config DNS failed

[apstav]

Hello,
I'm new here, i have installed forticlient 7.4 in ubuntu 24.04.
I was connected to my VPN server. after a week when i tried to reconect i had this error "config DNS failed".

these are the logs from the forticlient:
20241212 13:01:50.744 TZ=+0200 [sslvpn:INFO] main:2168 Init
20241212 13:01:50.744 TZ=+0200 [sslvpn:INFO] main:2186 VPN is running in restore DNS mode
20241212 13:01:50.750 TZ=+0200 [sslvpn:INFO] nettools:1854 More than one device with index 2 can be found
20241212 13:01:50.751 TZ=+0200 [sslvpn:INFO] nettools:1854 Device address details: local_address xx.xx.xx.xx, device_index 2, device name eth0 (read from netlink)
20241212 13:01:50.751 TZ=+0200 [sslvpn:INFO] nettools:1854 Device address details: local_address xxxx::xxx:xxxx:xxxx:xxxx, device_index 2, device name eth0 (read from netlink)
20241212 13:01:50.781 TZ=+0200 [sslvpn:DEBG] vpn_util:299 Get connection name: netplan-eth0
20241212 13:01:50.791 TZ=+0200 [sslvpn:INFO] nmtools:865 Network Manager settings backup file doesn't exist
20241212 13:01:50.791 TZ=+0200 [sslvpn:DEBG] nmtools:1200 No connections to restore
20241212 13:01:50.791 TZ=+0200 [sslvpn:DEBG] dns:302 File /etc/nm_resolv.forticlient.backup doesn't exist
20241212 13:01:50.826 TZ=+0200 [sslvpn:DEBG] vpn_util:299 List fctvpn connection: netplan-eth0
lo
br-0174ab01e3e8
docker0
br-0174ab01e3e8
docker0
20241212 13:01:50.826 TZ=+0200 [sslvpn:DEBG] dns:982 default interface restore: 1, vpn interface restore: 1
20241212 13:01:50.827 TZ=+0200 [sslvpn:DEBG] mtu:121 Restore MTU.
20241212 13:01:50.827 TZ=+0200 [sslvpn:DEBG] mtu:125 No MTU backup file was found. Skip.

 Any ideas how to solve this?
Thank you

[Anthony_E]

Hello apstav,

Thank you for using the Community Forum. I will seek to get you an answer or help. We will reply to this thread with an update as soon as possible.

Thanks,

[apstav · Accepted solution]

Hello Antony,

I identified the issue as a problem with the eth0 network interface when it is managed by NetworkManager. It appears the error was caused by two interfaces being configured with the same settings—likely a misconfiguration on my part.

Thank you for your time and assistance.

Best regards,
Apostolis

[Anthony_E]

Thanks a lot for sharing your solution :) and never hesitate to open a discussion in the forum when needed :)

[jciconet]

Hey!

We got the same error, it appears to be related to this bug > https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/2089930

How did u fix it?

[tonichaz]

Problem: VPN Conflicts with Docker Networking

I was experiencing the same issue where my VPN wouldn't connect properly when Docker was running. The problem was related to conflicts between the Docker-managed network interfaces and NetworkManager. Specifically, NetworkManager was trying to manage Docker’s interfaces (docker0 and br-*), leading to duplicate configurations and routing conflicts.

I’m not sure if the rest of you are experiencing the same issue, but I hope my solution can help someone.

Solution: Exclude Docker Interfaces from NetworkManager

To resolve the issue, I excluded Docker’s network interfaces from being managed by NetworkManager. This prevents NetworkManager from interfering with Docker's networking and allows the VPN to work correctly.

Here’s how to do it:

1. Edit the NetworkManager Configuration
   Add a rule to ignore Docker interfaces. Open the configuration file:

   sudo nano /etc/NetworkManager/NetworkManager.conf

2. Add the Following Lines
   Insert the following under the [keyfile] section:

   [keyfile]
   unmanaged-devices=interface-name:docker0;interface-name:br-*
   • docker0: The default Docker bridge network interface.
   • br-*: Custom bridge networks created by Docker.

3. Restart NetworkManager
   Apply the changes by restarting NetworkManager:

   sudo systemctl restart NetworkManager

4. Restart Docker
   After restarting NetworkManager, restart Docker to ensure the interfaces are configured correctly:

   sudo systemctl restart docker

[jciconet]

Man u're a beast!!! Thank u very much, literally saved my end of year :)

[sai-sysadmin]

As a side comment this also fixes the Config routing table failed issue in our Ubuntu systems. Not sure if Fortinet can take a look at this to try and come up with a fix, it would be greatly appreciated! Our Windows and macOS users have never had an issue with the Forticlient.