tnsping + 12560 protocol adaptor error

redhat 5.2 10gr2 (10.2.0.4)

i was getting error while trying to tnsping standby server

$tnsping orcldg 10
error: tns 12560 protocal adaptor error

NOTE: orcldg is a name of standby database

after little searched i found the below details

clause:
port 1521 is blocked on standby server

we can check port is blocked or not by below command

cmd>telnet servername 1521
connection failed --- this command failed if port is blocked

solution:
on standby server connect with root user and execute the following command to disable firewall and unblock 1521 port

# /etc/init.d/iptables save
# /etc/init.d/iptables stop



NOTE: if you want to again block or enable firewall setting then execute the following command

# /etc/init.d/iptables start