SQL*Net configuration on the PC using newer versions of the
Oracle Client Software is very easy. The best (and easiest) way
of achiving a fully working client installation is to use the
SQL*Net Easy Configuration tool supplied by Oracle.
This toolhas a wizard type interface to take you through the
installation of the tnsnames.ora and
sqlnet.ora files.
Select "Add Database Alias" and enter a name for the alias when prompted. This alias is the name you will refer to the database instance as, and as such should be the same as the instance name (orcl in this case).
Select TCP/IP as the protocol, and when prompted the hostname of the machine hosting the database and the instance name of the database.
That's it.
However, if you do not have the SQL*Net Easy
Configuration Tool then don't worry. You can simply create
the tnsnames.ora and the sqlnet.ora
files in the $ORACLE_HOME/network/admin directory on
the client exactly as they are on the server. This will provide
an alias the same as on the server (always a good idea anyway).
UNIX clients are not very different that windows clients. If you
have the Network Manager from Oracle then user that
in the same way as above, if not then you can, again, just use
the same configuration files as the server in the
$ORACLE_HOME/network/admin directory.