[Xastir] Interface Problem

[Curt, WE7U]

On Wed, 8 Dec 2004, Andrew Rich wrote:

> A hard fail means that the filehandle is tied up by some other process.
> If you are running a TNC hooked up to a com port, you should run either
> "Serial TNC" or "Serial KISS TNC".

For Cygwin, yes, those are his main choices.  Or AGWPE.


> Unless you are running AX25 Kernel support under LINUX, you should not
> touch the "AX25 TNC" setting.

Correct.


> Permissions has nothing to do with anything.

Well, almost nothing, see below.


> You are running xastir, to
> get the hard fail message, so your permissions are ok for the program.
> I do not know who / how you want to mess with that.

There are another few flags that can be set in the "permissions"
area for an executable that do some very weird things.  One is the
SUID bit, another is the SGID bit.  SUID is the one we're setting on
the executable.  If you become root and set this bit, then when the
executable is run by a non-root user, the program assumes root
user privileges while running.  It's very cool, and very scary at
the same time.

We've gone through our code on several occasions with an eye towards
security.  A lot of changes have been done to minimize possible
security holes.  The main thing is that Xastir itself drops root
privileges during normal operations, then assumes them for brief
periods when it has to, such as while opening AX.25 kernel
networking ports.  We don't guarantee that someone can't find a way
to get into your system via Xastir and take over as root, but we've
attempted to minimize the risks of that happening.

Jerry doesn't need to know that stuff/doesn't need to run the chmod
command, as chmod is not useful on Cygwin.  On Windows/Cygwin,
there is no "root" user.  All unixy things on Cygwin run with full
privileges (of the logged-in Windows user) in all cases.  You can't
gain Administrator privileges in Cygwin, nor are there multiple
levels of privilege above or below the user level inside Cygwin.


> Please make sure nothing else is using the Serial port when you are
> running XASTIR.

That's the main thing.  And check the permissions on your serial
ports as well.

Things I would do:

*) ls -l /dev/ttyS*

    Check permissions there.

*) ls -al /var/lock

    Check for lock files that have ttyS0/ttyS1 in the name.  Lock
    files are created on Unixy systems when a device is needed
    exclusively.  Other programs should normally look for lock files
    before opening the device.

--
Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
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