ORA-12170

ORA-12170: TNS:Connect timeout occurred

What causes this error?

An ORA-12710 error occurs when SQL*Net cannot connect to its destination. Common causes are firewalls blocking connections and network routing errors.

How to fix it

Open firewall to allow SQL*Net connections through

Open firewall settings and ensure the listener port is not blocked.

For example, on a Windows system, navigate to Control Panel-> Security Center-> Windows Firewall-> Exceptions. Click on Add port and add TCP port 1521 or whatever port the listener is running on (see listener.ora).

Troubleshoot networking between two systems

Use utilities like ping, tnsping, netstat and traceroute to see if the two systems are connected on the network.