30Nov/170

Comparison of administration panels: cPanel vs. Plesk vs. Webmin

We are often asked which panel we would recommend. Since there is a variety of different panels with different functions and focus, we cannot easily answer this question. Currently we offer cPanel, Plesk, LAMP und Webmin, which we will introduce here.

cPanel/WHM

cPanel is a webhosting panel which allows to administrate a great number of users in an easy way and configure the installed services. In order to avoid security breaches many settings are pretty restrictive, which may cause issues due to the demands of your software. In addition, without plugins from external developers, it would not be possible to use nginx as an example. The software cPanel is divided into two parts, the interface for users is called cPanel, the administration interface WHM (WebHostMananger).

The developers provide a really detailed documentation which explains nearly all functions cPanel/WHM provides:

https://documentation.cpanel.net/

If errors occur or special questions appear which are not answered within the documentation, it is always a good possibility to ask for this within the official forum:

https://forums.cpanel.net/

And for those who do not know cPanel/WHM or want to check out what was changed before updating the own installation, a demo and the changelog are available:

https://cpanel.com/demo/
https://documentation.cpanel.net/display/CL/Change+Logs

If you are a new user, you may check out their YouTube channel, too:

https://www.youtube.com/user/cpaneltv

Plesk Onyx

Plesk understands itself as a platform for developers, thus it has a lot of software already installed and software like Docker, Ruby, etc. can be installed with a few clicks. In addition to this, a lot of features can be installed, using free or paid addons, which can be installed with a few clicks, too. Nevertheless, it is even an alternative to start a webhosting. At the moment, three different versions are offered, all details regarding the differences and the official addons can be found within the following document provided by Plesk:

https://www.plesk.com/wp-content/uploads/2017/03/plesk-onyx-licensing-guide.pdf

Plesk provides a detailed documentation, too:

https://docs.plesk.com/en-US/onyx/

In addition, a knowledge base with the most common problems and errors - and corresponding solutions - is provided:

https://support.plesk.com/hc/en-us

Moreover, the developers and community are active within the forum and provide assistance in case of problems:

https://talk.plesk.com/

Webmin

Webmin is no classic interface for webhosting, it is a server administration panel which provides a graphical interface to configure the installed services with the goal making server administration easier. An overview of the supported services can be found within the official documentation:

http://doxfer.webmin.com/Webmin/Webmin_Modules

In addition to the supported modules it is no problem to add additional software via SSH or develop more addons for Webmin to extend the list of services, this is possible due to the fact, that the source code is provided via GitHub:

https://github.com/webmin/webmin

As already mentioned, Webmin is by default no webhosting interface like cPanel or SSH but there was an additional software stack developed which provides the functionality required for webhosting:

https://www.virtualmin.com/

If you only want to use the server as a mail server, cPanel, Plesk and even Virtualmin may be a little bit to heavy, you can think about Webmin, too, since there is an additional addon which provides the basic mail server software:

http://www.usermin.com/usermin.html

LAMP

LAMP has already been offered since a few years and is not a panel like the other ones already mentioned, it is a software stack which contains (Linux,) Apache, MySQL and PHP; this is the basic software to start with your own web presentation. We already published a tutorial about this called "LAMP made easy".

Webmin + LAMP

After we had started offering LAMP, we were often asked why it is not possible to select both Webmin and LAMP. Since we always note down your feedback, we started offering both solutions as one package, so that you can start directly with your webpage after we have sent out the login details to you.

 

Conclusion

As you can see, there are different Panels on offer and the decision, which one to choose, also depends on the chosen operating system: cPanel can only be combined with CentOS, whereas Plesk can also be used with Windows Server. By the way: You can test Plesk one month for free (available for our VPS) and get used to the many functions this panel offers!

7Nov/170

CHIP Hotline-Test 2018: First place for Contabo!

Great news from inside Contabo: The German IT magazine „CHIP“ has thoroughly tested the hotlines of several providers. Among companies from other industries, 14 hosting providers were part of that study, which was conducted in cooperation with the market research experts from the well-known institution “Statista”.

Calling every provider at least 50 times at different points of time, the research team raised different questions and reported several problems. Every call was evaluated based on the following criteria: waiting time, reachability, transparency and especially the general service – on a range of 0 to 100. Our support team fully convinced the researchers, consequently leading to the following result:

Contabo is the overall winner among hosting providers and the only hosting provider in Germany with the top rating “very good”.

CHIP.de reports: “Contabo excels with a record-breaking low waiting time. After an average of 12 seconds, the research team spoke to a member of the customer service. This number can hardly be topped, even across other industries. In addition to that, everything worked smoothly. Hardly any other provider handled their inquiries in such a hassle-free manner, the researchers agreed.”

Overall, we achieved 92.8 out of 100 possible points (second best: 88.9) and CHIP especially praised the short waiting time and the great overall service experience at Contabo.

The complete test report with all details can be found in the CHIP edition 12/2017.

Receiving the award for the first place among 14 big hosting providers is a huge honor for us. In addition to that, we will continue to work hard every day in order to provide each and every one of you, our valued customers, the best possible support in every situation.

You can contact us by phone directly via landline number, without any hotline fees, queues and complex menu selection – on 365 days per year.

26Oct/170

How to manage your websites in Plesk: The WordPress Toolkit

In Plesk Onyx, which we offer for our VPS and dedicated servers, you can comfortably manage your WordPress sites with the extension "WordPress Toolkit". The software enables you to set up a new WordPress site by only a few clicks, it can find already existing WordPress installations on its own and it will show them all in a list. There you can do administrative tasks like updating, installing plugins and much more on all installed WordPress instances at once. Therefore, the extension is very interesting for resellers but also for end users. The WordPress Toolkit is available for all three Plesk Onyx versions at no additional charges, but the range of functions in the Web Admin Edition got reduced in some points. For more information about the differences between the full version and the special Web Admin edition, please take a look on this site: https://www.plesk.com/extensions/wordpress-toolkit.

You can easily check if the extension has already been installed in your Plesk by changing to the following oversight: Server Management > Tools & Settings > Updates and Upgrades > Add/Remove components > Plesk extensions. You should see a green tick next to the extension "WordPress Toolkit". If there is still a red X shown, please use the "Install" function in the drop-down menu. With continue, you will proceed with the installation. You will find the extension afterwards below the menu item "Server Management" in the main menu of Plesk. It is called "Wordpress" there. In case you can not find those menus, you can also use the Plesk search bar. Maybe you are not using the Service Provider view then.

Here you can see a screenshot of the available options. You can increase the size of every image in this tutorial by clicking on it.

You can use those options selectively or on all WordPress instances at once. We will now explain those options from the left to the right.

  • Scan
    There you can search for existing WordPress installations. They will be added to the list below automatically.
  • Check Security
    There you can check your WordPress instances for elementary security problems. You will get a list with points that got checked and possible automatic improvements you can confirm.
  • Plugins
    You will get a collection of the installed plugins and also an update check for those plugins will be performed. You can install and remove plugins for your sites there as well.
  • Themes
    There you can manage your themes and exchange them for multiple WordPress sites at once.
  • Update
    You can update your WordPress installations to the newest version here. Plugins are not touched.
  • Check for Updates
    Here you can check if there are WordPress updates for your sites.
  • Auto-Update
    There you can decide if your WordPress sites should get automatic updates in future.

Additionally to those features, you have the functions Clone and Sync available in every line with an existing WordPress installation.

With Clone you can save a lot of time, if you want to use a fully configured WordPress site as Template. You can also easily change the URL of a WordPress installation this way by deleting the original site afterwards. After clicking on this function, you can do the few required settings and create the target subdomain or select one of the existing domains.

With Sync, you can copy changes to other WordPress installations. This is useful, if you want to test for example new plug-ins on a subdomain before you use them in your public blog. You have the choice between the files, the database or both.

If you want to install a new WordPress for one of your domains, you have to change the menu. Please go to "Hosting Services" and there to "Domains". If it does not exist yet, please add your domain now and open it in the list with all the available domains by clicking on the name of the domain. Next to the usual options, you can see the new one called "Install WordPress", as shown in the image below:

After the installation, you can directly log into the WordPress administration panel from Plesk. If you need the login data or want to change them, you can find this and further options in a dedicated management menu. To open this menu, please click on the name of the WordPress instance left to the direct log in button. We marked this in the picture below:

Sounds great, doesn't it? Give Plesk Onyx a try at Contabo and benefit from our one month for free promotion:

Simply order one of our VPS in combination with Plesk and you will get the edition of your choice one month for free!

18Oct/170

E-mail server in Windows Server, part 2: Security

This is a follow-up to the tutorial How to install an e-mail server in Windows, directed to those who already have an hMailserver and want to increase the security.

Spam protection

To activate the spam protection, please go to Settings >> Anti-spam in the hMailserver Administrator.

In the tab "General" you can leave the settings the way they are, as shown in the image. Of course you can adjust them later according to your needs.

In the second tab "Spam tests" you should select all four spam detection parameters:

- Use SPF (3)
- Check host in the HELO command (2)
- Check that sender has DNS-MX records (2)
- Verify DKIM-Signature header (5)

Malware protection

As already mentioned in the previous tutorial, you have the possibility to use different anti malware software in hMailServer. The most easy solution is to use the free ClamWin anti virus scanner. You can download it there:

https://sourceforge.net/projects/clamwin/

Please follow the installation wizard. Installing the browser extension is not required for your e-mail server. Normally ClamWin will now appear in the Windows system tray and start to update its database once a day. It will also protect your system from malware. You are of course free to change those settings individually in the ClamWin menu. The integration in the hMailServer is easy. Please go to Settings >> Anti-Virus >> ClamWin. The button "autodetect" will find the correct path to your ClamWin anti virus installation and you can finish the setup with "Save".

TLS encryption

To enable your clients to start an encrypted connection to your server, so nobody can steal your data, you have to enable this in your settings first. You will need an SSL certificate to achieve this. If you do not have already one for the host name of your server, you can create a self signed one on your own. Self signed certificates are free. But you will have to add an exception manually each time you set up a new client for your server. Most clients like Thunderbird or Outlook will ask you for that after the credentials got entered and they start the first connection. You can use XCA to create such a certificate:

https://sourceforge.net/projects/xca/

After the software got installed and opened, you have to create a new database on the upper left side. You can choose any name, you do not even have to remember the password. We will need this tool only once to create the new certificate. You can remove it again afterwards.

After the new database got created you can choose the tab "Certificates". In the following menu please choose "New Certificate" on the right side. A new window will open. In this new window please choose the tab "Subject" and add your host name next to "commonName". In our example screenshot this is mail.yourdomain.com. Now please create a key for the certificate by pressing the button "Generate a new key". The options in the window normally will be  inserted correctly per default as shown in the image. You can finish the creation with "create".

The next step is to switch to the tab "Extensions". Enter a date until the certificate will be valid. You can be generous at this point. In our example we set a date in the year 2030 for "Validity not after". With the "OK" button in the bottom right corner you will finally create the certificate.

Now you have to export the certificate and the according key. Please choose in the tab "Certificates" the certificate and click on "Export" on the right side. You can let the path the way it is. In our case it is:

C:\Program Files (x86)\xca\mail.yourdomain.com.crt

In the tab "Private Keys" please do the same for the previously created key. The path should be:

C:\Program Files(x86)\xca\mail.yourdomain.com.pem

Please open the hMailServer Administrator and navigate to Settings >> Advanved >> SSL certificates and click on "Add". Now you have to add the previously exported certificate and key as shown in the image below and save the settings.

For the last step please go to Settings >> Advanced >> TCP/IP ports. There you have to modify the three entries below "0.0.0.0 / 25 / SMTP" as shown in the following images. At "SSL Certificate", please choose your recently created certificate. "0.0.0.0 / 25 / SMTP" has to stay in its original state as the only one. If you change it, your e-mail server will not work properly!

Now you have to open the new ports in your firewall. For that you can edit the rule from the previous tutorial. We called it "Ports for hMailServer" there. Please change the "local ports" from 25, 110, 143, 587 to 25, 465, 993, 995. (Windows Firewall with Advanced Security on Local computer >> Inbound Rules >> Ports for hMailServer >> Protocols and Ports)

The settings for your clients have changed too:

ingoing server:

protocol: IMAP; port: 143; security: SSL/TLS; server: the IP or hostname of your server

outgoing server:

protocol: SMTP; port: 587; security: SSL/TLS; server: the IP or hostname of your server

9Oct/176

How to install an e-mail server in Windows Server

You want to send and receive e-mails with your Windows server and connect to it by using your clients on PC, smartphone or tablet? In this tutorial we will explain how you can setup your own e-mail server on a Windows system with a static public IP. This tutorial will work for our VPS as well as for our dedicated servers. hMailServer is a free open source program, the setup is rather simple and can be done in just a few easy steps. Next to the default features like SMTP, POP3 and IMAP, the software is capable to detect spam and also a free virus protection like ClamWin can be added.

Installation

hMailServer needs NET Framework 3.5. to run correctly. Therefore you should add it to Windows before you install hMailServer. To do so, please open the Server Manager. The next steps will differ a little in the different versions of Windows Server. We will explain it by using the example of Windows Server 2012. Please click on "Manage" on the right upper side and choose "Add Features and Roles". In the window that opens you can click four times on "Next" and leave all the settings the way they are. Now you can choose the features you need to install. You just have to choose the NET Framework 3.5 like shown in the image. With "Next" again, you confirm this selection and "Install" will start the installation. As soon as the process is finished, you can close the window and proceed with the installation of your e-mail server.

Please download the latest version of the software from this site:

https://www.hmailserver.com/download

Please do not choose a version that is still in beta, since it might contain bugs and vulnerabilities. After you received the installation package, you can execute it and accept the terms of service.

You should leave the default installation directory as is and continue with "Next". Now you can choose the required products for installation. You will need the full installation, so please let "Server" and "Administrative Tools" checked and proceed with "Next". For an easy installation, we do recommend to choose "Use built-in database engine" in the next step. In the following window let the name be hMailServer and proceed. hMailServer will need a password for administrative tasks in the future. So please create a password you want to use to protect your service and write it down. The last step will be to start the installation. It should finish without error.

hMailServer Configuration

Please open the hMailServer Administrator. In the first window you have to activate "Automatically connect on Start-up" and click on "Connect".

In the next window, please go to "Domains", choose "Add..." and insert your domain you want to use for sending e-mails.

After the domain got saved, you can add new e-mail addresses in the menu "Accounts".

Now please go to Settings >> Protocols >> SMTP >> Delivery of e-mail. There, please add the local host name of your server that should be used for introducing your server to other e-mail servers. It has to be a valid domain and has to resolve to the IP of your server. So please add an A record to your DNS zone if necessary. You also should set an identical PTR for the IP address of your server. This can be done in the Contabo customer control panel. The host name should consist of three parts. That means it has to be an FQDN and it may not contain too many numbers, since it might seem to be generic. A good name for example might be: "mail.justanexample.com". When you are done, please save your new settings.

Firewall Configuration

The main configuration is done. But you still have to open all used e-mail ports in the firewall to make it work. Please open the Windows Firewall settings and choose "Inbound Rules". On the right side click on "New Rule". A window will open and you have to choose "Port" and click on "Next". In the next window please insert the ports 25, 110, 143 and 587, as shown in the image.

In the following window please choose "Allow The Connection" and after "Next", please check "Domain", "Private" and "Public".

In the last window you can enter a name for the new rule. For example "Ports for hMailServer". Please finish the setup and close the firewall settings.

Now you should add an SPF record to your DNS zone. Many e-mail servers will reject e-mails from your server if it does not exist. Therefore please add this TXT record to your zone:

justanexample.com 86400 in TXT "v=spf1 ip4:1.2.3.4 ~all"

"justanexample.com" has of course to be replaced with your domain and 1.2.3.4 with your IP.

You should also add an MX record to your DNS zone, if it does not exist already. The MX record should look like this:

justanexample.com 86400 in MX 10 "mail.justanexample.com"

The value "mail.justanexample.com" has to be replaced with the the host name you have chosen for your e-mail server.

The basic setup of your e-mail server is now complete. It should be able to send and receive e-mails as soon as the DNS changes are active and you can now connect with any e-mail client like Outlook, Thunderbird or Apple Mail.

Client Configuration

Please use the following settings for your e-mail client.

ingoing server:

protocol: IMAP; port: 143; security: none; server: the IP or host name of your server

outgoing server:

protocol: SMTP; port: 587; security: none; server: the IP or host name of your server

Security

If you want to do some optimizations to the server security like transport encryption, spam checks and malware protection, please take a look at our second tutorial: E-mail server in Windows Server, part 2: Security.

11Sep/172

Dedicated Server: 10 Gbit/s-port available

From now on and by your request, we offer you an internet connection of 10 Gbit/s (for every server) for our dedicated servers Dual Xeon and 10-Core.

With this upgrade, your server will receive an Internet uplink of 10 Gbit/s (=10.000 Mbit/s) instead of the regular port. We use a high-quality network card from Intel in order to provide you with that bandwidth.

This upgrade is especially suited for customers who generate traffic peaks, which exceed the standard connection of 1 Gbit/s.

You can add the 10 Gibt/s-port for 99.99 € /month plus a one-time setup fee in the same amount. New customers can select the upgrade during the order process of the respective dedicated server on Contabo.com.

Do you already have a dedicated server and would like to add this upgrade? No problem at Contabo! Existing customers can order this upgrade at any time. Please contact our customer support department and specify your wish.

24Aug/170

No space left on your HDD/SSD? Find big files and remove them!

It does not matter if you do website hosting, provide a gameserver or use other services, if you have no space left on your HDD/SSD problems will occur. Your websites might not be reachable anymore, your players cannot connect to your gameserver or all other services will not start.

To avoid this it is necessary to find big files on your system and to get rid of them. Today we will show you how to do this.

Linux:

1. Connect to your server using SSH

2. Execute the following code:

# Change into root folder
cd /

# Find the top 10 files. This may take a while:
find -type f -exec du -Sh {} + | sort -rh | head -n 10

Once finished, a list of the ten largest files will be displayed. Normally these files might be old downloads or big log files. Files that are no longer used can be deleted, of course. Before deleting log files you should check them for errors you can solve so that the issue will be permanently fixed.

3. Using the command below you can remove files

rm <path_to_file>

Windows:

In Windows you might not find big log files but forgotten downloads. To find them the following freeware is perfect:

http://www.jam-software.de/treesize_free/?language=EN

Once you downloaded and executed the software you can start scanning a partition. A list of all files will be displayed. Please make sure not to delete Windows system files 😉 .

Posted by: Mike | Tagged as: , , , , No Comments
11Aug/172

Overview of available RAID levels

With this tutorial we will explain certain types of RAID levels to you.
Some of you might have already experienced a loss of data, no matter if it was an SD card holding some vacation photos or a hard disk holding important files. Losing data can be very costly if you try to restore them by some specialist. An expert is needed and the procedure takes a lot of time, the easiest way to avoid those costs is simply to avoid any data loss in the first place.

This overview is not relevant for any VPS, your VPS systems are already running safe on a RAID system monitored by experienced technicians.

Creating backups is still very important, a RAID does not replace any backup!

You can find further instructions within the following tutorial: Data loss and how to avoid it

There are some points which you should think about first, there are several results depending on your requirements.

  1. How important is the performance?
  2. How much data security should be provided by the RAID?
  3. Are system resources available to manage the RAID, such as CPU and RAM

Depending on the results of the above questions and your budget, there are several options available:
A hardware RAID is always more expensive but provides the best performance and security (if combined with a battery backup unit).
A software RAID is the easiest way to go for a RAID, it is able to handle almost any type of RAID and can be set up within a few minutes.

An overview of available RAID levels is shown below:


RAID 0

The RAID 0 provides increased write and read performance, the data will be distributed to at least two disks. Since there is no redundancy all data will be lost in case one disk fails.

  • At least two hard disks are needed
  • No disk redundancy at all
  • Maximum (complete) storage capacity available
  • Improved read and write performance


RAID 1

The RAID 1 provides increased read performance (depending on the software/hardware controller used), all data will be mirrored to a second disk. There is also a RAID 1E available - in that case all data will be mirrored to additional disks too.

  • At least two hard disks are needed
  • n-1 disks can fail
  • 1/n of storage available (n = number of disks, with two disks = > 1/2 of total storage)
  • Improved read performance


RAID 5

The RAID 5 provides increased write and read performance, the data is written to at least two disks, an additional disk is always used for storing parity data. The parity data has to be calculated for every write - so for very write intensive applications the RAID 5 requires a lot of performance due to the necessary calculations.

  • At least three hard disks are needed
  • One disk can fail
  • n-1/n of storage available (n = number of disks, with three disks = > 2/3 of total storage)
  • Improved read and write performance
  • Requires a lot of CPU time


RAID 6

The RAID 6 provides increased read performance, the data is written to at least two disks, two additional disks are always used for storing parity data. The parity data has to be calculated for every write - so for very write intensive applications the RAID 6 requires a lot of performance due to the necessary calculations. As there are two parity bits saved on the disks, the needed CPU time is very high.

  • At least four hard disks are needed
  • Two disks can fail simultaneously
  • n-2/n of storage available (n = number of disks, with two disks = > 2/4 (half) of total storage)
  • Improved read performance
  • Requires the most CPU time


RAID 01

A RAID 01 is a combination of two or more volume groups. Each volume group is configured to have a RAID 0, those volume groups are mirrored in a RAID 1. With a total number of four disks one entire volume group can fail with both disks and no data will be lost.

  • At least four hard disks are needed
  • Two disks can fail simultaneously if they belong to the same logical volume group
  • Half of total storage capacity is available
  • Improved read and write performance


RAID 10

A RAID 10 is a combination of two or more volume groups. Each volume group is configured to have a RAID 1, those volume groups are striped in a RAID 0. With a total number of four disks, two disks can fail simultaneously and no data will be lost - the failed disks must not belong to the same volume group.

  • At least four hard disks are needed
  • Two disks can fail simultaneously if they do not belong to the same logical volume group
  • Half of total storage capacity is available
  • Improved read and write performance


 

The difference between RAID 01 and RAID 10 is only visible with six or more disks, if you have six disks a RAID 10 will provide a higher calculated security rate. We do recommend using a RAID 10 instead of using a RAID 01 even if you do only have four disks. Some RAID controllers do not even support a RAID 01 anymore. RAID 5 and RAID 6 require the highest CPU time since a checksum has to be calculated on every writing process to the disk. Only a few enterprise RAID controllers do support RAID 5 and RAID 6, due to the need of calculating checksums the writing speed might suffer which might then cause problems when using write intensive applications.

For our dedicated servers it is always possible to order additional hard disks or RAID controllers, current prices can be found on our web site. If you need a special configuration, please contact our support team any day between 8 am and 11 pm (German timezone, UTC+2).

Posted by: Gianni-Donato | Tagged as: , , , , , 2 Comments
3Aug/170

Available now: Fedora 26 and Suse Leap 42.3

As of today, we offer you the brand new Fedora 26, it replaces the previous version 25. Additionally, Suse Leap was updated as well and the latest version 42.3 is available at Contabo!

Both operating systems can be combined with the Software RAID 1 and Webmin. In addition, Fedora 26 can be installed via VNC as well.

Being an existing customer, you can easily upgrade to the new versions through your customer control panel.

We always offer you a large selection of Linux distributions (as well as Windows Server 2012 and 2016). Just click on "Customize & Order" below your desired (virtual) server model in order to get a detailed overview and select the operating system of your choice!

Please note: You can find further information and a product overview on our website!

Posted by: Markus | Tagged as: , , , , , No Comments
19Jul/170

Analysing log files in Windows and Linux

Everyone knows the scenario, you want to analyze an issue of your server or local computer but where to find all those log files?

In the following tutorial we are going to analyze specific log files in Linux and logs in the Windows Event Viewer. An additional chapter will go through the log analysis via Systemd.

Linux log files

Unfortunately, it is quite different from distribution to distribution, which information can be extracted from specific log files. In the following we will analyze the log file structure of Debian 8 and CentOS 7.2. The first location to look for log files should always be /var/log/. Depending on their configuration, Apache, Nginx or similar applications write log files to this folder too. System log specifications and locations can be found in the file /etc/rsyslog.conf.

Debian 8:

  • /var/log/auth.log

Logs of successful and failed authentications to your system can be found in this log file. It is also logged when a user invokes commands via sudo.

  • /var/log/messages

This file contains log entries of general system information, amongst others, you will also find the system upstart logs.

  • /var/log/dmesg or dmesg

The kernel ring buffer can be read with dmesg. You will find information about the system upstart, runtime kernel module messages and many further messages according to the hard and software of your system. By default, dmesg shows the full ring buffer. However, the output can be customized by adding specific parameters. A thorough documentation can be found on the manual page (man dmesg).

  • /var/log/syslog

This is one of the most important log files in general. Every Linux process is free to log to the syslog by implementing the syslog interface. It also logs the system upstart and executed cron-jobs.

CentOS 7.2:

As the log file structure is quite similar to the one of Debian 8, we will just mention the differences.

  • /var/log/secure

This log file is the equivalent to /var/log/auth.log in Debian systems. All kind of authentications are logged here.

  • /var/log/messages

There is no separation of /var/log/messages and /var/log/syslog in CentOS, all system logs of processes which implement the syslog interface can be found here.

  • /var/log/cron

Cron specific log files are not part of the syslog as in Debian. They can be found in the above mentioned file.

 

Log analysis via Systemd

Systemd is basically the standard Init system of nearly all major Linux distributions today. Since at least April 2015, when Debian and Ubuntu switched to Systemd, every Linux administrator or user has been in touch with Systemd. As Systemd is a complex system, we will only take a look into the log analysis functionality provided. Every process in Systemd is identified as a unit. All active units can be shown via the following command:

systemctl list-units

When appending the parameter --all, this command also shows all inactive units.

Logs being created by Systemd are managed in the so called Journal. These logs can be accessed via the journalctl binary. If journalctl is called without any parameter, it will print out the whole Journal. However, it is also possible to output the log entries of specific units only. In the following example, we are going to analyze the log files of the Apache web server.

journalctl -u httpd

It is also possible to restrict the output with the parameters --since and --until.

journalctl -u httpd --since "2016-11-01 20:00:00" --until "2016-11-03 20:00:00"

The above command will output the Apache log entries between 2016-11-01 20:00:00 and 2016-11-03 20:00:00. It is also possible to use keywords like "today" or "yesterday".

You can also output the log files of more than one unit at the same time. In the following example we will output all Apache and Nginx log entries which have been logged since yesterday.

journalctl -u httpd -u nginx --since yesterday

If the parameter -f is used, all desired log entries are shown in real time.

The above was only a slight view into the possibilities of journalctl, there are several other useful features which are described on the manual page (man journalctl).

 

Log analysis via Windows Event Viewer

Windows Event Viewer Overview

In the above picture in the left navigation you can see the entry "Windows Logs". The following entries are most important.

  • Application

This entry will show the events of locally installed applications.

  • Security

Here you can see successful and failed login attempts.

  • System

This entry logs operating system internal events and errors.

Via the entry "Custom Views" -> "Server Roles" -> "Remote Desktop Services" you can see RDP related events and errors.

Potential hardware issues can be identified via "Application and Service Logs" -> "Hardware Events".

Useful for error analysis can also be the overview which can be seen via "Overview and Summary" -> "Summary of Administrative Events", it provides a summarized overview of the system status in general.