Teleport 16: Advancing Infrastructure Defense in Depth with Device Trust, MFA, and VNET
Jul 25
Virtual
Register Today
Teleport logoTry For Free
Fork me on GitHub

Teleport

Server Access Getting Started Guide

Teleport SSH Server Access Demo

Teleport SSH Server Access Demo

Length: 06:45

You can protect a server with Teleport by running the Teleport SSH Service on the server and enrolling it in your Teleport cluster. Once the server has joined your cluster, the Teleport RBAC system enforces secure access to the server, and administrators can identify security threats using the Teleport audit log.

The Teleport SSH Service opens a reverse SSH tunnel to the Teleport Proxy Service, and SSH client traffic uses this tunnel to connect to a server. This setup is similar to the bastion pattern.

This guides shows you how to:

  • Enroll a server in your Teleport cluster.
  • SSH into a server using Teleport.
  • Inspect server resources in the cluster using Teleport commands.

You can use Teleport to enable secure access to a Kubernetes node. To do so, modify your node's machine image to install and run the Teleport SSH Service as per the instructions in this guide. Do not run the SSH Service as a Kubernetes pod, as there is no guarantee that the SSH Service pod is running on a server that a user intends to access.

Teleport Bastion

Prerequisites

  • A running Teleport cluster version 16.1.0 or above. If you want to get started with Teleport, sign up for a free trial or set up a demo environment.

  • The tctl admin tool and tsh client tool.

    Visit Installation for instructions on downloading tctl and tsh.

  • One host running a Linux environment (such as Ubuntu 20.04, CentOS 8.0, or Debian 10). This will serve as a Teleport Node.
  • To check that you can connect to your Teleport cluster, sign in with tsh login, then verify that you can run tctl commands using your current credentials. tctl is supported on macOS and Linux machines. For example:
    tsh login --proxy=teleport.example.com --user=[email protected]
    tctl status

    Cluster teleport.example.com

    Version 16.1.0

    CA pin sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678

    If you can connect to the cluster and run the tctl status command, you can use your current credentials to run subsequent tctl commands from your workstation. If you host your own Teleport cluster, you can also run tctl commands on the computer that hosts the Teleport Auth Service for full permissions.

When running Teleport in production, you should adhere to the following best practices to avoid security incidents:

  • Avoid using sudo in production environments unless it's necessary.
  • Create new, non-root, users and use test instances for experimenting with Teleport.
  • Run Teleport's services as a non-root user unless required. Only the SSH Service requires root access. Note that you will need root permissions (or the CAP_NET_BIND_SERVICE capability) to make Teleport listen on a port numbered < 1024 (e.g. 443).
  • Follow the principle of least privilege. Don't give users permissive roles when more a restrictive role will do. For example, don't assign users the built-in access,editor roles, which give them permissions to access and edit all cluster resources. Instead, define roles with the minimum required permissions for each user and configure access requests to provide temporary elevated permissions.
  • When you enroll Teleport resources—for example, new databases or applications—you should save the invitation token to a file. If you enter the token directly on the command line, a malicious user could view it by running the history command on a compromised system.

You should note that these practices aren't necessarily reflected in the examples used in documentation. Examples in the documentation are primarily intended for demonstration and for development environments.

Step 1/4. Install Teleport on your Linux host

  1. Your Linux host will be a private resource. Open port 22 so you can initially access, configure, and provision your instance.

    We'll configure and launch our instance, then demonstrate how to use the tsh tool and Teleport in SSH mode.

  2. On the host where you will run the Teleport SSH Service, follow the instructions for your environment to install Teleport.

    Install Teleport on your Linux server:

    1. Assign edition to one of the following, depending on your Teleport edition:

      EditionValue
      Teleport Enterprise Cloudcloud
      Teleport Enterprise (Self-Hosted)enterprise
      Teleport Community Editionoss
    2. Get the version of Teleport to install. If you have automatic agent updates enabled in your cluster, query the latest Teleport version that is compatible with the updater:

      TELEPORT_DOMAIN=example.teleport.com
      TELEPORT_VERSION="$(curl https://$TELEPORT_DOMAIN/v1/webapi/automaticupgrades/channel/default/version | sed 's/v//')"

      Otherwise, get the version of your Teleport cluster:

      TELEPORT_DOMAIN=example.teleport.com
      TELEPORT_VERSION="$(curl https://$TELEPORT_DOMAIN/v1/webapi/ping | jq -r '.server_version')"
    3. Install Teleport on your Linux server:

      curl https://goteleport.com/static/install.sh | bash -s ${TELEPORT_VERSION} edition

      The installation script detects the package manager on your Linux server and uses it to install Teleport binaries. To customize your installation, learn about the Teleport package repositories in the installation guide.

    Next, we'll create a join token so you can start the Teleport SSH Service and add it to your cluster.

Step 2/4. Add a server to the cluster

Create a join token

On your local workstation, create a join token so you can add the server to your Teleport cluster:

Let's save the token to a file
tctl tokens add --type=node --format=text > token.file
Let's save the token to a file
tctl tokens add --type=node --format=text > token.file

--type=node specifies that the Teleport process will act and join as an SSH server.

> token.file indicates that you'd like to save the output to a file name token.file.

Tip

This helps to minimize the direct sharing of tokens even when they are dynamically generated.

Join your server to the cluster

On your server, save token.file to an appropriate, secure, directory you have the rights and access to read. Next, generate a configuration file enabling Teleport's SSH Service.

Change tele.example.com to the address of your Teleport Proxy Service. Assign the --token flag to the path where you saved token.file.

Generate config

sudo teleport node configure \ --output=file:///etc/teleport.yaml \ --token=/path/to/token.file \ --proxy=tele.example.com:443

Change mytenant.teleport.sh to your Teleport Cloud tenant address. Assign the --token flag to the path where you saved token.file.

Generate config

sudo teleport node configure \ --output=file:///etc/teleport.yaml \ --token=/path/to/token.file \ --proxy=mytenant.teleport.sh:443

The teleport node configure command above placed a configuration file at /etc/teleport.yaml. The last step is to start Teleport, pointing it at this configuration:

Configure the Teleport SSH Service to start automatically when the host boots up by creating a systemd service for it. The instructions depend on how you installed the Teleport SSH Service.

On the host where you will run the Teleport SSH Service, enable and start Teleport:

sudo systemctl enable teleport
sudo systemctl start teleport

On the host where you will run the Teleport SSH Service, create a systemd service configuration for Teleport, enable the Teleport service, and start Teleport:

sudo teleport install systemd -o /etc/systemd/system/teleport.service
sudo systemctl enable teleport
sudo systemctl start teleport

You can check the status of the Teleport SSH Service with systemctl status teleport and view its logs with journalctl -fu teleport.

Access the Web UI

Run the following command to create a user that can access the Teleport Web UI:

tctl users add myuser --roles=editor,access --logins=root,ubuntu,ec2-user

This will generate an initial login link where you can create a password and set up multi-factor authentication for myuser.

Note

We've only given myuser the roles editor and access according to the Principle of Least Privilege.

You should now be able to view your server in the Teleport Web UI after logging in as myuser:

Both servers in the Web UI

Step 3/4. SSH into the server

Now that we've got our cluster up and running, let's see how easy it is to connect to our server.

We can use tsh to SSH into the cluster:

Log in to the cluster

On your local machine, log in to your cluster through tsh, assigning the --proxy flag to the address of your Teleport Proxy Service:

Log in through tsh

tsh login --proxy=tele.example.com --user=myuser

On your local machine, log in to your cluster through tsh, assigning the --proxy flag to the address of your Teleport Cloud tenant:

Log in through tsh

tsh login --proxy=mytenant.teleport.sh:443 --user=myuser

You'll be prompted to supply the password and second factor we set up previously.

myuser will now see something similar to:

> Profile URL:      https://tele.example.com:443
Logged in as:       myuser
Cluster:            tele.example.com
Roles:              access, editor
Logins:             root, ubuntu, ec2-user
Kubernetes:         disabled
Valid until:        2021-04-30 06:39:13 -0500 CDT [valid for 12h0m0s]
Extensions:         permit-agent-forwarding, permit-port-forwarding, permit-pty

In this example, myuser is now logged into the tele.example.com cluster through Teleport SSH.

> Profile URL:        https://mytenant.teleport.sh:443
Logged in as:       myuser
Cluster:            mytenant.teleport.sh
Roles:              access, editor
Logins:             root, ubuntu, ec2-user
Kubernetes:         disabled
Valid until:        2021-04-30 06:39:13 -0500 CDT [valid for 12h0m0s]
Extensions:         permit-agent-forwarding, permit-port-forwarding, permit-pty

In this example, myuser is now logged into the mytenant.teleport.sh cluster through Teleport SSH.

Display cluster resources

myuser can now execute the following to find the cluster's server names, which are used for establishing SSH connections:

Display cluster resources

tsh ls

In this example, the bastion host is located on the bottom line below:

Node Name        Address        Labels
---------------- -------------- --------------------------------------
ip-172-31-35-170 ⟵ Tunnel
ip-172-31-41-144 127.0.0.1:3022 env=example, hostname=ip-172-31-41-144

Connect to a server

myuser can SSH into the bastion host server by running the following command locally:

Use tsh to ssh into a server

tsh ssh root@ip-172-31-41-144

Now, they can:

  • Connect to other servers in the cluster by using the appropriate IP address in the tsh ssh command.
  • Traverse the Linux file system.
  • Execute desired commands.

All commands executed by myuser are recorded and can be replayed in the Teleport Web UI.

The tsh ssh command allows users to do anything they could if they were to SSH into a server using a third-party tool. Compare the two equivalent commands:

tsh ssh root@ip-172-31-41-144

To use the ssh client generate a SSH configuration file and postfix the cluster name after the node name.

tsh config > ssh_config_teleport
ssh -F ssh_config_teleport [email protected]

Step 4/4. Use tsh and the unified resource catalog to introspect the cluster

Now, myuser has the ability to SSH into other servers within the cluster, traverse the Linux file system, and execute commands.

  • They have visibility into all resources within the cluster due to their defined and assigned roles.
  • They can also quickly view any server or grouping of servers that have been assigned a particular label.

Display the unified resource catalog

Execute the following command within your bastion host console:

List servers

tctl nodes ls

This displays the unified resource catalog with all queried resources in one view:

Nodename         UUID                                 Address        Labels
---------------- ------------------------------------ -------------- -------------------------------------
ip-172-31-35-170 4980899c-d260-414f-9aea-874feef71747
ip-172-31-41-144 f3d2a65f-3fa7-451d-b516-68d189ff9ae5 127.0.0.1:3022 env=example,hostname=ip-172-31-41-144

Note the "Labels" column on the farthest side. myuser can query all resources with a shared label using the command:

Query all servers with a label

tsh ls env=example

Customized labels can be defined in your teleport.yaml configuration file or during server creation.

This is a convenient feature that allows for more advanced queries. If an IP address changes, for example, an admin can quickly find the current server with that label since it remains unchanged.

Run commands on all servers with a label

myuser can also execute commands on all servers that share a label, vastly simplifying repeated operations. For example, the following command will execute the ls command on each server and display the results in your terminal:

Run the ls command on all servers with a label

tsh ssh root@env=example ls

Optional: Harden your server

We previously configured our Linux instance to leave port 22 open to easily configure and install Teleport. Feel free to compare Teleport SSH to your usual ssh commands.

To harden your Teleport server:

  • Close port 22 on your private Linux instance now that your Teleport server is configured and running.
  • For self-hosted deployments, optionally close port 22 on your Proxy Service host.
  • You'll be able to fully connect to the private instance and, for self-hosted deployments, the Proxy Service host, using tsh ssh.

Conclusion

To recap, this guide described:

  • How to set up and add an SSH server to a cluster.
  • Connect to the cluster using tsh to manage and introspect resources.

Feel free to shut down, clean up, and delete your resources, or use them in further Getting Started exercises.

Next steps

Resources