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How to Restrict IP Addresses from Accessing your Web Server using .htaccess

17/04/2019 Aucun commentaire

If you are running the Apache Web Server or your web hosting provider running Apache based web server, you can use .htaccess configuration file to restrict access to your website. This could be a very important issue from security stand point of view especially if your server is being attacked or hacked from any specific or range of IP addresses.

Now, restricting access method works in two ways. First, you can restrict access to certain IP addresses and allow others. Second, you can restrict access to everyone but few IP addresses only. On this post, I will focus on both method and will try to explain as much as I can.

Restrict Certain IP Addresses

If you want to restrict specific IP addresses from accessing your site, you can use the following lines on your .htaccess file.

order deny,allow
deny from 123.4.5.6
deny from 654.3.2.1
allow from all

These lines above will block “123.4.5.6” and “654.3.2.1” IP addresses from accessing your site. You can add as many IP addresses as you want on this “deny from” list. One interesting fact is, Apache web server gives you lot more flexibility in terms of blocking IP addresses. Take a look at the following lines.

order deny,allow
deny from 123.4.5.
allow from all

If you observe it carefully, you will see that the fourth set of digit is missing on this IP address. It means, if any IP address that matches the first three set of digits will be blocked. So basically anyone with IP address like “123.4.5.1” or “123.4.5.244” won’t be able to access your site as in both IP address matches with the first three (123.4.5.) sets of digits blocked by the Apache web server.

Allow Specific IP Addresses

Think of about a site that you built for a very specific purpose and for very few people, where you do not want everyone to show up. Apache allows you to do that as well.

For an example, lets assume that you built a site that you want one of your friend to be able to access and his IP address is “123.4.5.12”. Simply write the following line on your .htaccess file and you are good to go.

order allow,deny
allow from 123.4.5.12
deny from all

In this case Apache will block all IP addresses except your friends IP address. This is as simple as it can get and I hope you got the basic idea.

Note: On all of my example I used either “allow from all” or “deny from all” at the bottom, this is very important. You must declare either one of these line based on your requirement or things might get little more complicated.

Also remember that all blocked IP addresses would be forwarded or shown an “403 Forbidden” error message. You can definitely customize this message as well but that’s something I will talk about in another post.

Source: iftekhar.net

Categories: Logiciel Tags: , , ,

How to configure virtual hosts in Apache HTTP server

12/04/2019 Aucun commentaire

Source: Xmodulo

Virtual hosting refers to the technique that allows a physical server to host more than one website domain (e.g., site1.com, site2.com). Virtual hosting is prevalent in shared web hosting environments, where typically hundreds or more of websites or blogs are packed on a single dedicated server to amortize server maintenance cost.

You are not a web hosting company? Sure, virtual hosting can still be useful to you. For example, you can place multiple websites of yours on one VPS that you rent out, saving on your VPS cost. To serve multiple domains on a VPS, you just need to configure as many virtual hosts on its web server, and point the domains to the static IP address of your VPS.

Due to its usefulness, virtual hosting is supported by all modern web server software such as Apache, Nginx, Lighttpd, IIS. In this tutorial, I will demonstrate how to create and enable virtual hosts in Apache HTTP server under Linux environment. There is slight difference in the configuration between Debian-based and Red Hat-based systems. I will highlight the difference along the way.

Before I start, I assume that Apache HTTP server is already installed on your Linux server. If you haven’t, refer to our tutorials for Debian or Red Hat based systems, and install Apache server before proceeding.

As an exercise, let’s create a virtual host for domain abc.com on Apache web server.

Step One: Create Document Root Directory for Abc.com Domain

Start by creating a directory which will hold the web pages for abc.com. This directory is known as « document root » for the domain. Following the common practice, let’s organize all document root directories under /var/www, and name them after the corresponding domains. Also, create a dedicated log directory for abc.com under /var/log.

$ sudo mkdir /var/www/abc.com
$ sudo mkdir /var/log/apache2/abc.com (Debian, Ubuntu, Mint)
$ sudo mkdir /var/log/httpd/abc.com (Fedora, CentOS, RHEL)

Create a test webpage for the domain:

$ sudo vi /var/www/abc.com/index.html
<html>
  <head>
    <title>Welcome to Abc.com</title>
  </head>
  <body>
    <h1>Sample page</h1>
    This page is powered by Apache Virtual Host!
  </body>
</html>

Change the ownership of the document root directory to the user that Apache web server runs as.

On Debian, Ubuntu or Linux:

$ sudo chown -R www-data:www-data /var/www/abc.com

On Fedora, CentOS or RHEL:

$ sudo chown -R apache:apache /var/www/abc.com

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Categories: Logiciel Tags: ,

How to live stream video from webcam on Linux

11/04/2019 Aucun commentaire

Source: Xmodulo

Have you ever wanted to live stream a video feed from your webcam for someone else? You could use any existing video chat software such as Skype, Google+ Hangouts. However, if you do not want to rely on any third-party streaming infrastructure, you can set up your own webcam streaming server in house.

In this tutorial, I will describe how to live stream video from webcam by using VLC. VLC is an open-source, cross platform media player which can handle virtually all video and audio formats. VLC can also run as a streaming server supporting various streaming protocol such as RTP, HTTP, RTSP, etc.

Before attempting to set up webcam streaming on your own, you need to understand the huge potential security risk of streaming a webcam over the Internet. Anyone can tap into your streaming feed unless you properly access control the streaming server, and encrypt the streaming traffic. I’ll briefly mention several security protections against threats towards the end of the tutorial.

Install VLC on Linux

Before setting up a streaming server with VLC, install VLC first.

To install VLC on Debian, Ubuntu or Linux Mint:

$ sudo apt-get install vlc

To install VLC on Fedora, first enable RPM Fusion’s free repository, and then run:

$ sudo yum install vlc

To install VLC on CentOS or RHEL 6, first set up EPEL repository, and then use the following commands:

$ cd /etc/yum.repos.d/
$ sudo wget http://pkgrepo.linuxtech.net/el6/release/linuxtech.repo
$ sudo yum install vlc

Verify Webcam Device on VLC

Next, verify whether a webcam device is successfully detected on your Linux system and VLC.

To do so, first find out the device name of your webcam with the following command. In this example, the device name of the webcam is /dev/video0.

$ ls /dev/video*
/dev/video0

Now use the following command to test video from your webcam. Replace « video0 » with your own device name.

$ vlc v4l2:///dev/video0

If your webcam is successfully detected by VLC, you should see a video stream of yourself.

Configure Webcam Streaming on VLC

Assuming that your webcam is successfully recognized by VLC, I am going to show how to configure webcam streaming. In this setup, webcam is streamed over HTTP in WMV format.

To configure VLC for webcam streaming, first launch VLC.

$ vlc

Choose « Streaming » from VLC menu.

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On the screen, choose webcam/audio device name (e.g., /dev/video0 for webcam, and hw:0,0 for audio). Click on the checkbox of « Show more options ». Make a note of value strings in « MRL » and « Edit Options » fields. We will use these strings later in the tutorial. Click on « Stream » button at the bottom.

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Categories: Logiciel Tags:

How to analyze and view Apache web server logs interactively on Linux

10/04/2019 Aucun commentaire

analyze apache logsWhether you are in the web hosting business, or run a few web sites on a VPS yourself, chances are you want to display visitor statistics such as top visitors, requested files (dynamic or static), used bandwidth, client browsers, and referring sites, and so forth.

GoAccess is a command-line log analyzer and interactive viewer for Apache or Nginx web server. With this tool, you will not only be able to browse the data mentioned earlier, but also parse the web server logs to dig for further data as well – and all of this within a terminal window in real time. Since as of today most web servers use either a Debian derivative or a Red Hat based distribution as the underlying operating system, I will show you how to install and use GoAccess in Debian and CentOS.

Installing GoAccess on Linux

In Debian, Ubuntu and derivatives, run the following command to install GoAccess:

# aptitude install goaccess

In CentOS, you’ll need to enable the EPEL repository and then:

# yum install goaccess

In Fedora, simply use yum command:

# yum install goaccess

If you want to install GoAccess from the source to enable further options (such as GeoIP location), install required dependencies for your operating system, and then follow these steps:

# wget http://tar.goaccess.io/goaccess-0.8.5.tar.gz
# tar -xzvf goaccess-0.8.5.tar.gz
# cd goaccess-0.8.5/
# ./configure --enable-geoip
# make
# make install

That will install version 0.8.5, but you can always verify what is the latest version in the Downloads page of the project’s web site.

Since GoAccess does not require any further configurations, once it’s installed you are ready to go.

Running GoAccess

To start using GoAccess, just run it against your Apache access log.

For Debian and derivatives:

# goaccess -f /var/log/apache2/access.log

For Red Hat based distros:

# goaccess -f /var/log/httpd/access_log

When you first launch GoAccess, you will be presented with the following screen to choose the date and log format. As explained, you can toggle between options using the spacebar and proceed with F10. As for the date and log formats, you may want to refer to the Apache documentation if you need to refresh your memory.

In this case, Choose Common Log Format (CLF):

15868350373_30c16d7c30

and then press F10. You will be presented with the statistics screen. For the sake of brevity, only the header, which shows the summary of the log file, is shown in the next image:

16486742901_7a35b5df69_b

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What are good open-source log monitoring tools on Linux ?

05/04/2019 Aucun commentaire


In an operating system, logs are all about keeping track of events, be it critical system errors, resource usage warnings, transaction history, application status, or user activities. These logs, which are stored as (text or binary) files in the system, are useful for system auditing, debugging and maintenance. However, with so many different system entities generating log files, and even at growing rate, the challenge as a system admin is to how to « consume » these log files effectively.

That’s when log monitoring tools come into the picture, which streamline the often laborious process of collecting, parsing and analyzing log files, as well as alerting system admins for any interesting events. These tools are designed from ground up focused on log monitoring, so they offer many attractive features, such as scalable log aggregation and filtering, human-readable display, event correlation, visual or email notification, flexible log retention policy, and so on.

In this post, I am going to introduce a list of popular open-source log monitoring software for Linux, ranging from simple log file viewers to full-blown log monitoring frameworks.

Log Aggregation and Filtering

Log monitoring would not be possible without efficient and scalable mechanisms to collect and pre-process log files. Tools in this category focus on shipping, collecting, filtering, indexing and storing log files, so that they can be further analyzed and visualized in subsequent monitoring pipelines.

1. rsyslog: an open-source log collector server which can filter and consolidate log data (based on syslog protocol) from different hosts and devices in the network. rsyslog can be configured as a server or a client, where the former plays the role of a log collector and the latter runs as a log sender.

2. syslog-ng: another open-source implementation of the syslog protocol with more advanced and user-friendly features such as content-based filtering, easier-to-understand config format, and real-time event correlation.

3. systemd journal: systemd journal can be configured for remote journal logging, where locally logged events are forwarded to a remote server over HTTP. In this setup, systemd-journal-upload on a client host serializes and forwards journal messages to systemd-journal-remote running on a remote collector server.

4. logstash: an open-source tool that collects, parses, and stores log files for offline search and analysis. logstash can run in various pipelines due to many plugins supporting different input/output interfaces, decoding/encoding, and filtering rules. Input plugins allows logstash to gather log files from different sources and protocols (e.g., files, S3, RabbitMQ, syslog, collectd, TCP/UDP sockets). Filter/codec plugins are used to parse, convert, modify and add metadata to log files. Output plugins pass processed log files to various target storages (e.g., file, Google cloud storage, Nagios, S3, Zabbix).

5. collectd: a daemon service which gathers various system-level statistics, and stores them for historical analysis or real-time graphing. Similar to logstash, collectd is an extensible architecture, where you can enable various input/output plugins to change its collection behaviors. For log collection, collectd can leverage LogFile and Network plugins to aggregate remote log files.

6. Logster: an open-source utility for parsing log files for any interesting data, and aggregating extracted data into metrics for subsequent reporting and graphing pipelines.

7. Fluentd: a unified log aggregation layer which allows in-stream processing for a variety of streaming data and log files. It comes with a huge plugin ecosystem with more than 300 plugins to support various input sources and output interfaces.

8. Nxlog: a unified log collector and forwarder which supports a variety of log sources, formats and protocols. Advanced features include multi-threaded log collection and processing, message buffering and prioritization, built-in log rotation, and TLS/SSL transport.

9. Scribe:: a scalable log collector server developed by Facebook. Scribe can aggregate log data which is streamed in real time from a large number of clients. It uses Apache Thrift for protocol encoding, so its interface is compatible with pretty much any languages. While a proven solution, Scribe is not something you can deploy quickly as a turnkey. Also, note that Scribe is no longer updated and maintained.

10. Flume: a highly scalable and reliable service to transport and collect large volumes of streaming log data from any clients, and store them in backend storage such as Apache Hadoops’ HDFS.

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