Archives pour la catégorie ‘Logiciel’

Protect WordPress sites with .htaccess

28/04/2021 Comments off


Our job as WordPress users (aside from contributing to the WordPress community) is keeping our installs safe from people we do not want to access our sites. There are numerous plug-ins to help shore up our WordPress defenses such as Login LockDown which records IP address and blocks them after a set number of login attempts which helps against brute force attacks. Lire la suite…

System: fail2ban and iptables

23/04/2021 Comments off


Around the beginning of 2005 we saw an increase in brute-force ssh attacks – people or robots trying different combinations of username and password to log into remote servers. A quick search on this topic returns many references to iptables and ipchains but noone really explained how they work.

Having just gone through this learning curve myself, and found a satisfactory solution in the fail2ban package, I’m going to try and explain how to achieve the simple goal of banning IP addresses that make repeated failed ssh login attempts.

If you want more technical information regarding firewalls and iptables in particular, see the References section at the bottom of this page. Lire la suite…

Remove a Person From a Photo With Photoshop CS5’s Content Aware Feature

21/04/2021 Comments off


Final Product What You’ll Be Creating

With the launch of the new Adobe Suite of programs comes the long awaited Adobe Photoshop CS5. Packed with new features to speed up your workflow it truly is the most advanced edition of Photoshop to date. One of the new features we will be looking at today is called Content Aware. This feature allows you to quickly fill in a selection with surrounding content making it look like a part of the original image. In this case we will choose to remove a person from a photo, this can be done in less than five minutes. With the additional image enhancements this tutorial will take you less than 10 minutes to complete.


Original Image

Before we begin, download the image that we will be working with. As you can see, there are two individuals in this photo. In today’s tutorial, we will use Photoshop CS5′s Content Aware Feature to remove the man on the left.

Step 1

Using the content aware tool on different images produces different results. An image with a gradient background such as the sky in this image is quite tricky to work with. Open beach.jpg in Photoshop.

Step 2

We are extracting the person on the left from this photo. Using the Pen Tool, (P) Begin by making a path around the subject. The nice thing about using content aware is that you do not have to be exact when making a selection. In fact, do your best not to cut too close to the subject.

Notice in the image below how far I am drawing the path from the subject. Try to keep this distance all the way around. If you go too close, Content Aware will take pixels from the subject. If you cut too far it will take pixels from the woman on the right.

Step 3

Once you complete the path around the subject, turn it into a selection. This can be done by right clicking on the path and selecting Make Selection.

A dialog box will pop-up, make sure the feathering is set to 0px. Leave all other options as they are. Click OK.

Step 4

Now we have an active selection around our subject. In this step we will make the subject disappear from the image using Content Aware Fill. To do this, go to Edit > Fill.

A dialog box will pop-up, make sure the Content Aware option is selected. Blending mode is set to normal and the opacity is at 100%. Hit OK.

You can cancel the selection at any time by making another selection or just clicking anywhere else on the page with any selection tool.

Step 5

In this step we will remove some of the other artifacts in the image using the same process. The content aware tool did miss a spot where the subject’s foot originally was. To do this, draw a rectangle around the area using the rectangle selection tool. And use the content aware fill as we have done in the previous steps.

Now let’s remove the people towards the right of the image. Create a rectangle selection around them and use the steps we just demonstrated to remove them.

Step 6 (Optional)

Using the Crop Tool (C) lets crop the image so that the focus is drawn to the woman jumping. To do this, just crop out an area of the image that you would like to keep. Beware of the shadow that is left behind from the person that we have removed. You can use the Content Aware feature to remove this shadow but I have decided to crop it out altogether.

Click the checkmark at the top to keep this area. Photoshop will discard the content that is outside of your crop area.

Step 7 (Optional)

In this step we will enhance the photo by giving it a more vibrant look. The colors currently appear somewhat dull. There are many ways to accomplish this but we will use Color Curves. To do this, go to Image > Adjustments > Curves, (Cmd + M). A dialog box will pop-up and we will select each of the channels, R, G, B and work on them separately. Select the Red channel from the dropdown menu.

We are going to make two points on the graph. One in the bottom of the top right square, and one in the top of the bottom left square.

Once you have made these points, make sure you enter the values for each. For the top right point the Output value is 199, and the input value is 185. For the bottom point the values are 56 and 68, respectively. You can play around with these setting and adjust them to whatever you feel is appropriate. Repeat this for each of the colors, Green and Blue.

Final Image

Your image should now look something like the one seen below. As you can see, we have removed the man on her left with very little effort using Photoshop CS5′s new Content Aware Feature.

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Configuring Log Rotation of Apache2 and Other Logs

20/04/2021 Comments off


I went to check out my apache2 logs

ls /var/log/apache2/

and I noticed that they were being automatically rotated (access.log, access.log.1, etc.) and compressed with gzip (access.log.2.gz, etc.). This seems to be the default Ubuntu configuration. I wanted to make find out more, and I found this helpful article about Ubuntu logs, including Apache2 Log info and some basic log rotation info.

After reading through the info, I decided that I wanted to make a few changes. The log rotation happens via the brilliantly named logrotate command. It turns out that logrotate settings kept in 2 places. Lire la suite…

20 Linux System Monitoring Tools Every SysAdmin Should Know

19/04/2021 Comments off

monitoring toolsNeed to monitor Linux server performance? Try these built-in command and a few add-on tools. Most Linux distributions are equipped with tons of monitoring. These tools provide metrics which can be used to get information about system activities. You can use these tools to find the possible causes of a performance problem. The commands discussed below are some of the most basic commands when it comes to system analysis and debugging server issues such as:

  1. Finding out bottlenecks.
  2. Disk (storage) bottlenecks.
  3. CPU and memory bottlenecks.
  4. Network bottlenecks.

#1: top – Process Activity Command

The top program provides a dynamic real-time view of a running system i.e. actual process activity. By default, it displays the most CPU-intensive tasks running on the server and updates the list every five seconds.

top-output-269x300Commonly Used Hot Keys

The top command provides several useful hot keys:

Hot KeyUsage
tDisplays summary information off and on.
mDisplays memory information off and on.
ASorts the display by top consumers of various system resources. Useful for quick identification of performance-hungry tasks on a system.
fEnters an interactive configuration screen for top. Helpful for setting up top for a specific task.
oEnables you to interactively select the ordering within top.
rIssues renice command.
kIssues kill command.
zTurn on or off color/mono

Lire la suite…