working with os authenticated users

OS authenticated users are those users who get authentication from operating system and oracle will accept them.
Certain parameters need to be set at oracle level for that
remote_os_authent
os_authent_prefix
for example above parameters need to be set as
remote_os_authent=TRUE
os_authent_prefix=ops$ which is default and can be set to null

create a os user as
useradd test10
passwd test10

create a oracle user as
create user ops$test10 identified externally;
grant connect to ops$test10;

now login into test10 as os user
su - test10
set environment variable PATH and ORACLE_HOME accordingly to execute sqlplus
remember to check permissions while setting above otherwise
$ sqlplus
Error 6 initializing SQL*Plus
Message file sp1<lang>.msb not found
SP2-0750: You may need to set ORACLE_HOME to your Oracle software directory
will come
once done
connct to oracle as
sqlplus /@SERVICENAME

check the above SERVICE is running and accessible properly first at oracle level