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Re: telnet: tcp/telnet: unknown service

Jose Luis Fernandez wrote:

> After doing a lot more googleing, I've stumbled upon
> this fix.  Wonder
> if you know about this issue?
> In regedit go to
> HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
> edit DataBasePath change %SystemRoot% to its real
> value (on mine its
> C:\WINDOWS)  Don't know why but this fixed my issue.

Well, that may work but it's suboptimal.  The real fix is to ensure that
the environment variable SYSTEMROOT is always set, which is normally
done by Windows without the user having to do anything.  Unsetting this
may cause any number of things to break, and this may only be one of
them -- even if your particular telnet problem is solved you need to
make sure that SYSTEMROOT isn't being unset somewhere.

You see this happen sometimes when an app spawns a child process (such
as CGI) and tries to be clever about clearing its environment of
unnecessary things.  If SYSTEMROOT is one of them, random thing start
breaking.  There is code in Cygwin to try to prevent this from ever
happening, but this obviously is of no use to non-Cygwin programs or
programs that go behind Cygwin's back (such as by calling the win32 API

Another version of this problem crops up if some program (perhaps a
brain-dead installer) changes this particular registry key from a
REG_EXPAND_SZ to a standard string (REG_SZ) type, in which case the
environment variable will not be expanded.  It must be type


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