OracleTNS-12535: TNS: Operation timeout

Ldquo; TNS-12535: TNS: Operation timeout rdquo. Linux Firewall shutdown command: serviceiptablesstop or chkconfigipta

Ldquo; TNS-12535: TNS: Operation timeout rdquo. Linux Firewall shutdown command: service iptables stop or chkconfig ipta

Recently I encountered the problem of "TNS-12535: TNS: Operation timeout.

1. First, check whether the server has enabled the firewall. The firewall blocks connections.
Linux Firewall shutdown command: service iptables stop or chkconfig iptables off
2. Go to the Oracle root directory and open the ora10g \ network \ admin \ tnsnames. ora file. This is the network connection configuration file, and check whether the IP address and other configurations are correct. For example, if I establish a connection with the host whose IP address is 192.168.1.1 and the name is Test, you will find this section in this file:
Orcl =
(DESCRIPTION =
(ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP) (HOST = 10.25.30.77) (PORT = 1521 )))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl)
)
)

This should be done !!