slow file transfer

BadTenMan

Hi,

I know there are many other topics with similar problems and I tried many of the solutions, but none worked.
My current OVPN setup:
Laptop (Win7), Server (Ubuntu 14.04) in same LAN (Gigabit) with router (with DynDNS entry).
Second PC (Win7), which has to be integrated via OVPN, another location. Because of that I need the DynDNS.

File transfer speeds were tested with putty scp.
Laptop -> Server:
Lan pure: 14.0 MB/s (acceptable value for me.)
Connecting via DynDNS: 3.0 MB/s (still pretty ok.)
OpenVPN via LAN IP: 5.5 MB/s
OpenVPN via DynDNS: 0.2 MB/s (very bad if you want to do backups using that connection)
set tun-MTU to 1272: 0.2 MB/s (thats the highest MTU possible without splitting packets, determined via "ping -f -l", set on both: laptop and server)

Server -> Laptop:
OpenVPN via DynDNS: 3.5 MB/s (that way it is much better!)

I already changed the MTU size in the tap adapter settings, but no change.
Maybe you know a solution to this.

Thanks,
BadTenMan

My configs:
Server:

local 192.168.178.28
port 1194
proto udp
dev tun
tun-mtu 1272
ca ./easy-rsa2/keys/ca.crt
cert ./easy-rsa2/keys/server.crt
key ./easy-rsa2/keys/server.key  # This file should be kept secret
dh ./easy-rsa2/keys/dh2048.pem
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
keepalive 10 120
comp-lzo
user nobody
group nogroup
persist-key
persist-tun
status openvpn-status.log
verb 3

Laptop:

client
dev tun
tun-mtu 1272
proto udp
remote <<my DNS-Address>> <<Port>>
remote-cert-tls server
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
cert Laptop.crt
key Laptop.key
ns-cert-type server
comp-lzo
verb 3

BadTenMan

Update (can't find edit button):
I used Wireshark to analyse the traffic going through my ethernet connection.
OpenVPN connection:
3 times: 3463 11.070866000 10.8.0.6 10.8.0.1 SSHv2 1286 Client: Encrypted packet (len=1232)
1 time: 3461 11.060136000 10.8.0.6 10.8.0.1 SSHv2 534 Client: Encrypted packet (len=480)

Ethernet connection to Router:
in turns:
6500 28.398252000 <my Lan-IP> <Router IP> IPv4 1314 Fragmented IP protocol (proto=UDP 17, off=0, ID=4700) [Reassembled in #6501]
6501 28.398258000 <my Lan-IP> <Router IP> UDP 71 Source port: 49416 Destination port: <DynDNS-Port for OVPN>

Any clue why this gets fragmented?

BadTenMan

server -> Laptop:
only these:
24388 11.233387000 <Router IP> <my Lan-IP> UDP 1351 Source port: <DynDNS-Port for OVPN> Destination port: 49416

Seems that the packages for laptop->server are too small.
1351:71 ~= 19:1
200KB/s : 3500KB/s ~= 17:1

Could this be the problem? Is there a way to increase the minimum packet size?

BadTenMan

Hi again.
I did much testing the last days and found out that it is partly a MTU problem.
Reducing to 1230 works and gives me 2.2 MB/s, even more than I expected.
But it seems that most of the speed is eaten up by my port forwarding.
Pure scp 14 up/18 down -> 3 up/4.2 down with port forwarding in the same LAN. (both no OpenVPN)
So my final two questions before this can be closed:
Are you experiencing the same drop (75-80% less speed) when you use port forwarding in the same LAN?
Maybe someone wants to do a short test to find out. 😉
Is this a router issue?

BadTenMan