Connections from client results in ORA-12560

Another encounter with ORA errors, this time it is ORA-12560 when I attempt to connect to database from clients(in my case using TOAD).

"TNS-12560: TNS:protocol adapter error"

Now few blogs do give details about a structured approach to resolve this error. However to begin troubleshooting I wanted to make sure if port 1521 is open.

"telnet" to rescue, this can be used to verify if the port is open.

C:\Documents and Settings\ telnet 192.168.1.200 1521 ---> # telnet ipaddress port number
If this is successful port is open, in my case port was closed so it failed & I was looking to sort this one first.


Server has RHEL installed on it.

As a root user, add the below line before the commit part
# vi /etc/sysconfig/iptables
Append rule as follows:

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 1521 -j ACCEPT

Save and close the file. Restart iptables:

# /etc/init.d/iptables restart

Run a telnet session to test if port is open now, it was open & I can go ahead & start using clients to connect to Database.


I hope this reaches out to the needy & guides them get over the ORA-12560... Good luck & stay tuned for more... Cheers ..:)