AVG is blocking application GNS3

We appreciate you taking time to notify us. Thank you.

I am having a similar issue getting GNS3 to work.  I previously had 0.8.3 working but every time I tried to open an existing topology - I got errors.

So I installed 0.8.7 and when I try to import an existing topology I get the following error:

=== GNS3 0.8.7 traceback on 06 Dec 2015 10:34:13 ===Traceback (most recent call last):

  File "GNS3\NETFile.pyo", line 648, in import_net_file

  File "GNS3\Dynagen\dynagen.pyo", line 1533, in import_config

  File "GNS3\Dynagen\dynamips_lib.pyo", line 3419, in init

  File "GNS3\Dynagen\dynamips_lib.pyo", line 2163, in init

  File "GNS3\Dynagen\dynamips_lib.pyo", line 4975, in send

So I figured, lets try to create a new topology and rebuild from scratch.

When I run "test settings" on Dynamips  I get an error -  Fatal error on NTCreateEvent.  After this DOS window auto-closes in 5 seconds, GNS3 comes back and says Dynamips 0.2.12-x86/Windows stable) successfully started.  I have uninstalled and reinstall GNS3 3x now - once even with Admin rights.  Still for some reason something is making it not work.

So I disabled AVG for 15 minutes and everything worked fine.  Spent 8 hours today testing and removing numerous pieces of suspected s/w on my W7 system but it was AVG that has been found to be the culprit.

Hello Doug,
We regret for the inconvenience caused. Please try to add the applications to the exception list so that AVG program will not block the program on any occasion. Please have a look at this article http://avgread.me/18WB2dg to add a program to the exception list. Please feel free to contact us for further assistance.
Thank you.

>> This is the best solution:  I tried to set the exceptions for gns3server.exe and dynamips.exe and it didn't work for me. So, I sent ahead and set the whole folder for the exception.  I my case it was c:\program files\GNS3 . This worked for me.
Options ▬► Advanced Settings ▬► Exceptions ▬► Add Exception ▬► Finally we add all the GNS3 folder and we click ok and ok. We are done. GNS3 version 0.8.7

Hello Doug & Hank.

We apologize for the inconvenience caused. We would require more information to analyze the issue and assist you with it.
Please follow these steps to send us diagnostic information from your computer. This information will allow us to analyze the situation and provide you with a solution:

Click on this link http://www.avg.com/filedir/util/AVG_SysInfo.exe to download the AVG SysInfo tool.
Run the downloaded tool.
Click Continue to agree with AVG’s license agreement and privacy policy. AVG SysInfo will now gather the data.
Once the diagnostic output is ready, you may add comments, or click Attach file or Screenshot to provide us with extra information.
Fill in your email address, and then click Send output.
We will analyze the received files and provide you with further information.
Thank you.

With latest version of AVG setting individual exceptions for GNS3 did not work but also setting exception for the entire GNS folder as mentioned above by Ken Stephens works perfectly. Hope this may prove useful for others struggling to get this simulator working for CCNA training.

I use the application GNS3 to practice for Cisco certifications.   ( www.gns3.com )

It has always worked great for me until this last upgrade of the AVG softwoare.

Now the only way I can get my GNS3 to work is to uninstall my AVG.

How can I fix my AVG software so it will let me run my GNS3 software?

Mindy Bowen answer worked for me today. Thank you.

I tried to set the exceptions for gns3server.exe and dynamips.exe and it didn't work for me. So, I sent ahead and set the whole folder for the exception.  I my case it was c:\program files\GNS3 . This worked for me.

I had this problem and I managed to get it resolved.

You need to add a particular part of GNS3 to the AVG exception list. It will be the executable dynamips.exe. For me it was located here:

C:\Program Files\GNS3\dynamips\dynamips.exe

Hope this helps someone else!

AVG does not give me any blocking popup.

I just get the error  that I mentioned above, from the GNS3 application.

Server error from 127.0.0.1:8000: R2: Lost communication with 127.0.0.1:61883 :[WinError 64] The specified network name is no longer available, Dynamips process running: True

http://www.gns3.com/

So for me running GNS3 with GNS3 VM in VMWARE I had the following problems and the solutions below.

note GNS3 VM was created with Vmnet0 Bridged

  • First issue was starting GNS3 it would not connect to the GNS3 VM
    • Advanced settings-> expert mode->advanced settings
    • check box "allow any traffic from/to virtual machines supported by firewall"
  • Second issue, I got my lab built in GNS3 and the VMWare/VM inside of GNS3 could not surf the web unless I turned off the firewall on the host. After a lot of testing I found out that AVG firewall is blocking outbound traffic from the VM... don't know why but it was.
    • Defined Networks
      • I added all ip subnets and ips of VM subnets.
    • System Services
      • protocol TCP
      • direction OUT
      • local ports ALL
      • remote ports ALL
      • remote address SAFE NETWORK
After all of these changes GNS3 starts with no issues and I am able to surf the web from within my VMware windows 7 VM without turning the AVG firewall off on my host machine.

hop this helps someone.

I am having a similar issue getting GNS3 to work.  I previously had 0.8.3 working but every time I tried to open an existing topology - I got errors.

So I installed 0.8.7 and when I try to import an existing topology I get the following error:

=== GNS3 0.8.7 traceback on 06 Dec 2015 10:34:13 ===Traceback (most recent call last):

  File "GNS3\NETFile.pyo", line 648, in import_net_file

  File "GNS3\Dynagen\dynagen.pyo", line 1533, in import_config

  File "GNS3\Dynagen\dynamips_lib.pyo", line 3419, in init

  File "GNS3\Dynagen\dynamips_lib.pyo", line 2163, in init

  File "GNS3\Dynagen\dynamips_lib.pyo", line 4975, in send

So I figured, lets try to create a new topology and rebuild from scratch.

When I run "test settings" on Dynamips  I get an error -  Fatal error on NTCreateEvent.  After this DOS window auto-closes in 5 seconds, GNS3 comes back and says Dynamips 0.2.12-x86/Windows stable) successfully started.  I have uninstalled and reinstall GNS3 3x now - once even with Admin rights.  Still for some reason something is making it not work.

So I disabled AVG for 15 minutes and everything worked fine.  Spent 8 hours today testing and removing numerous pieces of suspected s/w on my W7 system but it was AVG that has been found to be the culprit.

We appreciate you taking time to notify us. Thank you.

Mindy Bowen answer worked for me today. Thank you.

I do not receive any error message when I add the application to the exception list.

It seems to add the application to the exception list without any problem.

However, the application is still being blocked.

Thank you for your assistance.

I had this problem and I managed to get it resolved.

You need to add a particular part of GNS3 to the AVG exception list. It will be the executable dynamips.exe. For me it was located here:

C:\Program Files\GNS3\dynamips\dynamips.exe

Hope this helps someone else!

I tried to set the exceptions for gns3server.exe and dynamips.exe and it didn't work for me. So, I sent ahead and set the whole folder for the exception.  I my case it was c:\program files\GNS3 . This worked for me.

Cesar,
Thank you for sharing the workaround. Glad to know that this worked for you.
We appreciate your efforts. Please feel free to contact us should you need any assistance. Thank you.

Hello Doug & Hank.

We apologize for the inconvenience caused. We would require more information to analyze the issue and assist you with it.
Please follow these steps to send us diagnostic information from your computer. This information will allow us to analyze the situation and provide you with a solution:

Click on this link http://www.avg.com/filedir/util/AVG_SysInfo.exe to download the AVG SysInfo tool.
Run the downloaded tool.
Click Continue to agree with AVG’s license agreement and privacy policy. AVG SysInfo will now gather the data.
Once the diagnostic output is ready, you may add comments, or click Attach file or Screenshot to provide us with extra information.
Fill in your email address, and then click Send output.
We will analyze the received files and provide you with further information.
Thank you.