Debugging

Debugging Kismet

Kismet (especially in beta) is in a state of rapid development - this means that bad things can creep into the code. Sorry about that!

If you’re interested in helping debug problems with Kismet, here’s the most useful way to do so:

Compile Kismet from source (per the quick start guide above)
Install Kismet (typically via sudo make suidinstall)
Run Kismet, FROM THE SOURCE DIRECTORY, in gdb:

  $ gdb ./kismet

This loads a copy of Kismet with all the debugging info intact; the copy of Kismet which is installed system-wide usually has this info removed; the installed version is 1/10th the size, but also lacks a lot of useful information which we need for proper debugging.

Tell GDB to ignore the PIPE signal
```
(gdb) handle SIGPIPE nostop noprint pass
```
This tells GDB not to intercept the SIGPIPE signal (which can be generated, among other times, when a data source has a problem)
Configure GDB to log to a file

  (gdb) set logging on

This saves all the output to gdb.txt

Run Kismet - in debug mode

  (gdb) run --debug [any other options]

This turns off the internal error handlers in Kismet; they’d block gdb from seeing what happened. You can specify any other command line options after –debug; for instance:

  (gdb) run --debug -n -c wlan1

Wait for Kismet to crash
Collect a backtrace
```
   (gdb) bt
```

This shows where Kismet crashed.

Collect thread info
```
   (gdb) info threads
```

This shows what other threads were doing, which is often critical for debugging.

Collect per-thread backtraces
```
   (gdb) thread apply all bt full
```

This generates a dump of all the thread states

Send us the gdb log and any info you have about when the crash occurred; dragorn@kismetwireless.net or swing by IRC or the Discord channel (info available about these on the website, https://www.kismetwireless.net)

Advanced debugging

If you’re familiar with C++ development and want to help debug even further, Kismet can be compiled using the ASAN memory analyzer; to rebuild it with the analyser options:

    $ make clean
    $ CC=clang CXX=clang++ ./configure --enable-asan

ASAN has a performance impact and uses significantly more RAM, but if you are able to recreate a memory error inside an ASAN instrumented Kismet, that will be very helpful.