[Fixed] CLOUD-0005: Unable To Establish Connection

This post covers an Error encountered while Creating Database Adapter/Connection as part of our Hands-On-Lab Exercise for Module 4 (Create Database Adapters in OIC) from our Oracle Integration Cloud Services (OIC) Training Program.

If you are new to Oracle Integration Cloud (OIC), then check out our blogs below as these contain all the key points that a beginner should know about Oracle Integration Cloud (OIC), creating Oracle Integration Instance and Consoles walkthrough.

Error: CLOUD-0005: Unable To Establish Connection

There are many reasons for this error to occur, Let’s start with the pre-checks you should follow to pinpoint the error.

PRE-CHECKS

Check the provided hostname.
Port 1521 may not be open.
Connectivity Agent could be down
Database Might be down.

Check 1. The provided Hostname is Invalid

1. Click on the hamburger menu and go to Bare Metal, VM, and Exadata.

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

2. Click on the DB system that you have created.

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

3. Make sure you have used the Scan DNS Name in Host, not Host Domain Name.

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

4. If your host is correct the try using the IP Address of DB instead of Scan DNS Name.
5. Click on Nodes and copy the Public IP Address and use it in Host for DB connection.

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

6. Now test the connection again If it fails again then there might be something else that may be causing this error.

Check 2. Port 1521 must be closed

By default, the port 1521 is not open in Oracle Cloud and it has to be opened manually.

Steps to check if port 1521 is accessible or not

1. Open CMD
2. Enter command telnet followed by Public IP of your DB then followed by port 1521.

telnet 129.146.165.110 1521

3. Now the Command line will get clear and you will be able to see that the telnet command is a success.

4. If the telnet fails then you need to open port 1521.

Steps to Open port 1521

2. Click on the DB system that you have created.

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

3. Click on VCN.

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

4. Click on Security Lists from Resources which is associated with your VCN.

5. Click on Default Security List

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

6. Check if there is an ingress rule for port 1521 if not then click on Add Ingress Rule.

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

7. Enter the below details and click on Add Ingress Rules
a) Source CIDR 0.0.0.0/0
b) IP Protocol TCP
c) Destination Port Range 1521

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

8. Now you can see an ingress rule is added

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent
9. Now Test the connection again.

Check 3. Ensure that your Connectivity Agent is up and running

1. Open you DB VM in Putty

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

2. Go to the directory where the agent is located.
3. Start you, connectivity agent, using command Java -jar connectivityagent.jar
4. If your Connectivity Agent is down then you will get this message saying Agent started successfully...Now available for new messages…

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

5. If your agent was up and running then you will get a message saying Agent is already running for this particular instance!!!

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

Check 4. The DataBase Should be Up and Running

1. Open your DB VM using putty.
2. Switch user to Oracle
3. Login into sqlplus using command sqlplus / as sysdba
4. Type command startup to start the database.
5. If you DB is already up and running then you will get an error message and it rules out this case.

CLOUD-0005: unable to establish connection OIC oracle cloud integration DB System databse VCN port security list putty ingress rule connection adapter connectivity agent

This blog is part of our Oracle Integration Cloud (OIC) blog series stay tuned for our future posts where we will troubleshoot more issues like this.

Conclusion

This blog resolved the cause if Error CLOUD-0005: Unable To Establish Connection by using a systematic checklist to rule out what is causing this error and how to resolve it.

Next Task for you:

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