Testing telnet connections in a script


 
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Old 01-12-2007
Testing telnet connections in a script

Hi,

I am trying to figure out how to test to see if a server is accepting telnet connections via a script.

I have several remote MPE servers that are set in single user mode (and hence not accepting telnet connections), for their backups, I want to try and automate a test (from a unix server), to see if telnet connections are available and hence if the servers are still in single user mode.

Hmm ... not sure how clear that was ... I basically want to do something like this:

while true
do
telnet <server_name> > richtmp &
echo $! > richtmp.PID
***some kind of grep thing on 'richtmp' to see if the connection worked***
kill `cat richtmp.PID`
sleep 60
done


.... but more elegantly. Is there an option to the telnet command that will do this?

many thanks,

Richard
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nstrtel(5)							File Formats Manual							nstrtel(5)

NAME
nstrtel - specifies the number of telnet device files the kernel can support for incoming telnet sessions VALUES
Failsafe Default Allowed values (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 simultaneous telnet connection load is very high, then the value of could be increased. Recommended values (Default value.) DESCRIPTION
The telnet daemon uses two STREAMS-based pseudo-terminal drivers and The kernel parameter, can be used to tune the number of pseudo-termi- nals. 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 command or SAM is used to create more telnet device files, the value of 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 error is encountered, then the device files have been exhausted and should be raised. Once the value of is raised, should be run to create new device files. (If SAM is used to raise the value of 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 system. 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 parameter values. After installation, some tunable parameters may no longer be at the default or recommended values. For information about the effects of installation on tun- able values, consult the documentation for the kernel software being installed. For information about optional kernel software that was factory installed on your system, see at AUTHOR
was developed by HP. SEE ALSO
insf(1M), telnetd(1M), telm(7), tels(7). Tunable Kernel Parameters nstrtel(5)