On 02.04.2014 18:42, Eric Dumazet wrote: > You could post a tcpdump maybe ? This is a dump from on the tun interface (traffic inside the tunnel). It's an scp upload of a 2MB file. I aborted after a while when not much progress was seen anymore, but you get the idea. What I see: - Frame 28: long delay because I had to enter the key password - Frame 31: the packets seems to be out of order. It has a sequence number that is far ahead of previously sent sequence no's. Some duplicates and retransmissions follow. That pattern repeats randomly all over the trace. - from Frame 73 on: ping pong of ACKs and data, while the data is delayed by ~200ms caused by the select(). The ping pong also shows that there are virtually no packets in flight (see also Window size).