Cisco AnyConnect - [SOLVED] Untrusted VPN Server Blocked in Ubuntu

If you are a cisco anyconnect vpn user you must faced "Untrusted Server Blocked" issue in your windows or linux server. I faced this issue recently in Ubuntu 16.04 server when connecting cisco anyconnect utilizing digital certificate. I did some steps in my way that really helped me to fix this issue. I expect these steps may fix this issue in the windows server also. So friends, in this post i am going to explain you how i fixed "Untrusted Server Blocked" issue for cisco anyconnect. So stay tuned with the post to fix this issue.

What is Untrusted Server Blocked

Untrusted Server Blocked occurs only when a cisco anyconnect vpn user try to establish connection between local server to the remote server with utilizing digital certificate if the digital certificate is found missing from the browser. Cisco anyconnect restrict the user to connect local server to the remote server and display this error message in a popup window.

How to Fix Untrusted Server Blocked Issue 

I faced this issue when i was trying to connect with cisco anyconnect utilizing my vpn digital certificate in ubuntu 16.04 server. Once i got this error message, at first i checked whether the digital certificate is available or removed from the browser. I found my digital certificate was removed automatically. After that i tried to import the digital certificate again but failed to import due to unknown reason. I tried several times and every time i got the same result.

After that i switch to the cisco anyconnect settings and uncheck the Block connection to untrusted servers option and try to reconnect. But i got the same result also.

I then decide to import the digital certificate on another machine to check whether the certificate was ok or may got corrupt. But on the other machine certificate was successfully imported. Now i was confirmed that something happens either to the browser or the cisco anyconnect or the operating system. Now i was damn sure that problem was with either browser or cisco anyconnect since i found the server and the digital certificate was working fine.

Now this time i decided to update the browser. I updated the browser as i thought and again try to import the digital certificate and you won't believe this time the certificate was successfully imported. It gives me a little smile on my face. But that smile did not last long. When i tried to connect, all the little smile went just like all the air come out from a balloon at once.

This time i decide to uninstall the cisco anyconnect. After that i download the version of cisco anyconnect and reinstall it into the server. When i again try to connect cisco anyconnect, this time cisco anyconnect able to determine the digital certificate and username appears prefilled as it was appear before getting the Untrusted Server Blocked error message. This time i was able to connect to the remote server and it gave me a big smile on my face. I expect this method may work in windows server also.

Steps to Update Firefox

You can update firefox manually or use terminal to update using the following the below commands.

Step 1. Open terminal [ Ctrl + Alt +T ]
Step 2. #sudo add-apt-repository ppa:ubuntu-mozilla-security/ppa
Step 3. #sudo apt update && sudo apt install firefox
That's it!

If you have installed firefox, then it will replace the older version of firefox.

Steps to Import Digital Certificate

To import the digital certificate, follow the below steps

Step 1. Open Firefox browser
Step 2. Click Edit and then Preferences or click menu button and then click Preferences
Step 3. Click Advanced icon
Step 4. Click Certificates and then click View Certificates
Step 5. Click Your Certificates and then click Import button
Step 6. Browse the digital certificate file and click Open button
Step 7. Now enter the Private Key of the digital certificate file and click O.K
Step 8. You will get message “successfully restored your security certificate(s) and private key(s)”
That's it.

Steps to Uninstall Cisco AnyConnect

You can uninstall the cisco anyconnect from ubuntu server with the below commands. Simple open the terminal by pressing Ctrl + Alt +T on the keyboard and type the following below commands.

sudo /opt/cisco/vpn/bin/

Steps to Install Cisco AnyConnect

Before the installation, you must need to download the latest version of the cisco anyconnect. Follow the below steps to download and install Cisco anyconnect in your ubuntu 16.04 server.

Step 1. Go to and then hover mouse pointer on Software and then click VPN Client for linux 64-bit 4.5
Step 2. Change download location to Desktop and Click Save button to download the file.
Step 3. Now extract the downloaded file i.e, anyconnect-linux64-4.5.04029-k9.tar.gz
Step 4. Now open terminal on Desktop
Step 5. Type command #cd Desktop/
Step 6. Type command #cd anyconnect-linux64-4.5.04029
Step 7. Type command #cd vpn
Step 8. Type command #sudo apt-get update
Step 9. Type command #sudo apt-get install libpangox-1.0-0 libcanberra-gtk-module
Step 10. Type command #./
Step 11. Press Y when asked.
Step 12. Open Cisco Anyconnect secure mobility client
Step 13. Type against Connect to and then click Connect
Step 14. After that enter vpn password and then click Connect and then click Accept.
That's it!

So friends, if you like this post then feel free to comment and share this post on so that others can get the benefit of this post.
Cisco AnyConnect - [SOLVED] Untrusted VPN Server Blocked in Ubuntu Cisco AnyConnect - [SOLVED] Untrusted VPN Server Blocked in Ubuntu Reviewed by Mani on June 30, 2019 Rating: 5

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