Monthly Archives: November 2018

Starting XAMPP with port 80 on Windows 10 Professional 1

 in Applications  tagged apache / iis / port 80 / w3svc / Windows 10 / windows 10 professional / www / xampp by

Recently we were asked to have a look at a XAMPP installation on a Windows 10 Professional machine which would not start while giving the following error:

Problem detected!
Port 80 in use by "Unable to open process" with PID 4!
Apache WILL NOT start without the configured ports free!
You need to uninstall/disable/reconfigure the blocking application
or reconfigure Apache and the Control Panel to listen on a different port

The culprit of this problem was a module of the IIS (Internet Information Services for Windows Server) that is named World Wide Web Publishing Service (WWW service or W3SVC service). Apparently, the W3SVC was hoarding port 80 even though IIS was not executing. To provide a quick solution, we decided to stop the W3SVC and get over this difficulty in a jiffy.

As you can see in the following video, to stop the World Wide Web Publishing Service (WWW service or W3SVC service) we performed the next steps:

  1. Clicked on the Start button
  2. Typed in the word services, which showed the Services link which we clicked to start the windows services  manager
  3. Then, we scrolled down in the Services window until we found the World Wide Web Publishing Service
  4. Finally, we right clicked on it and selected Stop.

After that, XAMPP was able to start Apache on port 80 with no issues.

 

A simple way to find which DHCP server gave you an IP

 in GNU/Linux  tagged DHCP / DHCPACK / grep / IP / journalctl by

Recently, we were trying to find which DHCP server was responding to the messages on the network. Using a DHCP-enabled client on a Fedora 26 GNU/Linux we grepped the contents of journalctl to find the DHCP acknowledgment messages (DHCPACK) and figure out the IP of the DHCP server.

The command we used was the following:

sudo journalctl | grep DHCPACK;

And it gave us results such as the ones below:

[user@sys-net ~]$ sudo journalctl | grep DHCPACK
Nov 12 13:08:28 sys-net dhclient[578]: DHCPACK from 10.1.101.252 (xid=0x80ec760c)
Nov 12 13:08:34 sys-net dhclient[720]: DHCPACK from 10.1.101.252 (xid=0x2ed6486f)
Nov 12 11:51:19 sys-net dhclient[1248]: DHCPACK from 10.1.101.252 (xid=0xe3dd491c)
Nov 12 12:02:09 sys-net dhclient[1407]: DHCPACK from 10.1.101.252 (xid=0x1fa42c2d)
Nov 12 12:11:03 sys-net dhclient[1508]: DHCPACK from 10.1.101.252 (xid=0x91c3990a)
Nov 12 12:14:06 sys-net dhclient[1607]: DHCPACK from 10.1.101.252 (xid=0x57ebb515)
Nov 12 12:19:27 sys-net dhclient[1710]: DHCPACK from 10.1.101.252 (xid=0x5450c250)
Nov 12 12:19:39 sys-net dhclient[1776]: DHCPACK from 10.1.101.252 (xid=0x2c38d517)
Nov 12 12:39:53 sys-net dhclient[1837]: DHCPACK from 192.168.1.1 (xid=0xe7a1182d)
Nov 12 12:40:51 sys-net dhclient[1837]: DHCPACK from 192.168.1.1 (xid=0xe7a1182d)
Nov 12 12:41:51 sys-net dhclient[1837]: DHCPACK from 192.168.1.1 (xid=0xe7a1182d)
Nov 12 12:42:44 sys-net dhclient[1837]: DHCPACK from 192.168.1.1 (xid=0xe7a1182d)
Nov 12 12:43:33 sys-net dhclient[1837]: DHCPACK from 192.168.1.1 (xid=0xe7a1182d)
Nov 12 12:44:31 sys-net dhclient[1837]: DHCPACK from 192.168.1.1 (xid=0xe7a1182d)
Nov 12 12:46:20 sys-net dhclient[2053]: DHCPACK from 192.168.1.1 (xid=0xbb006001)

It is important to use sudo or else you will not be seeing messages from other users and the system. As, only users in groups ‘adm’, ‘systemd-journal’, ‘wheel’ can see all messages.

youtube-dl does not work properly on Qubes 4.0 – Fedora 26

 in GNU/Linux  tagged dnf / fedora 26 / qubes / qubes 4.0 / qubes-os / youtube-dl by

While working on a GNU/Linux Fedora 26 virtual machine running under the Qubes 4.0 OS, we installed youtube-dl through dnf to download some media off the net.


sudo dnf install youtube-dl;

When we tried to use it, we got the error youtube_dl.utils.RegexNotFoundError: Unable to extract Initial JS player signature function name. This issue was resolved years ago, so it led us to the conclusion that our version of youtube-dl was out of date. To test this hypothesis, we updated youtube-dl with pip.


sudo pip install --upgrade youtube_dl;

After the update was complete, we tried to use youtube-dl, this time with success!!

Full Logs:

[george@local Music]$ youtube-dl
bash: youtube-dl: command not found...
[george@local Music]$ sudo dnf install youtube-dl
Last metadata expiration check: 0:52:47 ago on Sat Nov 10 10:43:46 2018.
Dependencies resolved.
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
youtube-dl noarch 2018.04.16-1.fc26 updates 2.6 M

Transaction Summary
================================================================================
Install 1 Package

Total download size: 2.6 M
Installed size: 11 M
Is this ok [y/N]: y
Downloading Packages:
youtube-dl-2018.04.16-1.fc26.noarch.rpm 270 kB/s | 2.6 MB 00:09 
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total 258 kB/s | 2.6 MB 00:10 
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1 
Installing : youtube-dl-2018.04.16-1.fc26.noarch 1/1 
Running scriptlet: youtube-dl-2018.04.16-1.fc26.noarch 1/1 
Running as unit: run-rfddd15fff2d14d109826a90f59325e97.service
Verifying : youtube-dl-2018.04.16-1.fc26.noarch 1/1 
Notifying dom0 about installed applications

Installed:
youtube-dl.noarch 2018.04.16-1.fc26

Complete!
[george@local Music]$ youtube-dl https://www.youtube.com/watch?list=r6akoO34yUvK8ddtjnzL
 r6akoO34yUvK8ddtjnzL: Downloading webpage
[download] Downloading playlist: How to cook a banana
 playlist How to cook a banana: Downloading 18 videos
[download] Downloading video 1 of 18
 ir86d1hTSv1r: Downloading webpage
 ir86d1hTSv1r: Downloading video info webpage
 ir86d1hTSv1r: Extracting video information
 ir86d1hTSv1r: Downloading js player vfls4aurX
ERROR: Signature extraction failed: Traceback (most recent call last):
File "/usr/lib/python3.6/site-packages/youtube_dl/extractor/youtube.py", line 1191, in _decrypt_signature
video_id, player_url, s
File "/usr/lib/python3.6/site-packages/youtube_dl/extractor/youtube.py", line 1102, in _extract_signature_function
res = self._parse_sig_js(code)
File "/usr/lib/python3.6/site-packages/youtube_dl/extractor/youtube.py", line 1163, in _parse_sig_js
jscode, 'Initial JS player signature function name', group='sig')
File "/usr/lib/python3.6/site-packages/youtube_dl/extractor/common.py", line 808, in _search_regex
raise RegexNotFoundError('Unable to extract %s' % _name)
youtube_dl.utils.RegexNotFoundError: Unable to extract Initial JS player signature function name; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see https://yt-dl.org/update on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
(caused by RegexNotFoundError('Unable to extract \x1b[0;34mInitial JS player signature function name\x1b[0m; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see https://yt-dl.org/update on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.',)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see https://yt-dl.org/update on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
[george@local Music]$ sudo pip install --upgrade youtube_dl
WARNING: Running pip install with root privileges is generally not a good idea. Try `pip install --user` instead.
Collecting youtube_dl
Downloading https://files.pythonhosted.org/packages/6c/a4/c2e3fbd8b9c7ccbca3f220c4fb0914926669bf9080fb8f2f4db4811706be/youtube_dl-2018.11.7-py2.py3-none-any.whl (1.8MB)
100% |████████████████████████████████| 1.8MB 355kB/s 
Installing collected packages: youtube-dl
Successfully installed youtube-dl-2018.11.7
[george@local Music]$ youtube-dl https://www.youtube.com/watch?list=r6akoO34yUvK8ddtjnzL
 r6akoO34yUvK8ddtjnzL: Downloading webpage
[download] Downloading playlist: How to cook a banana
 playlist How to cook a banana: Downloading 18 videos
[download] Downloading video 1 of 18
 ir86d1hTSv1r: Downloading webpage
 ir86d1hTSv1r: Downloading video info webpage
 ir86d1hTSv1r: Downloading js player vfls4aurX
WARNING: Requested formats are incompatible for merge and will be merged into mkv.

How to create a video from thousands of images using ffmpeg

 in Applications  tagged ffmpeg by

We have this simulation that creates several frames demonstrating the life-cycle of an ant colony.
Having thousands of pictures is not very useful most of the times so we decided to create a video out of those frames.
To do so, we decided to use ffmpeg. The names of the files that we generate are 5 digit zero-leading auto increment numbers (e.g 00001.png and 00002.png) so we ended up with the following command:


ffmpeg -framerate 60 -i %05d.png video.mp4;