To prevent application problems, dial-up lines that may be accidentally disconnected are often configured so that they can be physically disconnected without terminating the process. This presents a security risk, as a user can connect to the process simply by connecting to the line without having to login. Virtual terminals can be used to improve security on such lines because they only allow access to a disconnected process after going through the standard login procedure with the owner's name.
Virtual terminals also allow spawned processes to be controlled from a single terminal. Multiple independent processes can be controlled from a single terminal as well. Virtual terminals require some additional overhead. Refer to the OpenVMS documentation for more information.
Perform the following actions to enable virtual terminal operation, usually in SYS$MANAGER:SYSTARTUP_VMS.COM. See SYS$MANAGER:SYSTARTUP_VMS.TEMPLATE.
For VAX, invoke SYSGEN and issue the command connect/noadapter vta0/driver=ttdriver.
For Alpha, invoke SYSMAN 10 and issue the command connect VTA0 /noadapter/driver=sysloadable_images=ttdriver
In SYSGEN, set bit 17 of TTY_DEFCHAR2 ON to enable virtual terminals for all lines or OFF to disable them.
Issue the command: set term/perm/ [no]disconnect to adjust individual terminals with respect to the default.
Refer to your TCP/IP package's documentation for instructions on how to enable virtual terminals for the TELNET connection.