SQL> create or replace trigger system.check_ip_addresses
  2  after logon
  3  on database
  4  declare
  5  i_ip_address varchar(16) := sys_context ('USERENV','IP_ADDRESS');
  6  BEGIN
  7  IF USER IN('SCOTT','HR')THEN
  8  IF i_ip_address = '10.10.2.1' THEN
  9  NULL;
 10  ELSE
 11  RAISE_APPLICATION_ERROR(-20000,'Can not log in from this IP address ( ' ||
i_ip_address ||')
 12  end if;
 13  end if;
 14  end;
 15  /

Warning: Trigger created with compilation errors.

SQL> show errors
Errors for TRIGGER SYSTEM.CHECK_IP_ADDRESSES:

LINE/COL ERROR
-------- -----------------------------------------------------------------
8/91     PLS-00103: Encountered the symbol ")
         end if;
         end if;
         end;" when expecting one of the following:
         ( - + case mod new null <an identifier>
         <a double-quoted delimited-identifier> <a bind variable>
         continue avg count current max min prior sql stddev sum
         variance execute forall merge time timestamp interval date
         <a string literal with character set specification>
         <a number> <a single-quoted SQL string> pipe
         <an alternatively-quoted string literal with character set

LINE/COL ERROR
-------- -----------------------------------------------------------------
         specification>
         <an alt

SQL>