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QSYSWRK subsystem on the AS/400 Telnet server sends a message (CPF8940)
indicating that a virtual device cannot be automatically selected.
If you change the QAUTOVRT value to 10, the next Telnet connection attempt
causes the Telnet server to create a virtual device. This virtual device is created
because the number of virtual devices on the controller (0) is less than the number
specified in the QAUTOVRT (10). Even if you change the specified number to 0
again, the next user attempting a Telnet connection succeeds. When a Telnet
connection attempt fails, the CPF87D7 message is sent to the system operator
message queue on the Telnet server system. The CPF87D7 message indicates that
the AS/400 server is not able to create a virtual device.
Security Considerations for Telnet Printer Pass-Through Mode
Printer sessions are always made active, immediately after session initialization,
which means that sign-on attempts are not necessary.
In Version 4 Release 2, the following level of support has been added with regard
to security of printer devices:
v You have the ability to deny connections
For more information on Telnet exit points and how to use them, see “TELNET Exit
Points” on page 541 in Appendix E. TCP/IP Application Exit Points and Programs.
Telnet and SNA 5250 Pass-Through Considerations for Telnet
Printer Pass-Through Mode
The AS/400 system supports 5250 pass-through. 5250 pass-through is similar to
Telnet; it runs on an SNA (Systems Network Architecture) protocol network rather
than a TCP/IP network. 5250 pass-through uses virtual displays to direct output to
the physical devices just as Telnet does. In 5250 pass-through, the AS/400 system
automatically creates virtual devices in the same way that it does for Telnet.
Therefore, the QAUTOVRT system value controls the number of automatically
configured virtual devices for both 5250 pass-through and Telnet. Other applications
use virtual devices also, for example, printer pass-through, Workstation Gateway,
and other IBM and non-IBM applications. For more information about 5250
pass-through, see the
Remote Work Station Support
book.
Step 3–Setting the Telnet Timemark Timeout Value
You should take into consideration the TIMMRKTIMO parameter.
The Telnet timemark timeout (TIMMRKTIMO) parameter specifies the number of
seconds between TIMEMARK commands sent by the Telnet server. If Telnet is
unable to send the TIMEMARK command, it closes the connection.
Step 4—Telnet Printer Pass-Through—Creating Virtual
Controllers and Devices
You can create virtual controllers and devices. If you create your own virtual
devices, by allowing the system to automatically select the device name, you must
be aware of the following:
v The virtual controller must be named QPACTLnn, where nn is a decimal number 01
or greater.
v The virtual device should be named QPADEVxxxx, where xxxx is an alphanumeric
character from 0001 to ZZZZ.
218 OS/400 TCP/IP Configuration and Reference V4R4