Slower than expected speeds - VPN at router level, DD-WRT

[Lordvpn 4]

Running AirVPN over DD-WRT on a WNDR3700v4 and experiencing lower than expected out of tunnel and in tunnel speeds.

 

No VPN

Ookla Speed Test puts me at 40.00mbps downstream

 

AirVPN

Out of Tunnel to the closest server(ge), results in 18mbps downstream

In tunnel results in 9mbps

 

 

I tried some other servers potentially with better routes, and got similar speeds. I am perplexed why my out of tunnel is so low, and also concerned my in tunnel is 50% less.

Next thing was to use different ports (and made sure to use accompanying DNS as well). This changed nothing in the way of speed.

 

 

 

 

I pondered whether it was the router hardware not keeping up with the encryption however I have used other VPN services via OpenVPN at the router level and saw over 30mbps in those cases.
 

[go558a83nk 362]

just test other ways.  there's no reason why Air would be slower than other VPN.

[Staff 9950]

just test other ways.  there's no reason why Air would be slower than other VPN.

 

Perhaps a possible explanation is a VPN using a Data Channel cipher such as 128 bit BF-CBC, while Air uses AES-256-CBC. Since BF-CBC 128 requires less computational power than AES-256 (except during re-keying, that's slower with Blowfish) the resulting performance difference with consumers' routers CPUs can be significant. We have not implemented BF for some security concerns (a class of keys is particularly weak, 64 bit blocks are used - which can be a potential problem for users exchanging in a VPN big amounts of data - >32 GB in one session, not unusual with several customers of our) and Schneier himself (Blowfish creator) eight years ago recommended to not use Blowfish anymore.

 

See also http://crypto.stackexchange.com/questions/1098/is-blowfish-strong-enough-for-vpn-encryption (in particular, answer by "poncho").

 

Kind regards

[Lordvpn 4]

Thanks both.

 

I have since built the pfSense box and am running at acceptable speeds.