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I've an openVPN client which runs on windows2008 R2 server and through this windows 2008, I'm trying to do static nat to a machine which lies behind this win2008s real network. Here is my configuration for 2008 server;

  • OpenVPN server;
  • OpenVPN connection: "Local Area Connection 2"
  • Local network: "Local Area Connection"

output of my NAT configuration on 2008 server

    # ----------------------------------
    # NAT configuration
    # ----------------------------------
    pushd routing ip nat
    set global tcptimeoutmins=1440 udptimeoutmins=1 loglevel=ERROR
    #NAT Configuration For Interface Local Area Connection 2
    add interface name="Local Area Connection 2" mode=FULL
    add addressrange name="Local Area Connection 2" start= end= mask=
    add addressmapping name="Local Area Connection 2" public= private= inboundsessions=enable
    #NAT Configuration For Interface Local Area Connection
    add interface name="Local Area Connection" mode=PRIVATE

When I try to ping from openvpn server or connect to a tcp port on it, I see destination nat is done on windows 2008 server and my packets are sent to but with source ip

  19:54:25.046131 IP > Flags [S], seq 870055875, win 5840, options [mss 1350,sackOK,TS val 8948005 ecr 0,nop,wscale 7], length 0
19:54:25.046198 IP > Flags [R.], seq 0, ack 870055876, win 0, length 0
  19:54:28.044561 IP > Flags [S], seq 870055875, win 5840, options [mss 1350,sackOK,TS val 8951005 ecr 0,nop,wscale 7], length 0

and for sure, returning packets does not find their way to originator then.I also tried not to map hosts directly but service/port translation but this didn't work either. In my linux boxes, I can of course change the source IP address while doing nat with iptables but for very same scenario, I couldn't find how to do this on windows.

So, do you have any idea how to change source ip while doing NAT with windows servers?

thanks for the help in advance


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