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How To Setup Monkersolver On A Debian 9 (Linux) Server Using Contabo

How to Setup Monkersolver on a Debian 9 (Linux) Server using Contabo

Disclaimer: This guide is no longer up-to-date. Please find our updated guide here.

In this guide I am going to show you how to setup Monkersolver on a Debian 9 Linux server with Contabo.

Why use Linux?

You might ask yourself why you would want to go through the trouble of running Linux on a server for running Monkersolver. There are various reasons why you might want to do this, but the main advantage to running Linux on a server is cost reduction. With cloud computing companies such as Google and Amazon, the licensing fee for running Windows can cost over 4 USD per hour.

Google’s GCP OS Cost Estimate for 1 Month Using an n1-megamem-96 Instance

This is one of the most expensive use cases I could find, but it’s relevant if for example you want to test a setup before renting a large server for one or more months. Another common use case would be with a dedicated monthly rental where say a flat fee of 50 USD is applied for a Windows Server license. This might seem manageable, but it also equates to 600 USD per year in licensing fees that could have been avoided.
Additionally, being able to run Linux will save you money on your own builds, as a Windows license for personal use can cost 100 USD or more.

Where to Start?

For working with solvers and for use cases that require 256 GB RAM or less, I would recommend Contabo’s 10-core dedicated server (256 GB ECC RAM) because of the value at this price point. These can be upgraded to up to 20-cores (40 threads). I would recommend taking the upgrade as it’s relatively inexpensive and at the end of the day will save time in computing which more than makes up for the additional cost. A lot of the steps in this guide will also work with other cloud server service providers, but for the sake of simplicity, I will show the use case with Contabo.


Under ‘Dedicated Server 10-Core’, click on the ‘Customize & ORDER’ button. This will redirect you to a page where you can select the configuration of your server.


On the next page, you want to select ‘+ Intel Xeon E5 2630v4 (10 x 2.20 GHz)’ to get the upgrade to 20 cores.



In the next configuration section ‘Hard disks’ there are several viable options. For Monkersolver, disk speed only matters for loading and saving files, however this can actually take quite some time given the size of some of the solutions, so you want to use a fast drive. I would recommend selecting a regular SSD. 500 GB should be plenty for working with compressed solutions, and I would recommend regular backups to a cloud storage solution as opposed to paying for a lot of unused space.


In the final step of our configuration, you want to select ‘Debian 9’ as your operating system. Other versions of Linux would likely also work, but I’ve done the most testing under Debian 9 for Monkersolver, and so I would simply recommend that as an option. If you happen to be familiar with Ubuntu, you can also try Ubuntu. Ubuntu is a Debian based Linux distribution and so a lot of the following setup will be similar if not the same.

The remaining configuration options can be left as is and you can proceed by clicking the ‘Order now’ button.

Connecting to the server

After Contabo receives your payment, and after a short processing period, they will send you an email with your login data for the server.

Under Linux you can now use the command ‘ssh’ with your user name and password to connect to the server (e.g. ssh Under Windows you can use the program PuTTY to connect to your server using your ip address and the ssh port (e.g. If you are using Mac OS, you can use the built-in terminal. Once you have connected to your server, you will be prompted for your password to complete the login process.

Installing VNC Server to obtain a Graphical User Interface

Monkersolver does not support command line interface (CLI) input at this point in time, and so you will require a graphical user interface (GUI) to interact with Monkersolver. So in order to have a GUI, we will need to install VNC server on our server. The following commands will help you set this up (hit enter after every command).

First we need to update the packages lists on our server:

apt-get update

Upgrade the packages on the package list:

apt-get -y upgrade

For our VNC server we will use ‘tightvncserver’, we will also install the XFCE desktop environment (DE) with some customizations. When prompted, type ‘y’ and press the ‘ENTER’ key:

apt-get install xfce4 xfce4-goodies gnome-icon-theme tightvncserver

You’re going to need a browser, as this setup doesn’t come with one out of the box. My personal preference is Chromium, but you could also use Chrome or Firefox for example:

apt-get install chromium

Later on we are going to make use of 7-zip:

apt-get install p7zip-full

We will also need to install the latest Java Runtime Environment (JRE) in order to run Monkersolver:

apt-get install default-jre

Setting up a VNC User

For security purposes, it is recommended to set up a separate account for running the VNC server using ‘sudo’, a program that restricts the privileges of it’s users.

Add the user vnc:

 adduser vnc

Choose a password, and skip all other questions by hitting the ‘ENTER’ key.

Install ‘sudo’:

 apt-get install sudo

Add the user vnc to the sudo group. This will allow it to execute root commands:

 gpasswd -a vnc sudo

Now select the vnc user. You will need to use the vnc account every time you want to start or stop the vncserver:

 su - vnc

Start the VNC Server

From the vnc account start the server:

 vncserver -geometry 1920x1080

Here I am using the ‘-geometry’ option to specify the size of the output window on the machine from which I am viewing. You can set this to whichever resolution works best for you, 1920×1080 is for a 1080p or FHD monitor. If you do not use the ‘-geometry’ option, the server will output at it’s default of 800×600.

The first time you start the server, you will be asked to enter a password for connections to the server. You will need this password anytime you want to connect to your server, so keep that in mind for future use. The password length needs to be between 6-8 characters long. Optionally you can also set a password for a view-only account.

After you hit enter and choose your password, you will receive output with your display number:

'xauth: file /home/vnc/.Xauthority does not exist
New 'X' desktop is vnc:1

Creating default startup script /home/vnc/.vnc/xstartup
Starting applications specified in /home/vnc/.vnc/xstartup
Log file is /home/vnc/.vnc/vnc:1.log'

The display number correlates to the number at the end of the VNC port, so for display 1, the corresponding port will be 5901, for 2 5902 etc.

If you want to stop the vnc server:

vncserver -kill :1

Where ‘:1’ refers to the display you are trying to stop. To stop the server on port 5902 you will need to use the command:

vncserver -kill :2

Connecting to your VNC Server

In order to connect to the GUI of your server, you are going to need a viewer. There are different programs you can use for this. On Windows, you can use UltraVNC.

In the field ‘VNC Server’ simply enter your server’s ip address and the port on which you have started your VNC server. For example: Hit ‘Connect’, next you should be prompted to input your server password. Now you should see your Debian desktop which should look something like this:

Installing Monkersolver

In order to install Monkersolver on Linux, you will need the installation file for Mac OS (.dmg). Typically this file we be placed in your download folder if you’ve downloaded it through your browser.

Open the terminal. In the XFCE DE 4.x, this can be found in the dock at the bottom of the screen (black box) or from the drop-down menu.

Once you have opened the terminal, navigate to the file in your download folder:

cd /home/vnc/Downloads/

Now using 7-zip we are going to extract our .dmg file containing the Monkersolver files.

7z x monkersolver-setup.dmg

You may need to replace the file name with whatever the name of your file is. This will create a folder with all the contents of your .dmg file extracted. The name of the folder will share the name of the .dmg file.

Using the graphical interface, navigate to your ‘Downloads’ folder. You should see the folder ‘monkersolver-setup’. Double-click on the folder. Inside the folder, right-click on the file labelled ‘’. Select ‘Properties’ under the ‘Permissions’ tab, tick the box ‘Allow this file tun run as a program’. Close the window.

Return to the terminal window and navigate to the extracted folder using the following command:

cd /home/vnc/Downloads/monkersolver-setup

Start Monkersolver:


And that’s it! Now you have Monkersolver up and running on your server.

If you would like to see more Linux related content, please post your suggestions in the comment section below, and subscribe to our blog for more updates in the future.

2018 Update

It is strongly recommended that you restrict access to your server by following the steps in this guide in order to prevent bots from putting your server out of comission.

2019 Update

We have now released an updated version of this guide which you can find here.

Other related articles:

How to Enable Copy-Paste on your Server

This Post Has 26 Comments
  1. Hi.

    Thanks for the guide. Excellent article. I installed Monkersolver on a Debian as written in this article. Everything worked fine, but a couple of days later when I launched the VNC Viewer, I received the message “Too many authentication failures” and I couldn’t connect to my server.

    I tried to stop (vncserver -kill :1) and start server. After that I could connect to the server but Monkersolver was not running and I need to start Monkersolver one more time.

    Now again I recieve the same message “Too many authentication failures” and I can not connect to my server.

    How can I connect to the server?

    1. Thank you for your comment Dima. I believe the “Too many authentication failures” is caused by bots that crawl the internet looking for vulnerable servers. When they try to brute force themselves into a server, the server closes itself off to protect itself. One solution to this is to restrict the amount of accepted IP addresses using the IP tables under Linux. This way whenever an IP address that doesn’t match the list tries to connect to the server, it will be rejected immediately and not be able to trigger a lock-down of the server.

      You will need to connect to your server using SSH (for example using Putty). Once connected, you will need to enter the following commands as root user in order to configure the IP tables:

      sudo iptables -F INPUT && iptables -I INPUT -p tcp -s –dport 5901 -j ACCEPT && iptables -A INPUT -p tcp -s –dport 5901 -j DROP

      Replace the x’s with the IP address you would like to allow to connect to your server. You can find this out by simply typing ‘my ip’ into Google. You then need to manually kill the current vnc process and restart it, in order to be able to access your server again. Any unsaved data will be lost unfortunately.
      You can use the command ‘pgrep vnc’ (without brackets) to find the process id of vnc on your server. You then need to kill it using the command ‘kill pid’. Replace ‘pid’ with the id that was output by the pgrep command. Once the process has been killed, switch to the vnc account using ‘su – vnc’. Then you can restart vnc using ‘vncserver -geometry 1920×1080’ (or whatever resolution you prefer). Now you can connect to your server using only the restricted ip address you specified.

      I hope this helps you. There will be a more detailed guide in the next 1-2 days showing these steps in more detail, but that is the process you need to use to get it back up and running again and to prevent this from happening in the future.

      1. when I tried this command line: “sudo iptables -F INPUT && iptables -I INPUT -p tcp -s –dport 5901 -j ACCEPT && iptables -A INPUT -p tcp -s –dport 5901 -j DROP” I got an error message saying bad argument 5901. I did replace the xx with my own ip.

        1. Try separating the commands. Hit the enter key after every command (minus the brackets):

          ‘sudo iptables -F INPUT’
          ‘iptables -I INPUT -p tcp -s –dport 5901 -j ACCEPT’
          ‘iptables -A INPUT -p tcp -s –dport 5901 -j DROP’

          1. Manged to get the command line go through with –dport instead of -dport. Hopefully this will do the trick.Thanks a lot!

  2. Thanks for the guide, I got it up running in no time.

    I have one question.
    How to I get copy-past to work from my windows 10 station?
    I am using everything exactly like in your guide.

    1. Thank you for your comment. I have a solution to resolving copy-paste with this configuration, however it’s easier if I post the solution in a separate blog post. I will post the link to the article once it’s ready.

  3. I have to 40 thread contabo server, how do I change the default thread setting?
    It starts with 16 threads by default and when I do scripting ir runs with 16 and not the full 40…

    1. Before you run your script, go to the ‘Settings’ tab and set ‘Threads’ under ‘General’ to 40. Alternatively, in the ‘Solve’ tab you can manually adjust threads by using the ‘+’ and ‘-‘ symbols.

  4. Thank you one more time for your help. Monkersolver works perfectly. Is it possible to setup MonkerViewer on the same server (Debian 9 Linux)?

    1. Hi Dima. Yes, it is possible to run MonkerViewer on Linux as well. Using the graphical user interface, navigate to your ‘monkersolver-setup’ folder. Locate the file named ‘’ and right-click copy and paste it to the ‘monkersolver-setup’ folder. You should now have a file named ‘start2 (copy).sh’. I would recommend renaming this file to something like ‘’. Now double-click on the newly created file. This should open the file in a text editor. In the last line of the file you should find the name ‘MonkerSolver.jar’. Simply change this to ‘MonkerViewer.jar’. Now hit the save button. Now, using the terminal, navigate to your monkersolver-setup folder, and simply execute the file using the ‘./’ command, so for example ‘./’ if you use my name suggestion. This should launch MonkerViewer for you. Let me know if you run into any trouble with this.

  5. Hey,thanks for the guide,it’s very helpful.
    Can you please write a guide about how to setup PIOsolver on Debian 9?

    1. Hi Jack. PioSOLVER does not natively support Linux the way that Monkersolver does. It might still be possible to run PioSOLVER on Linux without a Windows license, but it might not be very practical to do so. I will keep this in mind however for future article ideas.

  6. Hey,how can I edit monkersolver.lrj file as I need to give monker more memory?it’s in the monkersolver folder on windows,but I can’t find it on Debian 9.

    1. The name of the file in question is It is located in your Monkersolver folder. You will need to right-click the file and then select ‘Open With Mousepad’. That way you can edit the settings as you would under Windows.

  7. Thanks for the write up, confused about one simple thing – where do you get the monkersolver DMG file? On their website it only shows the “monkersolver-free-setup.exe” as a downloadable option

    1. You need to purchase MonkerSolver from within the store in MonkerViewer, then you will gain access to the download files for Mac. There is no trial version for Mac.

  8. I used this guide to run Monker on Linux. Every time I restart my server, I can no longer connect through vnc. I get the following errors:

    I tried to resolve the problem by deleting everything from tmp and nuking all dot files in the vnc user home directory. I was unsuccessful and could only fix the problem by reinstalling the OS!

    Anyone else have this problem and know how to prevent it? I’m on the verge of switching back to Windows Server.

  9. monkersolver-setup.dmg is no longer available for download on Now it directs you to a monkerviewer.jar file that once downloaded and extracted doesn’t seem to lead to an application or set up file that I can find. looks like a bunch of java classes. can you help me out here?

    1. Thank you for your comment. The .dmg file required to complete the installation is typically emailed to you upon the purchase of Monkersolver.

  10. The .dmg file seems to be missing MonkerSolver.l4j. How can I change the RAM settings if the settings file is missing?

    1. Hi v1. Please locate the file labelled ‘’ to modify your RAM settings as you would under Windows, using the .l4j file.

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