TNS-12560: TNS:protocol adapter error on Oracle Enterprise Linux

Question

hi,
I am getting -
TNS-12560: TNS:protocol adapter error when I try to connect the Db installed on Oracle Enterprise Linux from other machines.
I made all the .bash_profile changes and created one shared listener also to check whether there is any problem with the dedicated default listener or its port.
Please suggest the solution .
Regards
sumit chaudhary

Answer 1

You need to open the firewall on OEL.
Edit the contents of /etc/sysconfig/iptables file. I added the line in bold:
# Firewall configuration written by system-config-securitylevel
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A FORWARD -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -p 50 -j ACCEPT
-A RH-Firewall-1-INPUT -p 51 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp --dport 5353 -d 224.0.0.251 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INPUT -m state state NEW -m tcp -p tcp dport 22 -j ACCEPT
*-A RH-Firewall-1-INPUT -m state state NEW,ESTABLISHED,RELATED -m tcp -p tcp dport 1521 -j ACCEPT*
-A RH-Firewall-1-INPUT -m state state NEW -m udp -p udp dport 137 -j ACCEPT
-A RH-Firewall-1-INPUT -m state state NEW -m udp -p udp dport 138 -j ACCEPT
-A RH-Firewall-1-INPUT -m state state NEW -m tcp -p tcp dport 139 -j ACCEPT
-A RH-Firewall-1-INPUT -m state state NEW -m tcp -p tcp dport 445 -j ACCEPT
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT
As you can see, my listener port is 1521.
Do not put that line after the line with REJECT keyword ( it won't work then) !
Save and close the file. Restart iptables:
/etc/init.d/iptables restart
Now you can connect from the outside.
It works on my OEL version 5 update 4.