Re: Extremely poor OpenVPN performance, help wanted

[Tom Rymes <trymes@rymes.com>]

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Peter,

Is the issue reproducible on different OS and different OpenVPN clients? There’s a chance that the issue lies with FreeBSD or how you are configuring the VMs at different locations.

Tom

> On Sep 24, 2019, at 9:23 AM, <peter.mueller(a)ipfire.org> <peter.mueller(a)ipfire.org> wrote:
> 
> Hello list,
> 
> as mentioned several times before, I am experiencing OpenVPN performance
> problems. Since I am out of ideas by now, asking here to help seemed to
> make sense to me, as I am not sure whether it can be traced to a bug or not.
> 
> Test setup is as follows:
> (a) IPFire is freshly installed on a testing machine with Core Update 135 (x86_64).
>    The machine is connected to the internet via DSL (link has 100 Mbit/sec
>    down capacity with MTU set to 1492) and runs dial-in by itself. No
>    cascading router or NAT in place here.
> (b) The remote part is a VM hosted at a big German hosting company, with
>    FreeBSD 12 installed (OpenVPN 2.4.7). Uplink is 1 Gbit/sec with MTU =
>    1492.
> (c) Both systems are able to submit ICMP packets up to 1492 bits, so MTU
>    is set correctly on both interfaces.
> (d) The VM is establishing an OpenVPN roadwarrior connection to the IPFire
>    machine, which can be set up successfully and uses AES-256-GCM (SHA 512)
>    for data channel. Tunnel MTU is set to 1400 bytes.
> 
> Downloading a test file via SCP from the VM using the OpenVPN connection
> takes ages and results in throughput between 400 and 700 kB/sec. While
> normal ICMP latency through the tunnel is around 35 ms, it fluctuates between
> 40 and 500 ms while download is running.
> 
> Needless to say, a bandwidth of 700 kB/sec is unacceptable. Disabling
> Suricata speeds up to ~ 1.2 MB/sec, disabling Quality of Service (QoS)
> does not have any big effects.
> 
> Since there are some clients using OpenVPN in restricted environments,
> TCP and port 443 is more or less fixed. Switching to UDP causes a small
> improvement (~ 800 kB/sec), but does not seem to cure the root cause.
> 
> This effect is reproducible with multiple VMs at multiple locations,
> so I do not think it is related to network outages at one certain hoster.
> 
> What am I doing wrong? Is anyone experiencing the same problem?
> 
> As mentioned in the Subject line, any help is appreciated.
> 
> Thanks, and best regards,
> Peter Müller