cannot connect dba account as sysdba from client sqlplus

I have an account established with dba privileges (on 8.1.6) that can connect to the db with sysdba privileges using sqlplus command line from the linux prompt. This account cannot connect with sysdba privileges from a client (8.1.7) machine using SQL*Plus.

My init.ora param os_authent_prefix = ""

How can I get connect the dba account with sysdba privileges from the client machine?

Thanks

You need to set up a password file and add that user to it. See "Password File Authentication" in the Oracle Admin Guide.

Use orapwd

Thanks Tom and Dilip got it working.

These are the steps I took:
1) revoke SYSDBA /SYSOPER privileges from the accounts
2) shutdown databse
3) use orapwd utility to create password file
4) set init.ora param remote_login_passwordfile
5) restart database