local login from DBA group member (as sysdba) not working good day!

i'm confronted with the following situation


OS: CentOS 7 x86_64
user: oracle (member of DBA group, owner of /u01/app (drwxr-sr-x)
/etc/oratab: orcl12c:/u01/app/oracle/product/12.1.0/dbhome_1:Y
after starting LISTENER manually, Listener reports "The listener supports no services" 
sqlplus sys/*@co7ora12cvm:1521/orcl12c as sysdba returns
«ORA-12514: TNS:listener does not currently know of service requested in connect descriptor»
dbstart starts listener but errors out with ORA-01017: invalid username/password; logon denied
i'm able to start the database through dbca (Configure database options > Next > Next)
once this is done LISTENER know of the services orcl12c and orcl12cXDB
once this is done, sqlplus username@orcl12c works fine
sqlplus as sysdba throws the /? output.
ping co7ora12cvm works
tnsping orcl12c times out (TNS-12535)


listener.ora

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = co7ora12cvm)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
  )



shrept.lst

(##) function entry points for genclntsh.sh

network : snaumihi_inithostinfo
network : snaumbg_gmt
network : naedpwd_encrypt
network : naumbsb_bld_singlebyte
network : nlgh
network : nsdhctx_establish
network : nsdhctx_respond
network : nsdhctx_close
network : nsdhctx_inuse
network : snlsmDscFromString
network : snlsmCreate
network : snlsmDestroy
network : snlsmDscToString


sqlnet.ora

SQLNET.AUTHENTICATION_SERVICES = (NONE)


tnsnames.ora

ORCL12C =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = co7ora12cvm)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = orcl12c)
    )
  )


this is a new install that has never started "normally"

thanks in advance for any suggestion

############# UPDATE user/hosts

as already mentioned i do this as user oracle which is member of the dba team

this is run on vmware and i do the networking with the hosts files

/etc/hosts on co7ora12vm

127.0.0.1       localhost.localdomain localhost
192.168.178.30&lt;>co7ora12cvm.localdomain co7ora12cvm


c:\windows\System32\drivers\etc\hosts (on Windows 7)

192.168.178.30          co7ora12cvm.localdomain co7ora12cvm


############# UPDATE sqlnet.ora

thanks for spotting this, indeed, alas it makes no difference


sqlplus sys/sys@co7ora12cvm:1521/orcl12c as sysdba gives ORA-12514: TNS:listener does not currently know of service requested in connect descriptor  before  instance is started through dbca; once instance is started it connects
sqlplus / as sysdba  always gives ORA-12162: TNS:net service name is incorrectly specified


this happens no matter what sqlnet.ora contains


SQLNET.AUTHENTICATION_SERVICES = ()
SQLNET.AUTHENTICATION_SERVICES = (NONE)
NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT) such as on my 10g vm where sqplus / as sysdba works


?
You have disabled local OS authentication by setting this:

SQLNET.AUTHENTICATION_SERVICES = (NONE)

Remove the above line from sqlnet.ora, after that, you will be able to log in to the database with:

sqlplus / as sysdba