Firewall Tunnel

I'm running ft_be on windows and ft_fe on linux. I've got OpenSSH running on the windows box, using cygwin, and it works fine, I can connect to it properly and everything. Running it over Firewall Tunnel things stop working. The tunnel sets up fine, sits there waiting for a connection from the client. When the client connects, it disconnects pretty much straight away.

Front end (linux) command and log:

./ft_fe -p 58634 -t 54936 -k 5
proxy_port = 58634 , tunnel_port = 54936, keep_alive_interval = 0 (sec)
udp_mode = 0, socks_mode=0
allowed client ip = any
Frontend(proxy) is waiting for TCP connection request from backend...
Connection established between:
frontend:192.168.0.22.54936 and backend:60.226.61.68.1206
Creating a listening socket for internet TCP client...OK
@@@@@@@ ft_be_fd=4, ft_client_listen_fd=3
The Output Thread is started ... OK
ft_wrt_thread:applying ft_wrt_queue_mutex
ft_wrt_thread:cond_wait queue_empty
Listening to incoming connections ...
Some traffic comes...
New connection initiated by client ...
connection #2, fd = 7, event= POLLIN, max_index=2
new connection established:
client=192.168.0.33.1208
frontend=192.168.0.22.58634
backend=60.226.61.68.1206
Encapsulate a packet of len:0
from client:192.168.0.33.1208
to backend:60.226.61.68.1206
packet type = FT_CLNT_CONN_REQ src ip = 192.168.0.33 src port = 1208 dst ip = 60.226.61.68 dst port = 1206
Data Len = 0
ft_writen: applying ft_wrt_queue_mutex
ft_writen: cond_wait on queue_full
ft_writeln: cond_signal queue_empty
ft_writeln: release ft_wrt_queue_mutex
ft_wrt_thread:releasing ft_wrt_queue_mutex
writing a message from:192.168.0.22.54936 to :60.226.61.68.1206
ft_wrt_thread: sent out a packet of len:24 succesfully
from: 192.168.0.22.54936 to: 60.226.61.68.1206
ft_wrt_thread:applying ft_wrt_queue_mutex
ft_wrt_thread:cond_wait queue_empty
Some traffic comes...
Packet from BE comes ...
!!! TCP tunnel is closed by back end!!!

ft_be -f rurik.gotdns.org -p 54936 -w 58634 -s -k 5

fe_host=rurik.gotdns.org, fe_port=54936, device=eth0, web_port=58634
udp_mode=0, direct_socket=1, socks_mode=0
keep_alive_interval=0(sec)
connection established: from 192.168.0.33:1188==>rurik.gotdns.org:54936
FT_SERV_HOST = 192.168.0.33
local ip is updated to : 192.168.0.33
udp_mode = 0, direct_socket_mode=1
The Output Thread is started ... OK
ft_get_first_sock: No entry exists!
ft_wrt_thread:applying ft_wrt_queue_mutex
ft_wrt_thread:cond_wait queue_empty
@@@ ft_wrt_thread: cond_wait because of wrt_queue_empty
#### ft_message_loop: traffic from tunnel comes...--------------ft_dump_msg_binary----len=24-----------------
FIRE.......!<.=D........
-------------------------------------------------------------
----decap = 24, pkt_len = 24
=============Got a complete ft_packet ====d=======
type = FT_CLNT_CONN_REQ src ip = 192.168.0.33 src port = 1191 dst ip = 60.226.61.68 dst port = 1188 data_len=0
ft_hash_get:before getting hash_mutex
ft_hash_get:releasing hash_mutex
Message type = FT_CLNT_CONN_REQ
Got conn request message from FE
A CLNT_CONN_REQ packet of new flow 192.168.0.33:1191 => 192.168.0.33:58634 is coming!
Sock mutex got by ft_decap
ft_hash_get:before getting hash_mutex
ft_hash_get:releasing hash_mutex

The OpenSSH server is running on port 58634 on the windows machine. I was actually trying to connect the client from the windows machine, which sits behind my router. rurik.gotdns.org is the address of my router, which has port 54936 forwarded to the linux box. But none of that should affect it.

Any help?