You may need to change the permissions on the "/VAR/TMP/.ORACLE" file.
In order for the Listener to open a socket, oracle must have write
access on
"/var/tmp/.oracle". Do the following:

1) % cd /var/tmp

2) Either change the ownership and group of the ".oracle" directory to
"oracle/dba":

# chown oracle .oracle
# chgrp dba .oracle

or

Change the permissions on the directory:

# chmod 777 .oracle


Solution Explanation:
=====================

Upon starting the Listener, an IPC socket file is created in
"/var/tmp/.oracle". Thus, "/var/tmp/.oracle" must be writable by the
oracle
user.