nstrtel.5 (2010 09)

n
nstrtel(5) nstrtel(5)
(Tunable Kernel Parameters)
NAME
nstrtel - specifies the number of telnet device files the kernel can support for incoming telnet sessions
VALUES
Failsafe
60
Default
60
Allowed values
Any positive integer. (Subject to available physical memory.)
It is best to use the default value, and there should not be any need to lower it. However, if the simul-
taneous telnet connection load is very high, then the value of
nstrtel could be increased.
Recommended values
60 (Default value.)
DESCRIPTION
The telnet daemon uses two STREAMS-based pseudo-terminal drivers (
telm and tels). The kernel
parameter,
nstrtel, can be used to tune the number of pseudo-terminals.
nstrtel specifies the
number of kernel data structures that are created at system boot time that are required to support the
device files used by incoming telnet sessions on a server. If the
insf command or SAM is used to create
more telnet device files, the value of nstrtel must be increased accordingly or the device files cannot be
used because there are no kernel data structures available for communicating with the system.
Who Is Expected to Change This Tunable?
Anyone.
Restrictions on Changing
Changes to this tunable take effect at the next reboot.
When Should the Value of This Tunable Be Raised?
When there is an increase in the load of telnet connections and there are no device files available to open
telnet connections, then this kernel parameter should be increased.
When the
telnetd: Telnet device drivers missing: No such device, error is
encountered, then the device files have been exhausted and nstrtel should be raised. Once the value
of nstrtel is raised, insf should be run to create new device files. (If SAM is used to raise the value
of nstrtel, insf is run automatically.)
What Are the Side Effects of Raising the Value of This Tunable?
More resources would be consumed. Extra kernel data structures, and extra device files may clog the sys-
tem.
When Should the Value of This Tunable Be Lowered?
It is not advisable to lower the tunable value from the default value. Consult HP Support before lowering
this tunable from the default value.
What Are the Side Effects of Lowering the Value of This Tunable?
Though not recommended, there would not be any side effects.
What Other Tunables Should Be Changed at the Same Time?
None.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its
meaning changed in future releases of HP-UX.
Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parame-
ter values. After installation, some tunable parameters may no longer be at the default or recommended
values. For information about the effects of installation on tunable values, consult the documentation for
the kernel software being installed. For information about optional kernel software that was factory
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1