Can I debug busybox program running on a qemu virtual machine using gdb?

[Tom Mitchell]

On Thu, Jul 7, 2022 at 2:27 AM Chan Kim <ckim at etri.re.kr> wrote:
>
> Hi all,
>
> I'm trying to track how tftp program runs when I run tftp provided by
> busybox on qemu virtual machine.
> I can debug the linux source but I cannot debug tftp (busybox) program.
> Can I debug busybox program using gdb in this case?
> Any hint or advice will be very appreciated.
> Thank you!

Check the tftp options for verbose flags.   The granularity of gdb is finer
than most connection problems.

tftp in busybox may be a subset of stand alone tftp.
fire it up and see what "help" and other commands tell you.

As always tftp has two parts.
Near and far.    Both the server and the client have verbos
the server may log authentication or other errors.

It would help to run standalone tftp on a laptop and also install busybox in
a scratch location to see if there are differences you care about.
As a security risk tftp is full of troubles so firewalls and switches
can drop traffic.
gdb is too fine.   If you are building it add classic print statements
to the verbose mode.
Two programs, two firewalls, is the network local or wild west big
with multiple hops and firewalls.