unable to login oracle as sysdba
The problem was I was using the variable TWO_TASK. Once I unset the variable, I nolonger had issues logging in a sysdba.

$ unset TWO_TASK
$ sqlplus /nolog

SQL*Plus: Release 11.2.0.1.0 Production on Wed Feb 6 02:51:55 2013

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

SQL&gt; conn / as sysdba
Connected to an idle instance.
SQL&gt; startup;
ORACLE instance started.

Total System Global Area 1707446272 bytes
Fixed Size          1336988 bytes
Variable Size         989858148 bytes
Database Buffers      704643072 bytes
Redo Buffers           11608064 bytes
Database mounted.
Database opened.
SQL&gt; exit


I found the answer here.