ORA-01031: insufficient privileges connecting to standby
According to the output of the command ps -ef|grep pmon which has shows that the instance name of the standby database is teststan.


[oravis@standbysrv ~]$ ps -ef|grep pmon oravis 2749 1 0 16:02 ? 00:00:00 ora_pmon_teststan oravis 2825 2697 0 16:03 pts/0 00:00:00 grep pmon


But in the description of listener on standby database, SID_NAME is defined as 'test'. 

The Oracle tries to authenticate sys user using password file(orapwtest) which has never existed. 
So set the SID_NAME parameter on listener.ora file on standby site to 'teststan'.