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ORA-12170: TNS:Connect timeout occurred


[edit] 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.

[edit] How to fix it

[edit] 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).

[edit] Troubleshoot networking between two systems

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