#Linux wireshark how to
#Linux wireshark code

(Pdb) b /usr/lib/python3.9/site-packages/asciinema/commands/upload.py:14īreakpoint 1 at /usr/lib/python3.In any packet-switched network, packets represent units of data that are transmitted between computers. Let's put a few breakpoints inside the UploadCommand (Lines 14, 26 on my copy of the code): SuricataLog]$ python3 -m pdb /usr/bin/asciinema upload demo-ascii.cast Self.print_error('retry later by running: asciinema upload %s' % self.filename) Self.print_error('upload failed: %s' % str(e)) Self.print(result.get('message') or result) usr/lib/python3.9/site-packages/asciinema/commands/upload.pyĪh, getting interesting! Let's open 'upload.py': from import Command usr/lib/python3.9/site-packages/asciinema/commands/_pycache_/ Was asciinema installed with an RPM (I use Fedora Linux)? SuricataLog]$ rpm -qif /usr/bin/asciinemaĪnd we are trying to upload a file, anything that looks like an uploader? SuricataLog]$ rpm -qil asciinema|grep -i uploa The program runs, hits the exception, and then it restarts at the beginning. To find out where the interesting stuff is, let's run the script through the Python pdb debugger: SuricataLog]$ python3 -m pdb /usr/bin/asciinema upload demo-ascii.cast The main script was generated with easy install, which means asciinema.py is just a wrapper around the interesting code. Sys.exit(load_entry_point('asciinema=2.0.2', 'console_scripts', 'asciinema')()) Globals().setdefault('load_entry_point', importlib_load_entry_point) If entry_oup = group and entry_point.name = name # for compatibility with easy_install see #2198įrom tadata import distributionįrom importlib_metadata import distributionįrom pkg_resources import load_entry_pointĭef importlib_load_entry_point(spec, group, name):įor entry_point in distribution(dist_name).entry_points # EASY-INSTALL-ENTRY-SCRIPT: 'asciinema=2.0.2','console_scripts','asciinema' Oh, yes we do! Ever curious, you open the asciinema script: #!/usr/bin/python3

usr/bin/asciinema: Python script, ASCII text executable

#Linux wireshark code

Can we dig further? If I only had the source code – deep diving with the Python debugger SuricataLog]$ file /usr/bin/asciinema So what is wrong? It is not that the site is down or unreachable. You can see on the about webpage that provides the hosting for asciinema. Openat(AT_FDCWD, '/etc/ld.so.cache', O_RDONLY|O_CLOEXEC) = 3įstat(3,. Time to see it in action: SuricataLog]$ strace asciinema upload demo-ascii.cast Strace is super useful when you don't have the source code of an application and yet you need to understand what is wrong when you call a program. System administrators, diagnosticians, and troubleshooters will find it invaluable for solving problems with programs for which the source is not readily available since they do not need to be recompiled in order to trace them. It is used to monitor and tamper with interactions between processes and the Linux kernel, which include system calls, signal deliveries, and changes of process state. What is strace? strace is a diagnostic, debugging, and instructional userspace utility for Linux. We will use a few tools to see what is going on here.

Is the destination a problem or is it an issue on my side?.

Which part of the protocol handshake is failing?.

What server and port does the tool try to use to upload the file?.

Then I decided to share it with the world.īut unlike the other recordings, this one refused to be uploaded: SuricataLog]$ asciinema upload demo-ascii.castĪsciinema: retry later by running: asciinema upload demo-ascii.castĪsciinema doesn't tell us much about the error. So I recorded an asciicast, using the cool Open Source project asciinema, for my small Open Source project SuricataLog. The Problem: Failing to upload a file to asciinema

#Linux wireshark how to

How to use some interesting features of the Python debugger.Basic usage of strace, nslookup, and RPM.I will give you enough information so you can follow along with the tutorial.

But it should be a good start.īefore we start you should be familiar with a few things:ĭon't worry too much. This list is not universal and, depending on what you are looking for, it may not be enough to solve your problem. In this article I will show you a few techniques you can use to troubleshoot a program when is not behaving.