SoftEther VPN User Forum

The vpnserver is installed on a Ubuntu 13.04(32bit) VPS. A Windows client is connected to the vpnserver via L2TP/IPSec with SecureNAT enabled at the vpnserver to connect to the internet. With just one VPN session, vpnserver shoots up to 100% CPU and then the VPN session times out. Why is vpnserver using so much CPU at kernel space?

Attached is output of 'top'.

Edit: Apparently this is due to SecureNAT, nothing can be done about it.

You have to create local bridge with real netcard and use NAT on hardware router.

I have the same problem and over and over again I find the same answer. What really puzzles me is why did the creators bother with providing this optional set up.

In particular it bothers me that every installation guide suggests this option since it is easier (like in my case configuring a bridge isn't trivial due to the configuration of the existing network were my server live) then I find that enabling secureNat completely killed the cpu.

Some forum emphasise that this happens only if bridge and securedNat are simultaneously enable yet that's not true - securedNat alone killed the cpu with only one connection like this post says.

The conclusion I arrived is to stay away from this software. You will be better off investing time installing and configuring other proven solutions like openvpn.

myopenid wrote:
> The vpnserver is installed on a Ubuntu 13.04(32bit) VPS. A Windows client
> is connected to the vpnserver via L2TP/IPSec with SecureNAT enabled at the
> vpnserver to connect to the internet. With just one VPN session, vpnserver
> shoots up to 100% CPU and then the VPN session times out. Why is vpnserver
> using so much CPU at kernel space?
>
> Attached is output of 'top'.
>
> Edit: Apparently this is due to SecureNAT, nothing can be done about it.

try this solution http://www.vpnusers.com/viewtopic.php?f ... 16&p=10815

solved my CPU problem .