Client was getting Below error while connecting to the RAC database
sqlplus tester@RACDB_1
SQL*Plus: Release 10.2.0.4.0 - Production on Tue Sep 22 11:34:07 2020
Copyright (c) 1982, 2007, Oracle. All Rights Reserved.
ERROR:
ORA-12537: TNS:connection closed
Issue :
The Oracle Binary permissions got changed and was not allowing the connections
Current Permissions under Oracle Home
[oracle@host1 ~]$ ls -lrt $ORACLE_HOME/bin/oracle
-rwxr-sr-x 1 oracle asmadmin 243043788 Jun 2 01:12 oracle
It should be set to 6751 and should look like "-rwsr-s--x"
But doing chmod 6751 on oracle binary was not setting the correct permissions
[oracle@host1 bin]$ chmod 6751 oracle
[oracle@host1 bin]$ ls -lrt $ORACLE_HOME/bin/oracle
-rwsr-x--x 1 oracle asmadmin 243043788 Jun 2 01:12 oracle
Running below as RDBMS database Owner user helped , in this case "oracle" user
1) Stop the database instance where the permissions got changed
srvctl stop instance -d RACDB -i RACDB1
2) Run as Oracle Database owner, in this case its Oracle OS user.
[oracle@host1 ~]$ $GRID_HOME/bin/setasmgidwrap o=$ORACLE_HOME/bin/oracle
3) The permissions got changed and resolved the connection issues
[oracle@host1 ~]$ ls -lrt $ORACLE_HOME/bin/oracle
-rwsr-s--x 1 oracle asmadmin 243043788 Jun 2 01:12 oracle
Hope this resolves your issue..
