Simplifying FedRAMP Compliance with Teleport
Jun 27
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Teleport

Set Up Login Rules

This guide will walk you through the process of writing, testing, and adding the first Login Rule to your Teleport cluster.

Prerequisites

  • A running Teleport cluster. If you want to get started with Teleport, sign up for a free trial.

  • The tctl admin tool and tsh client tool version >= 16.0.1.

    Visit Installation for instructions on downloading tctl and tsh.

  • 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 16.0.1

    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.

Before you get started you’ll need a running Teleport Enterprise or Cloud cluster on version 11.3.1 or greater.

Login Rules only operate on SSO logins, so make sure you have configured an OIDC, SAML, or GitHub connector before you begin. Check the Single Sign-On docs to learn how to set this up.

Step 1/5. Configure RBAC

First, ensure you are logged into Teleport as a user that has permissions to read and modify login_rule resources. The preset editor role has access to this already, but in case you are using a more customized configuration, create a role called loginrule-manager.yaml with the following contents:

kind: role
metadata:
  name: loginrule-manager
spec:
  allow:
    rules:
      - resources: [login_rule]
        verbs: [list, create, read, update, delete]
version: v7

Create the role with tctl:

tctl create loginrule-manager.yaml
role 'loginrule-manager' has been created

Assign the loginrule-manager role to your Teleport user by running the appropriate commands for your authentication provider:

  1. Retrieve your local user's roles as a comma-separated list:

    ROLES=$(tsh status -f json | jq -r '.active.roles | join(",")')
  2. Edit your local user to add the new role:

    tctl users update $(tsh status -f json | jq -r '.active.username') \ --set-roles "${ROLES?},loginrule-manager"
  3. Sign out of the Teleport cluster and sign in again to assume the new role.

  1. Retrieve your github authentication connector:

    tctl get github/github --with-secrets > github.yaml

    Note that the --with-secrets flag adds the value of spec.signing_key_pair.private_key to the github.yaml file. Because this key contains a sensitive value, you should remove the github.yaml file immediately after updating the resource.

  2. Edit github.yaml, adding loginrule-manager to the teams_to_roles section.

    The team you should map to this role depends on how you have designed your organization's role-based access controls (RBAC). However, the team must include your user account and should be the smallest team possible within your organization.

    Here is an example:

      teams_to_roles:
        - organization: octocats
          team: admins
          roles:
            - access
    +       - loginrule-manager
    
  3. Apply your changes:

    tctl create -f github.yaml
  4. Sign out of the Teleport cluster and sign in again to assume the new role.

  1. Retrieve your saml configuration resource:

    tctl get --with-secrets saml/mysaml > saml.yaml

    Note that the --with-secrets flag adds the value of spec.signing_key_pair.private_key to the saml.yaml file. Because this key contains a sensitive value, you should remove the saml.yaml file immediately after updating the resource.

  2. Edit saml.yaml, adding loginrule-manager to the attributes_to_roles section.

    The attribute you should map to this role depends on how you have designed your organization's role-based access controls (RBAC). However, the group must include your user account and should be the smallest group possible within your organization.

    Here is an example:

      attributes_to_roles:
        - name: "groups"
          value: "my-group"
          roles:
            - access
    +       - loginrule-manager
    
  3. Apply your changes:

    tctl create -f saml.yaml
  4. Sign out of the Teleport cluster and sign in again to assume the new role.

  1. Retrieve your oidc configuration resource:

    tctl get oidc/myoidc --with-secrets > oidc.yaml

    Note that the --with-secrets flag adds the value of spec.signing_key_pair.private_key to the oidc.yaml file. Because this key contains a sensitive value, you should remove the oidc.yaml file immediately after updating the resource.

  2. Edit oidc.yaml, adding loginrule-manager to the claims_to_roles section.

    The claim you should map to this role depends on how you have designed your organization's role-based access controls (RBAC). However, the group must include your user account and should be the smallest group possible within your organization.

    Here is an example:

      claims_to_roles:
        - name: "groups"
          value: "my-group"
          roles:
            - access
    +       - loginrule-manager
    
  3. Apply your changes:

    tctl create -f oidc.yaml
  4. Sign out of the Teleport cluster and sign in again to assume the new role.

Step 2/5. Draft your Login Rule resource

The following example will give all users a new logins trait set to the value of their current username trait converted to lowercase. Copy this example rule to a file called my_rule.yaml to continue with the guide.

# my_rule.yaml
kind: login_rule
version: v1
metadata:
  # Each Login Rule must have a unique name within the cluster.
  name: my_rule

  # expires is optional and usually should not be set for deployed login
  # rules, but it can be useful to set an expiry a short time in the future
  # while testing new Login Rules to prevent potentially locking yourself out of
  # your Teleport cluster.
  # expires: "2023-01-31T00:00:00-00:00"
spec:
  # priority orders the evaluation of Login Rules if multiple are present in the
  # cluster, lower priorities are evaluated first.
  priority: 0

  # traits_expression is a predicate expression which will be evaluated to
  # determine the final traits for each SSO user during login.
  #
  # This example expression sets the "logins" trait to the incoming "username"
  # trait converted to lowercase.
  traits_expression: 'external.put("logins", strings.lower(external["username"]))'

Each Login Rule resource must have either a traits_map or traits_expression field. In this guide we will use an example traits_expression.

The traits_expression is a form of script which will be evaluated by your Teleport cluster at runtime to determine the traits for each SSO user who logs in. The expression can access the incoming traits for the user via the external variable. The external variable is a dictionary which maps trait keys to sets of values for that trait.

Step 3/5. Test the Login Rule

The tctl login_rule test command can be used to experiment with new Login Rules to check their syntax and see exactly how they will operate on example incoming traits.

Fetch your user's current traits and store them in input.json, then test your new Login Rule with that input.

tctl get --format json users/username | jq 'first.spec.traits' > input.json
tctl login_rule test --resource-file my_rule.yaml input.json
access:- staginggroups:- dbs- devslogins:- alice

This script will catch any syntax errors in your expressions. Make sure that all expected traits are present in the output.

Step 4/5. Create the Login Rule

Use the following command to create the Login Rule in your cluster:

tctl create my_rule.yaml

Step 5/5. Try it out

As a final step, log out of your cluster, then log in again and make sure your user received the expected traits and roles. You can check the traits and roles with the following command:

tctl get --format json users/username | jq '{traits: first.spec.traits, roles: first.spec.roles}'
{ "traits": { "access": [ "staging" ], "groups": [ "dbs", "devs" ], "logins": [ "alice" ] }, "roles": [ "access", "editor", "auditor" ]}

Troubleshooting

The tctl sso test command can be used to debug SSO logins and see exactly which traits are being sent by your SSO provider and how they are being mapped by your Login Rules.

tctl sso test expects a connector spec. Run the following command to debug with a connector currently installed in your cluster.

tctl get connector/SSO connector name --with-secrets | tctl sso test

Next steps

To learn more about the Login Rule expression syntax, check out the Login Rule Reference page.

Learn about the tctl login_rule test command by running the help command or checking the reference page.

tctl help login_rule test

The following tctl resource commands are helpful for viewing and modifying the login rules currently installed in your cluster.

CommandDescription
tctl get login_rulesShow all Login Rules installed in your cluster.
tctl get login_rule/<rule_name>Get a specific installed Login Rule.
tctl create login_rule.yamlInstall a new Login Rule.
tctl create -f login_rule.yamlOverwrite an existing Login Rule.
tctl rm login_rule/<rule_name>Delete a Login Rule.

Example Login Rules

Set a trait to a static list of values defined per group

kind: login_rule
version: v1
metadata:
  name: example
spec:
  priority: 0
  traits_expression: |
    external.put("allow-env",
      choose(
        option(external.group.contains("dev"), set("dev", "staging")),
        option(external.group.contains("qa"), set("qa", "staging")),
        option(external.group.contains("admin"), set("dev", "qa", "staging", "prod")),
        option(true, set()),
      ))

Use only specific traits provided by the OIDC/SAML provider

To only keep the groups and email traits, with their original values:

kind: login_rule
version: v1
metadata:
  name: example
spec:
  priority: 0
  traits_map:
    groups:
      - external.groups
    email:
      - external.email

Remove a specific trait

To remove a specific trait and keep the rest:

kind: login_rule
version: v1
metadata:
  name: example
spec:
  priority: 0
  traits_expression: |
    external.remove("big-trait")

Extend a specific trait with extra values

kind: login_rule
version: v1
metadata:
  name: example
spec:
  priority: 0
  traits_expression: |
    external.add_values("logins", "ubuntu", "ec2-user")

Use the output of one Login Rule in another rule

kind: login_rule
version: v1
metadata:
  name: set_groups
spec:
  priority: 0
  traits_expression: |
    external.put("groups",
      ifelse(external.groups.contains("admins"),
        external["groups"].add("superusers"),
        external["groups"]))
---
kind: login_rule
version: v1
metadata:
  name: set_logins
spec:
  priority: 1
  traits_expression: |
    ifelse(external.groups.contains("superusers"),
      external.add_values("logins", "root"),
      external)