openvpn on linux allows you to connect to 2 VPNs at the same time, how does that work?

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The interface allows me to be connected to more than 1 VPN at once but what does really happen behind the scenes?

IP finder sites show the IP of the first VPN i got connected to.

But as soon as I disconnect from the first it shows the IP of the second.

I guess that is nice if you want to switch VPNs without being exposed for a second, but other than that what really happens behind the scenes when you do that?

NaDre

The interface allows me to be connected to more than 1 VPN at once but what does really happen behind the scenes?
IP finder sites show the IP of the first VPN i got connected to.
But as soon as I disconnect from the first it shows the IP of the second.

I guess that is nice if you want to switch VPNs without being exposed for a second, but other than that what really happens behind the scenes when you do that?

If you don't intervene to take control of the routing table, both VPN connections will attempt to become the "default gateway" by adding two entries with a netmask of "128.0.0.0".

See see the description of the "def1" flag for the "--redirect-gateway" option in the OpenVPN man page:

https://community.openvpn.net/openvpn/wiki/Openvpn24ManPage

"Use this flag to override the default gateway by using 0.0.0.0/1 and 128.0.0.0/1 rather than 0.0.0.0/0. This has the benefit of overriding but not wiping out the original default gateway."

With competing default gateways you will get unpredictable results. To use two VPN connections you will need to learn how to use the routing table, and you may (depending on what you want to achieve) need to learn about "source address routing".

Without knowing what you want to use a second VPN connection for I can't really say much more. But these posts discuss this for having torrent traffic separate from all the rest:

https://airvpn.org/topic/9491-guide-to-setting-up-vpn-just-for-torrenting-on-windows/page-4?do=findComment&comment=66214

https://airvpn.org/topic/27598-traffic-split-on-debian-7/?do=findComment&comment=73698

Following the links may lead you to information that is relevant to your goals.