Securing TCP based services

The following guide demonstrates how to use Pomerium's TCP Proxying support with various TCP services such as databases and other non-HTTP protocols. It also covers integration points with them when possible.

The source files from this guide can be found on GitHub.

Background

When replacing a traditional VPN, there are often non-HTTP based applications which must still be reachable. Pomerium is able to provide the same type of protection to these services by using a client side application to proxy TCP connections. Authentication and authorization configuration is shared with standard HTTP routes, and the underlying transport is still encrypted between the end-user and Pomerium.

Important notes:

• Pomerium authorizes HTTP on a request-by-request basis, but TCP is authorized on a per-connection basis.
• Pomerium is only authorizing the TCP connection. It does not interact with application level authorization systems at this time.

How it works

• Create a standard Pomerium configuration for your identity provider (IdP)
• pomerium-cli runs on your workstation, listening on loopback for TCP connections
• When an inbound connection is made, pomerium-cli proxies the connection through pomerium, authenticating the user if needed
• Pomerium authorizes the connection and forwards it to the upstream service
• The connecting application functions as normal

Pre-requisites

This recipe is designed to run on a local docker-compose instance. The included configuration can be adopted for any TCP service, however.

• docker
• docker-compose
• A copy of the example repo checked out
• Valid credentials for your OIDC provider
• The Pomerium Client installed
• (Optional) mkcert to generate locally trusted certificates

Certificates (optional)

This demo comes with its own certificates, but pomerium-cli and your browser will not trust them by default. You may instead provide your own or use mkcert to generate locally trusted certificates.

After installing mkcert, run the following inside the example repo:

mkcert -install
   mkcert '*.localhost.pomerium.io'

This will install a trusted CA and generate a new wildcard certificate:

• _wildcard.localhost.pomerium.io.pem
• _wildcard.localhost.pomerium.io-key.pem

To provide your own certificates through another mechanism, please overwrite these files or update docker-compose.yaml accordingly.

Configure

Pomerium

Update config.yaml with your IdP settings and desired policy if adopting for your environment

config.yaml

authenticate_service_url: https://authenticate.localhost.pomerium.io
certificates:
  - cert: /pomerium/cert.pem
    key: /pomerium/key.pem
shared_secret: CHANGEME
cookie_secret: CHANGEME
idp_client_id: CHANGEME
idp_client_secret: CHANGEME
idp_provider: google
routes:
  - from: tcp+https://redis.localhost.pomerium.io:6379
    to: tcp://redis:6379
    policy:
      - allow:
          or:
            - domain:
                is: gmail.com

  - from: tcp+https://ssh.localhost.pomerium.io:22
    to: tcp://ssh:2222
    policy:
      - allow:
          or:
            - domain:
                is: gmail.com

  - from: tcp+https://pgsql.localhost.pomerium.io:5432
    to: tcp://pgsql:5432
    policy:
      - allow:
          or:
            - domain:
                is: gmail.com

databroker_storage_type: redis
databroker_storage_connection_string: redis://redis:6379

Docker Compose

Create a docker-compose.yaml file to run Pomerium and, optionally, the services being demonstrated.

Included in our compose file:

• SSH
• Postgres
• Redis

docker-compose.md

version: "3"
services:
  pomerium:
    image: pomerium/pomerium:main
    volumes:
      - ./_wildcard.localhost.pomerium.io.pem:/pomerium/cert.pem:ro
      - ./_wildcard.localhost.pomerium.io-key.pem:/pomerium/key.pem:ro
      - ./config.yaml:/pomerium/config.yaml:ro
    ports:
      - 443:443

  redis:
    image: redis:latest
    expose:
      - 6379

  ssh:
    image: linuxserver/openssh-server:latest
    expose:
      - 2222
    environment:
      PASSWORD_ACCESS: "true"
      USER_PASSWORD: supersecret
      USER_NAME: myuser

  pgsql:
    image: postgres
    restart: always
    environment:
      POSTGRES_PASSWORD: supersecret
    expose:
      - 5432

Connect

To connect to your service, ensure pomerium-cli is in your $PATH and run the tcp command, specifying the service you wish to reach.

pomerium-cli tcp [hostname]:[port]

pomerium-cli will select a random port on localhost by default, but you can specify a port manually if desired. Keep reading for some specific application examples using the sample docker-compose.yaml.

Redis

# Start a proxy to redis in the background
pomerium-cli tcp redis.localhost.pomerium.io:6379 --listen localhost:6379 &
3:01PM INF tcptunnel: listening on 127.0.0.1:6379

# Start the redis client
redis-cli
3:01PM INF tcptunnel: opening connection dst=redis.localhost.pomerium.io:6379 proxy=redis.localhost.pomerium.io:443 secure=true
3:01PM INF tcptunnel: opening connection dst=redis.localhost.pomerium.io:6379 proxy=redis.localhost.pomerium.io:443 secure=true
3:01PM INF tcptunnel: connection established
127.0.0.1:6379> keys *
 1) "type.googleapis.com/session.Session_last_version"
 2) "type.googleapis.com/user.User"
 3) "type.googleapis.com/session.Session"
 4) "type.googleapis.com/user.User_version_set"
 5) "type.googleapis.com/user.User_last_version"
 6) "server_version_last_version"
 7) "type.googleapis.com/session.Session_version_set"
 8) "server_version_version_set"
 9) "server_version"
10) "type.googleapis.com/directory.User_last_version"```

Postgres

In our example docker-compose, we have configured supersecret as the password for the postgres user.

# Start a proxy to postgres in the background
pomerium-cli tcp pgsql.localhost.pomerium.io:5432 --listen localhost:5432 &
3:07PM INF tcptunnel: listening on 127.0.0.1:5432

# Connect and list the schemas after password authentication
psql -h localhost -W -U postgres -c '\dn'
Password:
3:06PM INF tcptunnel: opening connection dst=pgsql.localhost.pomerium.io:5432 proxy=pgsql.localhost.pomerium.io:443 secure=true
3:06PM INF tcptunnel: connection established
  List of schemas
  Name  |  Owner
--------+----------
 public | postgres
(1 row)

SSH

SSH clients can make use of external programs to establish a connection to a host. Most frequently, this is for using an SSH jump host to reach a target system. However, any transport application can be used. pomerium-cli's tcp command can be used in conjunction with this configuration. Read on to see how.

More Info:

• https://man.openbsd.org/ssh_config.5#ProxyCommand
• https://www.redhat.com/sysadmin/ssh-proxy-bastion-proxyjump

Setup

To configure your SSH client to use Pomerium's TCP support for SSH routes, create an entry as follows in your ssh_config or ~/.ssh/config:

Host *.localhost.pomerium.io
    ProxyCommand pomerium-cli tcp --listen - %h:%p

• Be sure to substitute your domain for localhost.pomerium.io
• Be sure pomerium-cli is in your $PATH

Connecting

That's it! A Pomerium proxy will be started automatically whenever you ssh to a host under localhost.pomerium.io.

In our example docker-compose, we have an SSH server configured with supersecret as the password for myuser.

ssh myuser@ssh.localhost.pomerium.io
3:19PM INF tcptunnel: opening connection dst=ssh.localhost.pomerium.io:22 proxy=ssh.localhost.pomerium.io:443 secure=true
3:19PM INF tcptunnel: connection established
myuser@ssh.localhost.pomerium.io's password:
Welcome to OpenSSH Server

5c9f4fa5f5f7:~$