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I have a desktop running Ubuntu 14. This server is connected to a 3rd party VPN service, subnet 10.186.1.0/24. I have an Asus router, and have enabled the VPN service on that router so that I can connect to my home network when out. That network is configured as 10.8.1.0/24. I have updated the firewall on the Ubuntu box to allow traffic in and out from the second VPN network on any interface.

When the VPN on the Ubuntu box is up (10.182.1.0/24), and I connect from a client on the second VPN, I am unable to connect to the Ubuntu box. Connections timeout, nothing in the ufw or syslog.

If I drop the VPN connection on the Ubuntu box, I am able to connect from the remote client without problem.

Any suggestions on where I could look for logging? I already enabled full logging for iptables and ufw, nothing shows when I attempt to make the connection. Perhaps the 10.182.1.0/24 VPN is preventing the routing of connections from the 10.8.1.0/24 client?

Any suggestions on places to look would be greatly appreciated.

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  • Another interesting piece - from the local network, I can make the same connection to the Ubuntu server from the local network, regardless of whether it has its VPN connection up or not.
    – bcrooker
    Feb 16, 2016 at 3:00

2 Answers 2

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In cases like this, it is very difficult to diagnose the problem with the amount of info you have provided: normally, you should provide the routing tables of both router and Ubuntu pc.

However, in this extremely lucky case, I think the problem is that the Ubuntu box, once connected to its VPN, will try to reply to connection attempts from the second VPN by routing them thru the first VPN. Thus all you need to do is to add a route that forces a correct routing. On the Ubuntu machine, try:

ip route add 10.8.1.0/24 via Ip.Addres.Of.Asus.Router dev eth0

having assumed your Ubuntu pc is connected via cable, not via wifi; otherwise, modify accordingly.

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That is a known and unsolved issue of linux since a long time.

You can try using GopenVPN which is a frontend GUI for openvpn

You can connect to multiple VPN connections from the terminal just go to the directory where your .ovpn files are located along with their certificates and launch :

sudo openvpn --config connection_1.ovpn &
sudo openvpn --config connection_2.ovpn &
...
sudo openvpn --config connection_N.ovpn &

only replace connection_N.ovpn with the config file you are using.

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