If you try to connect with sysdba from client machine, it might give you the following error
ORA-01031: insufficient privileges
You need to create the password for in $ORACLE_HOME/dbs location, and following is an example to create the password file.
$ orapwd file=$ORACLE_HOME/dbs/orapwSID password=type_password entries
once you run this command on the Oracle Server, then again try to login from the client with sysdba, it will work.