GaussDB(DWS) supports the standard SSL. As a highly secure protocol, SSL authenticates bidirectional identification between the server and client using digital signatures and digital certificates to ensure secure data transmission. To support SSL connection, GaussDB(DWS) has obtained the formal certificates and keys for the server and client from the CA certification center. It is assumed that the key and certificate for the server are server.key and server.crt respectively; the key and certificate for the client are client.key and client.crt respectively, and the name of the CA root certificate is cacert.pem.

The SSL connection mode is more secure. By default, the SSL feature in a cluster allows SSL and non-SSL connections from the client. For security purposes, you are advised to connect to the cluster via SSL from the client. Ensure the certificate, private key, and root certificate of the GaussDB(DWS) server have been configured by default. To forcibly use an SSL connection, configure the require_ssl parameter in the Require SSL Connection area of the cluster's Security Settings page on the GaussDB(DWS) management console. Require SSL Connection on the Security Settings page of the cluster. For more information, see Configuring SSL Connection and Combinations of SSL Connection Parameters on the Client and Server.

The client or JDBC/ODBC driver needs to use SSL connection. Configure related SSL connection parameters in the client or application code. The GaussDB(DWS) console provides the SSL certificate required by the client. The SSL certificate contains the default certificate, private key, root certificate, and private key password encryption file required by the client. Download the SSL certificate to the host where the client is installed, and specify the path of the certificate on the client. For more information, see Configuring Digital Certificate Parameters Related to SSL Authentication on the gsql Client and SSL Authentication Modes and Client Parameters.

Using the default certificate may pose security risks. To improve system security, you are advised to periodically change the certificate to prevent password cracking. If you need to replace the certificate, contact the database customer service.

Configuring SSL Connection

Prerequisites

Changes made to security configuration parameters require a cluster restart to take effect. Otherwise, the cluster will be temporarily unavailable.

To modify the cluster's security configuration, ensure that the following conditions are met:
- The cluster status is Available or Unbalanced.
- The Task Information cannot be set to Creating snapshot, Scaling out, Configuring, or Restarting.

Procedure

Log in to the GaussDB(DWS) console.
In the navigation pane on the left, choose Clusters > Dedicated Clusters.
In the cluster list, click the name of a cluster. On the page that is displayed, click Security Settings.
By default, Configuration Status is Synchronized, which indicates that the latest database result is displayed.
In the SSL Connection area, enable Require SSL Connection (recommended).
indicates the function is enabled. The require_ssl is set to 1, indicating that the server forcibly requires the SSL connection.

indicates the function is disabled (default value). The require_ssl parameter is set to 0, indicating that the server does not require SSL connections. For details about how to configure the require_ssl parameter, see require_ssl (Server).
- If the gsql client or ODBC driver provided by GaussDB(DWS) is used, GaussDB(DWS) supports the TLSv1.2 SSL protocol.
- If the JDBC driver provided by GaussDB(DWS) is used, GaussDB(DWS) supports SSL protocols, such as SSLv3, TLSv1, TLSv1.1, and TLSv1.2. The SSL protocol used between the client and the database depends on the Java Development Kit (JDK) version used by the client. Generally, JDK supports multiple SSL protocols.
Click Apply.
The system automatically saves the SSL connection settings. On the Security Settings page, Configuration Status is Applying. After Configuration Status changes to Synchronized, the settings have been saved and taken effect.

Configuring Digital Certificate Parameters Related to SSL Authentication on the gsql Client

After a data warehouse cluster is deployed, the SSL authentication mode is enabled by default. The server certificate, private key, and root certificate have been configured by default. You need to configure the client parameters.

Log in to the GaussDB(DWS) console. In the navigation pane, choose Client Connections.
In the Driver area, click download an SSL certificate.
Use a file transfer tool (such as WinSCP) to upload the SSL certificate to the host where the client is installed.
For example, save the downloaded certificate dws_ssl_cert.zip to the /home/dbadmin/dws_ssl/ directory.
Use an SSH remote connection tool (such as PuTTY) to log in to the host where the gsql client is installed and run the following commands to go to the directory where the SSL certificate is stored and decompress the SSL certificate:
```
cd /home/dbadmin/dws_ssl/
unzip dws_ssl_cert.zip
```
Run the export command and configure digital certificate parameters related to SSL authentication on the host where the gsql client is installed.
There are two SSL authentication modes: bidirectional authentication and unidirectional authentication. The client environment variables to be configured vary according to the authentication mode. For details, see SSL Authentication Modes and Client Parameters.

The following parameters must be configured for bidirectional authentication:
```
export PGSSLCERT="/home/dbadmin/dws_ssl/sslcert/client.crt"
export PGSSLKEY="/home/dbadmin/dws_ssl/sslcert/client.key"
export PGSSLMODE="verify-ca"
export PGSSLROOTCERT="/home/dbadmin/dws_ssl/sslcert/cacert.pem"
```
The following parameters must be configured for unidirectional authentication:
```
export PGSSLMODE="verify-ca"
export PGSSLROOTCERT="/home/dbadmin/dws_ssl/sslcert/cacert.pem"
```
- You are advised to use bidirectional authentication for security purposes.
- The environment variables configured for a client must contain the absolute file paths.
Change the client private key permissions.
The permissions on the client's root certificate, private key, certificate, and encrypted private key file must be 600. If the permissions do not meet the requirement, the client cannot connect to the cluster in SSL mode.
```
chmod 600 client.key
chmod 600 client.crt
chmod 600 client.key.cipher
chmod 600 client.key.rand
chmod 600 cacert.pem
```

SSL Authentication Modes and Client Parameters

There are two SSL authentication modes: bidirectional authentication and unidirectional authentication. Table Table 1 shows the differences between these two modes. You are advised to use bidirectional authentication for security purposes.

**Table 1** Authentication modes
Authentication Mode	Description	Environment Variables Configured on a Client	Maintenance
Bidirectional authentication (recommended)	The client verifies the server's certificate and the server verifies the client's certificate. The connection can be set up only after the verifications are successful.	Set the following environment variables: PGSSLCERT PGSSLKEY PGSSLROOTCERT PGSSLMODE	This authentication mode is applicable to scenarios that require high data security. When using this mode, you are advised to set the PGSSLMODE client variable to verify-ca for network data security purposes.
Unidirectional authentication	The client verifies the server's certificate, whereas the server does not verify the client's certificate. The server loads the certificate information and sends it to the client. The client verifies the server's certificate according to the root certificate.	Set the following environment variables: PGSSLROOTCERT PGSSLMODE	To prevent TCP-based security attacks, you are advised to use the SSL certificate authentication. In addition to configuring the client root certificate, you are advised to set the PGSSLMODE variable to verify-ca on the client.

Configure environment variables related to SSL authentication on the client. For details, see Table 2.

The path of environment variables is set to /home/dbadmin/dws_ssl/ as an example. Replace it with the actual path.

**Table 2** Client parameters
Environment Variable	Description	Value Description
PGSSLCERT	Specifies the certificate files for a client, including the public key. Certificates prove the legal identity of the client and the public key is sent to the remote end for data encryption.	The absolute path of the files must be specified, for example: export PGSSLCERT='/home/dbadmin/dws_ssl/sslcert/client.crt' (No default value)
PGSSLKEY	Specifies the client private key file used to decrypt the digital signatures and the data encrypted using the public key.	The absolute path of the files must be specified, for example: export PGSSLKEY='/home/dbadmin/dws_ssl/sslcert/client.key' (No default value)
PGSSLMODE	Specifies whether to negotiate with the server about SSL connection and specifies the priority of the SSL connection.	Values and meanings: disable: only tries to establish a non-SSL connection. allow: tries to establish a non-SSL connection first, and then an SSL connection if the first attempt fails. prefer: tries to establish an SSL connection first, and then a non-SSL connection if the first attempt fails. require: only tries to establish an SSL connection. If there is a CA file, perform the verification according to the scenario in which the parameter is set to verify-ca. verify-ca: tries to establish an SSL connection and check whether the server certificate is issued by a trusted CA. verify-full: GaussDB(DWS) does not support this mode. Default value: prefer NOTE: When an external client accesses a cluster, the error message "ssl SYSCALL error" is displayed on some nodes. In this case, run export PGSSLMODE="allow" or export PGSSLMODE="prefer".
PGSSLROOTCERT	Specifies the root certificate file for issuing client certificates. The root certificate is used to verify the server certificate.	The absolute path of the files must be specified, for example: export PGSSLROOTCERT='/home/dbadmin/dws_ssl/sslcert/certca.pem' Default value: null
PGSSLCRL	Specifies the certificate revocation list file, which is used to check whether a server certificate is in the list. If the certificate is in the list, it is invalid.	The absolute path of the files must be specified, for example: export PGSSLCRL='/home/dbadmin/dws_ssl/sslcert/sslcrl-file.crl' Default value: null

Combinations of SSL Connection Parameters on the Client and Server

Whether the client uses the SSL encryption connection mode and whether to verify the server certificate depend on client parameter sslmode and server (cluster) parameters ssl and require_ssl. The parameters are as follows:

ssl (Server)
The ssl parameter indicates whether to enable the SSL function. on indicates that the function is enabled, and off indicates that the function is disabled.
- The default value is on for clusters whose version is 1.3.1 or later, and you cannot set this parameter on the GaussDB(DWS) console.
- For clusters whose version is earlier than 1.3.1, the default value is on. You can set this parameter in the SSL Connection area on the cluster's Security Settings page of the GaussDB(DWS) console.
require_ssl (Server)
The require_ssl parameter specifies whether the server forcibly requires SSL connection. This parameter is valid only when ssl is set to on. on indicates that the server forcibly requires SSL connection. off indicates that the server does not require SSL connection.
- The default value is off for clusters whose version is 1.3.1 or later. You can set the require_ssl parameter in the Require SSL Connection area of the cluster's Security Settings page on the GaussDB(DWS) console.
- For clusters whose version is earlier than 1.3.1, the default value is off, and you cannot set this parameter on the GaussDB(DWS) console.
sslmode (Client)
You can set this parameter in the SQL client tool.
- In the gsql command line client, this parameter is the PGSSLMODE parameter.
- On the Data Studio client, this parameter is the SSL Mode parameter.

The combinations of client parameter sslmode and server parameters ssl and require_ssl are as follows.

**Table 3** Combinations of SSL connection parameters on the client and server
ssl (Server)	sslmode (Client)	require_ssl (Server)	Result
on	disable	on	The server requires SSL, but the client disables SSL for the connection. As a result, the connection cannot be set up.
	disable	off	The connection is not encrypted.
	allow	on	The connection is encrypted.
	allow	off	The connection is not encrypted.
	prefer	on	The connection is encrypted.
	prefer	off	The connection is encrypted.
	require	on	The connection is encrypted.
	require	off	The connection is encrypted.
	verify-ca	on	The connection is encrypted and the server certificate is verified.
	verify-ca	off	The connection is encrypted and the server certificate is verified.
off	disable	on	The connection is not encrypted.
	disable	off	The connection is not encrypted.
	allow	on	The connection is not encrypted.
	allow	off	The connection is not encrypted.
	prefer	on	The connection is not encrypted.
	prefer	off	The connection is not encrypted.
	require	on	The client requires SSL, but SSL is disabled on the server. Therefore, the connection cannot be set up.
	require	off	The client requires SSL, but SSL is disabled on the server. Therefore, the connection cannot be set up.
	verify-ca	on	The client requires SSL, but SSL is disabled on the server. Therefore, the connection cannot be set up.
	verify-ca	off	The client requires SSL, but SSL is disabled on the server. Therefore, the connection cannot be set up.

Establishing Secure TCP/IP Connections in SSL Mode

Configuring SSL Connection

Configuring Digital Certificate Parameters Related to SSL Authentication on the gsql Client

SSL Authentication Modes and Client Parameters

Combinations of SSL Connection Parameters on the Client and Server