Description of problem:

If an ICMP error is received in the middle of a connection opening phase,
the port redirection fails and no redirection is performed.

Here is an example of a testing system.

client                        server
10.33.140.104                 10.33.140.110
+-----------------+           +-----------------------------+
|      +--------+ |           | +--------+      +--------+  |
|port: |iptables| | --------> | |iptables|----->| httpd  |  |
| 41292|  (1)   | |           | |  (2)   |      |port:80 |  |
|      |        | |           | |port:   |      |        |  |
|      |        | | <-------- | |  8089  |<-----|        |  |
|      +--------+ |           | +--------+      +--------+  |
+-----------------+           +-----------------------------+

1. Configure the iptables of the client so that the client sends error
   packets of the network to the server.

The iptables marked as (1) in the above figure is configured as follows.
 # iptables -F
 # iptables -A INPUT -p tcp -m tcp --sport 8089 -j REJECT --reject-with icmp-host-unreachable
 # iptables -P INPUT ACCEPT
 # iptables -P OUTPUT ACCEPT
 # service iptables save
 # service iptables restart

2. Configure the iptables of the server.

The iptables marked as (2) in the above figure is configured as follows.
 # iptables -F
 # iptables -t nat -A PREROUTING  -p tcp -m tcp --dport 8089 -j REDIRECT --to-ports 80
 # iptables -P INPUT ACCEPT
 # iptables -P OUTPUT ACCEPT
 # service iptables save
 # service iptables restart


3. Start httpd on server.
 # service httpd start


4. Run the tcpdump on the client to capture packets which both the source
   address and the destination address are the server's IP address.
e.g.)
 # tcpdump -i eth0 -s 256 src 10.33.140.110 or dst 10.33.140.110


5. Access from the client to the port 8089 in the server.
e.g.)
 # telnet <server's-IP-address> 8089
 
6. Confirm that the server directly responds from the port 80 to the client
   after a network error (Destination unreachable) occurs.

   10.33.140.104 10.33.140.110 TCP 41292 > 8089 [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=65644314 TSER=0 WS=7
   10.33.140.110 10.33.140.104 TCP 8089 > 41292 [SYN, ACK] Seq=0 Ack=1 Win=5792 Len=0 MSS=1460 TSV=81687816 TSER=65644314 WS=2
   10.33.140.104 10.33.140.110 ICMP Destination unreachable (Host unreachable)[Packet size limited during capture]
   10.33.140.104 10.33.140.110 TCP 41292 > 8089 [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=65647314 TSER=0 WS=7
   10.33.140.110 10.33.140.104 TCP 80 > 41292 [SYN, ACK] Seq=0 Ack=0 Win=5792 Len=0 MSS=1460 TSV=81690816 TSER=65647314 WS=2
   10.33.140.104 10.33.140.110 TCP 41292 > 80 [RST] Seq=0 Win=0 Len=0
   10.33.140.104 10.33.140.110 TCP 41292 > 8089 [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=65653314 TSER=0 WS=7


Version-Release number of selected component (if applicable):
kernel-2.6.9-67.EL & newer

How reproducible:
Always