely from the user.

Getting Started

Boundary consists of two server components: Controllers, which serve the API and coordinate session requests; and Workers, which perform the actual session handling. A normal Boundary installation will consist of one or more Controllers paired with one or more Workers. A single Boundary binary can act in either of these two modes.

Additionally, Boundary provides a client that provides access to request and connect to authorized sessions.

Boundary does not require software to be installed on the endpoint hosts and services.


Boundary has two external dependencies: a SQL database, and one or more KMSes. Both are readily available from cloud vendors, but can be satisfied by on-premises technologies as well.

  • The database contains Boundary's configuration and session information and must be accessible by Controller nodes. Values that are secrets (such as credentials) are encrypted in the database. Currently, PostgreSQL is supported as a database and has been tested with Postgres 11 and above. Boundary uses only common extensions and both hosted and self-run instances are supported. In most instances all that is needed is a database endpoint and appropriate credentials.
  • Any cloud KMS or Vault's Transit Secrets Engine can be used to satisfy the KMS requirement. Currently, two keys within the KMS are required: one for authenticating other cluster components, which must be accessible by both Controllers and Workers; and one for encrypting secret values in the database, which need only be accessible to Controllers. These keys can be changed over time (so long as the original key remains available for any decryption needs), and key derivation is used extensively to avoid key sprawl of these high-value keys. If available, other keys can be used for other purposes, such as recovery functionality and encryption of sensitive values in Boundary's config file.

Boundary has a dev mode that can be used for testing. In this mode both a Controller and Worker are started with a single command, and they have the following properties:

  • The Controller will start a PostgreSQL Docker container to use as storage. This container will be shut down and removed (if possible) when the Controller is (gracefully) shut down.
  • The Controller will use an internal KMS with ephemeral keys

Trying out Boundary

Running Boundary in a more permanent context requires a few more steps, such as writing some simple configuration files to tell the nodes how to reach their database and KMS. The steps below, along with the extra information needed for permanent installations, are detailed in our Installation Guide.

Build and Start Boundary in Dev Mode

If you have the following requirements met locally:

  • Golang v1.14 or greater
  • Docker

You can get up and running with Boundary quickly. Simply run:

make dev

This will build Boundary. (The first time this is run it will fetch and compile UI assets; which will take a few extra minutes.) Once complete, run Boundary in dev mode:

./$GOPATH/bin/boundary dev

Please note that building the UI requires go-bindata; the easiest way to install Boundary's dependent tools is to simply run:

make tools

Without doing so, you may encounter errors while running make dev. It is important to also note that using make tools will install various tools used for Boundary development to the normal Go binary directory; this may overwrite or take precedence over tools that might already be installed on the system.

Specify a UI Commitish at Build Time

By default the UI will be built from a preselected commit ID from the UI repo. A different commitish from which to build UI assets may be specified via the UI_COMMITISH environment variable. For example:

UI_COMMITISH=feature-branch make build-ui

will update your local UI assets.

UI Build Troubleshooting

UI assets are built within a Docker container. If you encounter issues with this build step, trying increasing memory and swap available to Docker.

UI Development

It would be impractical to rebuild the binary on every change when actively developing the UI. To make UI development more convenient, the binary supports a passthrough directory. This is an arbitrary local directory from which UI assets are served. Note this option is only available in dev mode. For example:

BOUNDARY_DEV_PASSTHROUGH_DIRECTORY=/boundary-ui/ui/core/dist ~/go/bin/boundary dev

Download and Run from Release Page

Download the latest release of the server binary and appropriate desktop client(s) from our releases page

Start Boundary

Start the server binary with:

boundary dev

This will start a Controller service listening on for incoming API requests and a Worker service listening on for incoming session requests. It will also create various default resources and display various useful pieces of information, such as a login name and password that can be used to authenticate.

Configuring Resources

For a simple test of Boundary in dev mode you don't generally need to configure any resources at all! But it's useful to understand what dev mode did for you so you can then take further steps. By default, dev mode will create:

  • The global Scope for initial authentication, containing a Password-type Auth Method, along with an Account for login.
  • An organization Scope under global, and a project Scope inside the organization.
  • A Host Catalog with a default Host Set, which itself contains a Host with the address of the local machine (
  • A Target mapping the Host Set to a set of connection parameters, with a default port of 22 (e.g. SSH)

You can of course go into Boundary's web UI or use its API to change these default values, for instance if you want to connect to a different host or need to modify the port on which to to connect.

Making the Connection

Next, let's actually make a connection to your local SSH daemon via Boundary:

  1. Authenticate to Boundary; using default dev values, this would be boundary authenticate password -auth-method-id ampw_1234567890 -login-name admin -password password. (Note that if you do not include the password flag you will be prompted for it.)
  2. Run boundary connect ssh -target-id ttcp_1234567890. If you want to adjust the username, pass -username <name> to the command.

A lot more is possible with Boundary, even at this early stage. Check out the possibilities for target configuration to test out limiting (or increasing) the number of connections per session or setting a maximum time limit; try canceling an active session from the sessions page or via boundary sessions, make your own commands with boundary connect -exec, and so on.

Going Further

This example is a simple way to get started but omits several key steps that could be taken in a production context:

  • Using a firewall or other means to restrict the set of hosts allowed to connect to a local service to only Boundary Worker nodes, thereby making Boundary the only means of ingress to a host
  • Using the Boundary Terraform provider to easily integrate Boundary with your existing code-based infrastructure
  • Pointing a BI tool (PowerBI, Tableau, etc.) at Boundary's session warehouse to generate insights and look for anomalies with respect to session access

There are many, many more things that Boundary will do in the future in terms of integrations, features, and more. We have a long roadmap planned out, so stay tuned for information about new features and capabilities!