help sought - securing a terminal/line

[Guy Harris]

>We are looking at the same problem.  One solution suggested was to put
>the name of the program in the "/etc/ttys" file for that particular 
>terminal line.

If you have a 4.3BSD-style "/etc/ttys" file.  HP-UX probably has
"/etc/inittab" instead, which permits much the same thing to be done,
albeit with a different syntax.  S5's "init", not being as oriented
towards tty ports as is 4.3BSD's, will not automatically pass the tty
device name as an argument, as 4.3BSD's does; you have to pass it
explicitly.

In *both* cases, the program itself has to open the serial port (and
almost certainly wants to open it for reading/writing as file descriptor
0 and then dup it to FDs 1 and 2), and put it in the appropriate mode. 
It also may want to find out what kind of terminal is on that port, and
set the TERM environment variable appropriately.