Skip to content

Latest commit

 

History

History
833 lines (616 loc) · 29.4 KB

admin-guide.md

File metadata and controls

833 lines (616 loc) · 29.4 KB
Raw

Admin Manual

This manual covers installation and configuration of Teleport and the ongoing management of a Teleport cluster. It assumes that the reader has good understanding of Linux administration.

Installation

Installing from Source

Gravitational Teleport is written in Go language. It requires Golang v1.7 or newer. If you have Go already installed, type:

$ go get github.com/gravitational/teleport
$ cd $GOPATH/src/github.com/gravitational/teleport
$ make

Installing from Binaries

You can download binaries from Github releases.

Nomenclature

Before diving into configuring and running Teleport, it helps to take a look at the Teleport Architecture and go over the key concepts this document will be referring to:

Concept Description
Node Synonym to "server" or "computer", something one can "SSH to". A node must be running teleport daemon running with "node" role/service turned on.
Certificate Authority (CA) A pair of public/private keys Teleport uses to manage access. A CA can sign a public key of a user or node establishing their cluster membership.
Teleport Cluster A Teleport Auth Service contains two CAs. One is used to sign user keys and the other signs node keys. A collection of nodes connected to the same CA is called a "cluster".
Cluster Name Every Teleport cluster must have a name. If a name is not supplied via teleport.yaml configuration file, a GUID will be generated. IMPORTANT: renaming a cluster invalidates its keys and all certificates it had created.
Trusted Cluster Teleport Auth Service can allow 3rd party users or nodes to connect if their public keys are signed by a trusted CA. A "trusted cluster" is a pair of public keys of the trusted CA. It can be configured via teleport.yaml file.

Running Teleport Servers

The Teleport daemon supports the following commands:

Command Description
start Starts the Teleport daemon.
configure Dumps a sample configuration file in YAML format into standard output.
version Shows the Teleport version.
status Shows the status of a Teleport connection. This command is only available from inside of an active SSH session.
help Shows help.

When experimenting you can quickly start teleport with verbose logging by typing teleport start -d.

!!! danger "WARNING": Teleport stores data in /var/lib/teleport. Make sure that regular users do not have access to this folder on the Auth server.

Systemd Unit File

In production, we recommend starting teleport daemon via an init system like systemd. Here's the example of a systemd unit file:

[Unit]
Description=Teleport SSH Service
After=network.target 

[Service]
Type=simple
Restart=always
ExecStart=/usr/local/bin/teleport start --config=/etc/teleport.yaml

[Install]
WantedBy=multi-user.target

Ports

Teleport services listen on several ports. This table shows the default port numbers.

Port Service Description
3022 Node SSH port. This is Teleport's equivalent of port #22 for SSH.
3023 Proxy SSH port clients connect to. A proxy will forward this connection to port #3022 on the destination node.
3024 Proxy SSH port used to create "reverse SSH tunnels" from behind-firewall environments into a trusted proxy server.
3025 Auth SSH port used by the Auth Service to serve its API to other nodes in a cluster.
3080 Proxy HTTPS connection to authenticate tsh users and web users into the cluster. The same connection is used to serve a Web UI.

Configuration

You should use a configuration file to configure the teleport daemon. But for simpler experimentation you can use command line flags to teleport start command. To see the list of flags:

> teleport start --help

Output:

usage: teleport start [<flags>]
Flags:
  -d, --debug         Enable verbose logging to stderr
  -r, --roles         Comma-separated list of roles to start with [proxy,node,auth]
      --advertise-ip  IP to advertise to clients if running behind NAT
  -l, --listen-ip     IP address to bind to [0.0.0.0]
      --auth-server   Address of the auth server [127.0.0.1:3025]
      --token         One-time token to register with an auth server [none]
      --nodename      Name of this node, defaults to hostname
  -c, --config        Path to a configuration file [/etc/teleport.yaml]
      --labels        List of labels for this node

Configuration Flags

Let's cover some of these flags in more detail:

  • --roles flag tells Teleport which services to start. It is a comma-separated list of roles. The possible values are auth, node and proxy. The default value is auth,node,proxy. These roles are explained in the Teleport Architecture document.

  • --advertise-ip flag can be used when Teleport nodes are running behind NAT and their externally routable IP cannot be automatically determined. For example, assume that a host "foo" can be reached via 10.0.0.10 but there is no A DNS record for "foo", so you cannot connect to it via tsh ssh foo. If you start teleport on "foo" with --advertise-ip=10.0.0.10, it will automatically tell Teleport proxy to use that IP when someone tries to connect to "foo". This is also useful when connecting to Teleport nodes using their labels.

  • --nodename flag lets you assign an alternative name the node which can be used by clients to login. By default it's equal to the value returned by hostname command.

  • --listen-ip should be used to tell teleport daemon to bind to a specific network interface. By default it listens on all.

  • --labels flag allows to assign a set of labels to a node. See the explanation of labeling mechanism in "Labeling Nodes" section below.

Configuration File

Teleport uses YAML file format for configuration. A sample configuration file is shown below. By default it is stored in /etc/teleport.yaml

!!! note "IMPORTANT": When editing YAML configuration, please pay attention to how your editor handles white space. YAML requires consistent handling of tab characters.

# By default, this file should be stored in /etc/teleport.yaml

# This section of the configuration file applies to all teleport
# services.
teleport:
    # nodename allows to assign an alternative name this node can be reached by.
    # by default it's equal to hostname
    nodename: graviton

    # Data directory where Teleport keeps its data, like keys/users for 
    # authentication (if using the default BoltDB back-end)
    data_dir: /var/lib/teleport

    # one-time invitation token used to join a cluster. it is not used on 
    # subsequent starts
    auth_token: xxxx-token-xxxx

    # when running in multi-homed or NATed environments Teleport nodes need 
    # to know which IP it will be reachable at by other nodes
    advertise_ip: 10.1.0.5

    # list of auth servers in a cluster. you will have more than one auth server
    # if you configure teleport auth to run in HA configuration
    auth_servers: 
        - 10.1.0.5:3025
        - 10.1.0.6:3025

    # Teleport throttles all connections to avoid abuse. These settings allow
    # you to adjust the default limits
    connection_limits:
        max_connections: 1000
        max_users: 250

    # Logging configuration. Possible output values are 'stdout', 'stderr' and 
    # 'syslog'. Possible severity values are INFO, WARN and ERROR (default).
    log:
        output: stderr
        severity: ERROR

    # Type of storage used for keys. You need to configure this to use etcd
    # backend if you want to run Teleport in HA configuration.
    storage:
        type: bolt

# This section configures the 'auth service':
auth_service:
    enabled: yes
    # IP and the port to bind to. Other Teleport nodes will be connecting to
    # this port (AKA "Auth API" or "Cluster API") to validate client 
    # certificates 
    listen_addr: 0.0.0.0:3025

    # Pre-defined tokens for adding new nodes to a cluster. Each token specifies
    # the role a new node will be allowed to assume. The more secure way to 
    # add nodes is to use `ttl node add --ttl` command to generate auto-expiring 
    # tokens. 
    #
    # We recommend to use tools like `pwgen` to generate sufficiently random
    # tokens of 32+ byte length.
    tokens:
        - "proxy,node:xxxxx"
        - "auth:yyyy"

    # Optional "cluster name" is needed when confniguring trust between multiple
    # auth servers. A cluster name is used as part of a signature in certificates
    # generated by this CA.
    # 
    # By default an automatically generated GUID is used.
    #
    # IMPORTANT: if you change cluster_name, it will invalidate all generated 
    # certificates and keys (may need to wipe out /var/lib/teleport directory)
    cluster_name: "main"

    # List (array) of other clusters this CA trusts.
    trusted_clusters:
      - key_file: /path/to/main-cluster.ca
        # Comma-separated list of OS logins allowed to users of this 
        # trusted cluster
        allow_logins: john,root
        # Establishes a reverse SSH tunnel from this cluster to the trusted
        # cluster, allowing the trusted cluster users to access nodes of this 
        # cluster
        tunnel_addr: 80.10.0.12:3024

# This section configures the 'node service':
ssh_service:
    enabled: yes
    # IP and the port for SSH service to bind to. 
    listen_addr: 0.0.0.0:3022
    # See explanation of labels in "Labeling Nodes" section below
    labels:
        role: master
        type: postgres
    # List (YAML array) of commands to periodically execute and use
    # their output as labels. 
    # See explanation of how this works in "Labeling Nodes" section below
    commands:
    - name: hostname
      command: [/usr/bin/hostname]
      period: 1m0s
    - name: arch
      command: [/usr/bin/uname, -p]
      period: 1h0m0s

# This section configures the 'proxy servie'
proxy_service:
    enabled: yes
    # SSH forwarding/proxy address. Command line (CLI) clients always begin their
    # SSH sessions by connecting to this port
    listen_addr: 0.0.0.0:3023

    # Reverse tunnel listening address. An auth server (CA) can establish an 
    # outbound (from behind the firewall) connection to this address. 
    # This will allow users of the outside CA to connect to behind-the-firewall 
    # nodes.
    tunnel_listen_addr: 0.0.0.0:3024

    # The HTTPS listen address to serve the Web UI and also to authenticate the 
    # command line (CLI) users via password+HOTP
    web_listen_addr: 0.0.0.0:3080

    # TLS certificate for the HTTPS connection. Configuring these properly is 
    # critical for Teleport security.
    https_key_file: /etc/teleport/teleport.key
    https_cert_file: /etc/teleport/teleport.crt

Adding and Deleting Users

A user identity in Teleport exists in the scope of a cluster. The member nodes of a cluster have multiple OS users on them. A Teleport administrator assigns allowed logins to every Teleport account, allowing it to login as one of the specified OS users.

Let's look at this table:

Teleport Username Allowed Logins Description
joe joe,root Teleport user 'joe' can login into member nodes as OS user 'joe' or 'root'
bob bob Teleport user 'bob' can login into member nodes only as OS user 'bob'
ross If no login is specified, it defaults to the same name as the Teleport user.

To add a new user to Teleport you have to use tctl tool on the same node where the auth server is running, i.e. teleport was started with --roles=auth.

> tctl users add joe joe,root

Teleport generates an auto-expiring token (with a TTL of 1 hour) and prints the token URL which must be shared with a user beforeo the TTL expires.

Signup token has been created. Share this URL with the user:
https://<proxy>:3080/web/newuser/xxxxxxxxxxxx

NOTE: make sure the <proxy> host is accessible.

The user will complete registration by visiting this URL, picking a password and configuring the 2nd factor authentication. If the credentials are correct, the auth server generates and signs a new certificate and the client stores this key and will use it for subsequent logins. The key will automatically expire after 23 hours by default after which the user will need to log back in with her credentials. This TTL can be configured to a maximum of 30 hours and a minimum of 1 minute. Once authenticated, the account will become visible via tctl:

> tctl users ls

User           Allowed to Login as
----           -------------------
admin          admin,root
ross           ross
joe            joe,root

Joe would need to use the tsh client tool to login into member node "luna" via bastion "work" as root:

> tsh --proxy=work --user=joe root@luna

To delete this user:

> tctl users del joe

Controlling access

At the moment teleport does not have a command for modifying an existing user record. The only way to update allowed logins or reset the user password is to remove the account and re-create it.

The user will have to re-initialize Google Authenticator on their phone.

Adding Nodes to the Cluster

Gravitational Teleport is a "clustered" SSH manager, meaning it only allows SSH access to nodes that had been previously granted cluster membership.

A cluster membership means that every node in a cluster has its own host certificate signed by the cluster's auth server.

A new Teleport node needs an "invite token" to join a cluster. An invitation token also defines which role a new node can assume within a cluster: auth, proxy or node.

There are two ways to create invitation tokens:

  • Static Tokens
  • Short-lived Tokens

Static Tokens

You can pick your own tokens and add them to the auth server's config file:

# Config section in `/etc/teleport/teleport.yaml` file for the auth server
auth_service:
    enabled: true
    #
    # statically assigned token: obviously we recommend a much harder to guess
    # value than `xxxxx`, consider generating tokens using a tool like pwgen
    #
    tokens:
    - "proxy,node:xxxxxx"

Now you can start a new Teleport node by setting its invitation token via --token flag to "xxxxxx". This node will join the cluster as a regular node but also as a proxy server:

teleport start --roles=node,auth --token=xxxxx --auth-server=10.0.10.5

Short-lived Tokens

A more secure way to add nodes to a cluster is to generate tokens as they are needed. Such token can be used multiple times until its time to live (TTL) expires.

Use tctl tool to invite a new node into the cluster with node and auth roles:

tctl nodes --ttl=5m --roles=node,proxy add

As new nodes come online, they start sending ping requests every few seconds to the CA of the cluster. This allows everyone to explore cluster membership and size:

> tctl nodes ls

Node Name     Node ID                                  Address            Labels
---------     -------                                  -------            ------
turing        d52527f9-b260-41d0-bb5a-e23b0cfe0f8f     10.1.0.5:3022      distro:ubuntu
dijkstra      c9s93fd9-3333-91d3-9999-c9s93fd98f43     10.1.0.6:3022      distro:debian

Revoking Invitations

As you have seen above, Teleport uses tokens to invite users to a cluster (sign-up tokens) or to add new nodes to it (provisioning tokens).

Both types of tokens can be revoked before they can be used. To see a list of outstanding tokens, run this command:

> tctl tokens ls

Token                                Role       Expiry Time (UTC)
-----                                ----       -----------------
eoKoh0caiw6weoGupahgh6Wuo7jaTee2     Proxy      never
696c0471453e75882ff70a761c1a8bfa     Node       17 May 16 03:51 UTC
6fc5545ab78c2ea978caabef9dbd08a5     Signup     17 May 16 04:24 UTC

In this example, the first token with "never" expiry date is a static token configured via a config file. It cannot be revoked.

The 2nd token with "Node" role was generated to invite a new node to this cluster. And the 3rd token was generated to invite a new user.

The latter two tokens can be deleted (revoked) via tctl tokens del command:

> tctl tokens del 696c0471453e75882ff70a761c1a8bfa
Token 696c0471453e75882ff70a761c1a8bfa has been deleted

Labeling Nodes

In addition to specifying a custom nodename, Teleport also allows to apply arbitrary key:value pairs to each node. They are called labels. There are two kinds of labels:

  1. static labels never change while the teleport process is running. You may want to label nodes with their physical location, the Linux distribution, etc.

  2. label commands or "dynamic labels". Label commands allow you to execute an external command on a node at a configurable frequency. The output of that command becomes the value of such label. Examples include reporting a kernel version, load averages, time after reboot, etc.

Labels can be configured in a configuration file or via --labels flag as shown below:

> teleport start --labels uptime=[1m:"uptime -p"],kernel=[1h:"uname -r"]

Obviously the kernel version is not going to change often, so this example runs uname once an hour. When this node starts and reports its labels into the cluster, users will see:

> tctl nodes ls

Node Name     Node ID          Address         Labels
---------     -------          -------         ------
turing        d52527f9-b260    10.1.0.5:3022   kernel=3.19.0-56,uptime=up 1 hour, 15 minutes

Trusted Clusters

Teleport allows to partition your infrastructure into multiple clusters. Some clusters can be located behind firewalls without any open ports. They can also have their own restrictions on which users have the access.

As explained above, a Teleport Cluster has a name and is managed by a teleport daemon with "auth service" enabled.

How does it work?

Let's assume we need to place some servers behind a firewall and we only want Teleport user "john" to have access to them. We already have our primary Teleport cluster and our users set up. Say this primary cluster is called main, and behind-the-firewall cluster is called cluster-b as shown on this diagram:

Tunels

This setup works as follows:

  1. cluster-b and main trust each other: they are "trusted clusters".
  2. cluster-b creates an outbound reverse SSH tunnel to main and keeps it open.
  3. Users of main should use --cluster=cluster-b flag of tsh tool if they want to connect to any nodes of cluster-b.
  4. The main cluster uses the tunnel to connect back to any node of cluster-b.

Example Configuration

To add behind-the-firewall machines and restrict access only to "john", we will have to do the following:

  1. Add cluster-b to the list of trusted clusters of main.
  2. Add main cluster to the list of trusted clusters of cluster-b.
  3. Tell cluster-b to open a reverse tunnel to main.
  4. Tell cluster-b to only allow user "john" from the main cluster.

Let's look into the details of each step. First, let's configure two independent (at first) clusters:

auth_service:
  enabled: yes
  cluster_name: main

And our behind-the-firewall cluster:

auth_service:
  enabled: yes
  cluster_name: cluster-b

Start both servers. At this point they do not know about each other. Now, export their public CA keys:

On "main":

> tctl auth export > main-cluster.ca

On "cluster-b":

> tctl auth export > b-cluster.ca

Update the YAML configuration of both clusters to connect them. On main:

auth_service:
  enabled: yes
  cluster_name: main
  trusted_clusters:
      - key_file: /path/to/b-cluster.ca

... and on cluster-b, notice the tunnel_addr - that should point to the address of main proxy node:

auth_service:
  enabled: yes
  cluster_name: cluster-b
  trusted_clusters:
      - key_file: /path/to/main-cluster.ca
        # This line contains comma-separated list of OS logins allowed
        # to users from this trusted cluster
        allow_logins: john
        # This line establishes a reverse SSH tunnel from 
        # cluster-b to main:
        tunnel_addr: 62.28.10.1

Now, if you restart teleport auth service on both clusters, they should trust each other. To verify, run this on "cluster-b":

> tctl auth ls
CA keys for the local cluster cluster-b:

CA Type     Fingerprint
-------     -----------
user        xxxxxxxxxxxxxxx
host        zzzzzzzzzzzzzzz

CA Keys for Trusted Clusters:

Cluster Name     CA Type     Fingerprint                     Allowed Logins
------------     -------     -----------                     --------------
main             user        zzzzzzzzzzzzzzzzzzzzzzzzzzz     john
main             host        xxxxxxxxxxxxxxxxxxxxxxxxxxx     N/A

Notice that each cluster is shown as two CAs: one is used to establish trust between nodes, and another one is for trusting users.

Now, John, having direct access to a proxy server of cluster "main" (let's call it main.proxy) can use tsh command to see which clusters are online:

> tsh --proxy=main.proxy clusters

John can also list all nodes in the cluster-b:

> tsh --proxy=main.proxy --cluster=cluster-b ls

Similarly, by passing --cluster=cluster-b to tsh John can login into cluster-b nodes.

Using Teleport with OpenSSH

Teleport is a fully standards-compliant SSH proxy and it can work in environments with existing SSH implementations, such as OpenSSH. This section will cover:

  • Configuring OpenSSH client ssh to login into nodes inside a Teleport cluster.
  • Configuring OpenSSH server sshd to join a Teleport cluster.

Using OpenSSH Client

It is possible to use OpenSSH client ssh to connect to Teleport clusters. A Teleport proxy works by using the standard SSH proxy subsystem. This section will explain how to configure OpenSSH client to use it.

First, you need to export the public keys of cluster members. This has to be done on a node which runs Teleport auth server and probably must be done by a Teleport administrator:

> tctl auth --type=host export > cluster_node_keys

On your client machine, you need to import these keys. It will allow your OpenSSH client to verify that host's certificates are signed by the trusted CA key:

> cat cluster_node_keys >> ~/.ssh/known_hosts

Configure OpenSSH client to use the Teleport proxy when connecting to nodes with matching names. Edit /etc/ssh/ssh_config:

# Tell OpenSSH client to use work.example.com as a jumphost (proxy) when logging
# to any remote node whose name matches the pattern *.work.example.com
# Beware of recursion here (when proxy name matches your pattern)
Host *.work.example.com
  ProxyCommand ssh -p 3023 %[email protected] -s proxy:%h:%p

Launch tsh in the SSH agent mode:

> tsh --proxy=work.example.com agent

tsh agent will print environment variables into the console. Configure your system to evaluate these variables: they tell ssh to use tsh to authenticate you against work.example.com cluster.

When everything is configured properly, you can use ssh to connect to any node behind work.example.com:

> ssh [email protected]

Integrating with OpenSSH Servers

Existing sshd servers can be added to a Teleport cluster. For that to work, you have to configure sshd to trust Teleport CA.

Export the Teleport CA certificate into a file:

> tctl auth --type=user export > cluster-ca.pub

Copy this file to every node running sshd, for example into /etc/ssh/teleport-ca.pub Then update the sshd configuration, usually /etc/ssh/sshd_config:

TrustedUserCAKeys /etc/ssh/user-ca.pub

Integrating with Ansible

Ansible is using OpenSSH client by default, this makes it compatible with Teleport without any extra work except configuring OpenSSH client to work with Teleport Proxy:

  • configure your OpenSSH to connect to Teleport proxy and user tsh agent socket
  • enable scp mode in the Ansible config file (default is /etc/ansible/ansible.cfg):
scp_if_ssh = True

OpenID / OAuth2

Teleport supports OpenID Connect (also known as OIDC) to provide external authentication using OpenID providers like Google Apps.

Using OpenID Connect / OAuth2 with Google Apps

First, you must configure OpenID Connect credentials via Google's Developers Center. Please refer to this guide to configure an OIDC integration with applications like Teleport.

  • Create Teleport Project that will identify your installation:

Create project

  • Set up consent screen:

Create project

  • Create "Web application" client ID:

Client ID

  • Get OAuth 2.0 client credentials:

Client Creds

  • Add OIDC connector to teleport config:
auth_service:
  enabled: true
  cluster_name: magadan
  oidc_connectors:    
    - id: google
      redirect_url: https://localhost:3080/v1/webapi/oidc/callback
      client_id: id-from-google.apps.googleusercontent.com
      client_secret: secret-key-from-google
      issuer_url: https://accounts.google.com

Now you should be able to create Teleport users whose identity is managed by Google. Assuming your company domain is example.com and it's hosted on Google Apps, let's create a new Teleport user "sasha" with an email address [email protected] and allow him to login as root to Teleport nodes:

tctl users add sasha root,sasha --identity google:[email protected]

Logging in via OpenID Connect

Web UI

Now, if everything is set up correctly, you will see "Login with Google" button on the login screen:

OIDC Login

CLI

You have to tell tsh to authenticate via Google by providing an --auth flag:

tsh --proxy <proxy-addr> ssh --auth=google <server-addr>

You should get a browser open a login window for you, where you will have to enter your Google credentials. Teleport will keep you logged in for the next 23 hours.

!!! tip "Other Providers?": We have already received the requests to add support for other OpenID/OAuth2 providers like Github. Teleport is an open source project and adding providers is not hard, your contributions are welcome, just search the code for OIDC! :-)

High Availability and Clustering

Teleport can use etcd as a storage backend to achieve highly available deployments. Obviously, you must take steps to protect access to etcd in this configuration, because that is where Teleport secrets like keys and user records will be stored.

To configure Teleport for using etcd backend:

  • Install etcd and configure peer and client TLS authentication using etcd security guide.

  • Confnigure Teleport auth server to use etcd in the "storage" section of the config file:

teleport:
    storage:
        type: etcd
        # still need data dir for local storage purposes
        data_dir: /var/lib/teleport
        # list of etcd peers to connect to
        peers:
        - https://172.17.0.1:4001
        # required path to TLS client certificate file to connect to etcd
        tls_cert_file: /var/lib/teleport/etcd-cert.pem
        # required path to TLS private key file to connect to etc
        tls_key_file: /var/lib/teleport/etcd-key.pem
        # optional file with trusted CA authority
        # file to authenticate etcd nodes
        tls_ca_file: /var/lib/teleport/etcd-ca.pem
  • Deploy several Auth servers connected to etcd backend.
  • Deploy several Proxy nodes that have auth_servers pointed to list of Auth servers to connect.

!!! tip "NOTE": As new Auth servers will be added to the cluster and old servers will be decommissioned, node's and proxies will refresh the list of available auth servers refresh the cluster info and store the updated list locally in /var/lib/teleport/authservers.json. The values from this file, if present, will take precedence over configuration file's values. You can simply remove the file so that the configuration file's values can take effect again.

DynamoDB back-end

Teleport also supports community-supplied DynamoDB support for storing secrets. You need to compile Teleport with DynamoDB build tags. See DynamoDB plugin documentation for more details.

Troubleshooting

To diagnose problems you can configure teleport to run with verbose logging enabled.

!!! tip "NOTE": It is not recommended to run Teleport in production with verbose logging as it generates substantial amount of data.

Sometimes you may want to reset teleport to a clean state. This can be accomplished by erasing everything under "data_dir" directory. Assuming the default location, rm -rf /var/lib/teleport/* will do.

Getting Help

Please open an issue on Github. Alternatively, you can reach through the contact form on our website.

For commercial support, custom features or to try our multi-cluster edition of Teleport, please reach out to us: [email protected].