ORA-12170: TNS: Connect timeout occurred tips
Oracle Database Tips by Donald BurlesonConsulting
I'm getting the error "ORA-12170:
TNS:Connect timeout occurred" when I try to connect to my
database via OEM. How do I resolve the "ORA-12170: TNS:
Connect timeout occurred" error?
error can be for many reasons, firewall issue, database down,
listener down, bad sqlnet.ora parm, network trouble, etc.
The docs note:
ORA-12170: TNS:Connect timeout occurred
Cause: The server shut down because connection establishment or
communication with a client failed to complete within the allotted time
interval. This may be a result of network or system delays; or this may
indicate that a malicious client is trying to cause a Denial of Service
attack on the server.
Action: If the error occurred because of a slow network or system,
reconfigure one or all of the parameters SQLNET.INBOUND_CONNECT_TIMEOUT,
SQLNET.SEND_TIMEOUT, SQLNET.RECV_TIMEOUT in sqlnet.ora to larger values. If
a malicious client is suspected, use the address in sqlnet.log to identify
the source and restrict access. Note that logged addresses may not be
reliable as they can be forged (e.g. in TCP/IP).
Your sqlnet.ora file can be
found in your $ORACLE_HOME/network/admin directory.
ORA-12170 and hosts file
Verify that your /etc/hosts file has a
In Windows XP, make your hosts
file is located at win/system32/driver/etc/ and on UNIX, Linux,
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