Materialize/doc/user/layouts/shortcodes/network-security/ssh-tunnel.md

Materialize can connect to a Kafka broker, a Confluent Schema Registry server, a PostgreSQL database, or a MySQL database through an SSH tunnel connection. In this guide, you will create an SSH tunnel connection, configure your Materialize authentication settings, and create a source connection.

Before you begin

Before you begin, make sure you have access to a bastion host. You will need:

• The bastion host IP address and port number
• The bastion host username

Create an SSH tunnel connection

In Materialize, create an SSH tunnel connection to the bastion host:

CREATE CONNECTION ssh_connection TO SSH TUNNEL (
    HOST '<SSH_BASTION_HOST>',
    USER '<SSH_BASTION_USER>',
    PORT <SSH_BASTION_PORT>
);

Configure the SSH bastion host

The bastion host needs a public key to connect to the Materialize tunnel you created in the previous step.

1. Materialize stores public keys for SSH tunnels in the system catalog. Query mz_ssh_tunnel_connections to retrieve the public keys for the SSH tunnel connection you just created:

   SELECT
       mz_connections.name,
       mz_ssh_tunnel_connections.*
   FROM
       mz_connections JOIN
       mz_ssh_tunnel_connections USING(id)
   WHERE
       mz_connections.name = 'ssh_connection';
   

   | id    | public_key_1                          | public_key_2                          |
   |-------|---------------------------------------|---------------------------------------|
   | u75   | ssh-ed25519 AAAA...76RH materialize   | ssh-ed25519 AAAA...hLYV materialize   |
   

   Materialize provides two public keys to allow you to rotate keys without connection downtime. Review the ALTER CONNECTION documentation for more information on how to rotate your keys.

2. Log in to your SSH bastion server and add each key to the bastion authorized_keys file:

   # Command for Linux
   echo "ssh-ed25519 AAAA...76RH materialize" >> ~/.ssh/authorized_keys
   echo "ssh-ed25519 AAAA...hLYV materialize" >> ~/.ssh/authorized_keys
   

3. Configure your internal firewall to allow the SSH bastion host to connect to your Kafka cluster or PostgreSQL instance.

   If you are using a cloud provider like AWS or GCP, update the security group or firewall rules for your PostgreSQL instance or Kafka brokers.

   Allow incoming traffic from the SSH bastion host IP address on the necessary ports.

   For example, use port 5432 for PostgreSQL and ports 9092, 9094, and 9096 for Kafka.

   Test the connection from the bastion host to the Kafka cluster or PostgreSQL instance.

   telnet <KAFKA_BROKER_HOST> <KAFKA_BROKER_PORT>
   telnet <POSTGRES_HOST> <POSTGRES_PORT>
   

   If the command hangs, double-check your security group and firewall settings. If the connection is successful, you can proceed to the next step.

4. Verify the SSH tunnel connection from your source to your bastion host:

   # Command for Linux
   ssh -L 9092:kafka-broker:9092 <SSH_BASTION_USER>@<SSH_BASTION_HOST>
   

   Verify that you can connect to the Kafka broker or PostgreSQL instance via the SSH tunnel:

   telnet localhost 9092
   

   If you are unable to connect using the telnet command, enable AllowTcpForwarding and PermitTunnel on your bastion host SSH configuration file.

   On your SSH bastion host, open the SSH config file (usually located at /etc/ssh/sshd_config) using a text editor:

   sudo nano /etc/ssh/sshd_config
   

   Add or uncomment the following lines:

   AllowTcpForwarding yes
   PermitTunnel yes
   

   Save the changes and restart the SSH service:

   sudo systemctl restart sshd
   

5. Retrieve the static egress IPs from Materialize and configure the firewall rules (e.g. AWS Security Groups) for your bastion host to allow SSH traffic for those IP addresses only.

   SELECT * FROM mz_catalog.mz_egress_ips;
   

   XXX.140.90.33
   XXX.198.159.213
   XXX.100.27.23
   

Validate the SSH tunnel connection

To confirm that the SSH tunnel connection is correctly configured, use the VALIDATE CONNECTION command:

VALIDATE CONNECTION ssh_connection;

If no validation errors are returned, the connection can be used to create a source connection.