ApsaraDB for Redis:Why do on-premises devices fail to connect to ApsaraDB for Redis over the Internet?

Step 1: Check whether the error message is invalid password, WRONGPASS, or NOAUTH Authentication required

If the error message is connection timed out or no explicit error message is displayed, skip Step 1 and proceed to Step 2.

Error description

If the error message is invalid password, WRONGPASS invalid username-password pair, or NOAUTH Authentication required, the account and password are incorrect.

Solution

• Use a password in the <user>:<password> format to re-establish the connection. For example, if the username of a custom account is testaccount and the password is Rp829dlwa, enter testaccount:Rp829dlwa as the password.

• If a password error is still reported when you use a password in the <user>:<password> format to reconnect the on-premises device to the ApsaraDB for Redis instance, you may have entered a wrong password. In this case, reset the password and use the new password to re-establish the connection. For more information about how to reset the password, see Change or reset the password.

Step 2: Run the ping command to check whether the on-premises device is connected to the ApsaraDB for Redis instance

Procedure

Run the ping command on the on-premises device.

ping <host>

Example: ping r-bp1zx****.redis.rds.aliyuncs.com

Result description

• If the ping operation is successful, the network is connected, as shown in the following figure. You can proceed to Step 3 for further troubleshooting.

  Result illustrations

  Linux

  In Linux, the system continuously sends ping requests after the ping command is run. You can press Ctrl+C to stop the execution and collect statistics, as shown in the following figure.

  

  Windows

  In Windows, the system returns the test result after the ping command is run four times, as shown in the following figure.

  

• If a message similar to 0 packets received,100.0% packet loss is returned, the network is not connected.

  Check whether the endpoint that you use is the public endpoint of the instance.

• If a message similar to Unknown host or Name or service not known is returned, an error occurs during address resolution.

  Check whether the endpoint that you use has spelling mistakes.

Common causes

• A Virtual Private Cloud (VPC) endpoint is used to connect to the ApsaraDB for Redis instance.

  To connect an on-premises device to an ApsaraDB for Redis instance, you must use a public endpoint.

• The endpoint has spelling mistakes.

  The IP address cannot be resolved because the endpoint is misspelled or the domain name fails to be resolved.

Solution

1. In the Connection Information section of the Instance Information page in the ApsaraDB for Redis console, view the public endpoint of the ApsaraDB for Redis instance. Copy the public endpoint and rerun the ping command.

   Important

   • If the public endpoint is not displayed in the console, click Apply for Endpoint in the Actions column. For more information, see Apply for a public endpoint for an ApsaraDB for Redis instance.

   • You cannot apply for public endpoints for cloud disk-based cluster instances in direct connection mode.

2. If the public endpoint used to connect to the instance is correct but the instance still fails to be pinged, check whether the domain name resolution fails. For more information, see Troubleshoot connection issues caused by failed DNS resolution.

Step 3: Run the telnet command to check whether the service port is available

Procedure

Run the telnet command on the on-premises device.

telnet <host> <port>

Example: telnet r-bp1zx****.redis.rds.aliyuncs.com 6379

Result description

If Connected to ... is returned or the telnet interface is displayed as shown in the following figure, the connection is established.

If the "Connection timed out" or "Connect failed" message is displayed, the connection fails.

Common causes and solutions

The whitelist is incorrectly configured or no whitelist is configured. For more information, see Step 4: Check the whitelist.

Step 4: Check the whitelist

In most cases, connection failure occurs because the whitelist is incorrectly configured or no whitelist is configured. In the following two scenarios, we recommend that you check the whitelist:

• The domain name can be pinged, but the telnet operation fails.

• If you use redis-cli to connect to the public endpoint of the ApsaraDB for Redis instance from the on-premises device, the (error) ERR illegal address or (error) ERR client ip is not in whitelist error message appears.

Common causes

• The whitelist is incorrectly configured. The public IP address of the on-premises device is not added to the whitelist.

• No whitelist is configured.

Solution

1. Query the public IP address of the on-premises device.

   • Linux: Open the CLI, enter the curl ifconfig.me command, and then press Enter.

   • Windows: Open Command Prompt, enter the curl ip.me command, and then press Enter.

   • macOS: Start Terminal, enter the curl ifconfig.me command, and then press Enter.

2. Add the retrieved public IP address to the whitelist of the ApsaraDB for Redis instance. For more information, see Configure whitelists.