The question is that my application does not send ACK packet after receiving SYN,ACK response from server. I've managed to get dump when using different connection, but i could not find any critical differences between request-responses, which would result in such an issue.

Here is short version for "wrong" session, initiated by client:

```
[SYN] Seq=0 Win=65535 Len=0 MSS=1460 SACK_PERM=1 TSval=17625416 TSecr=0 WS=64
[SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1440 SACK_PERM=1 WS=256
[SYN] Seq=0 Win=65535 Len=0 MSS=1460 SACK_PERM=1 TSval=17625720 TSecr=0 WS=64
[SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1440 SACK_PERM=1 WS=256
[SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1440 SACK_PERM=1 WS=256
[SYN] Seq=0 Win=65535 Len=0 MSS=1460 SACK_PERM=1 TSval=17626322 TSecr=0 WS=64
[SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1440 SACK_PERM=1 WS=256
[SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1440 SACK_PERM=1 WS=256
[SYN] Seq=0 Win=65535 Len=0 MSS=1460 SACK_PERM=1 TSval=17627524 TSecr=0 WS=64
[SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1440 SACK_PERM=1 WS=256
[SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1440 SACK_PERM=1 WS=256
```

here is short version for correct session:

```
[SYN] Seq=0 Win=65535 Len=0 MSS=1460 SACK_PERM=1 TSval=76086 TSecr=0 WS=64
[SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1380 SACK_PERM=1 WS=256
[ACK] Seq=1 Ack=1 Win=65536 Len=0
[PSH, ACK] Seq=1 Ack=1 Win=65536 Len=259[Packet size limited during capture]
[ACK] Seq=1 Ack=260 Win=16128 Len=0
```

I'm totaly stuck here - i can find any evidence for what could happen with client-side.