address translation

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This topic contains 4 replies, has 4 voices, and was last updated by  Vadim Smirnov 13 years ago.

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  • #4842

    hex
    Participant

    Hi,

    I am trying to use your pkacet filter for writing a nat. But i am not sure sure how to do it.

    I have laready downloaded and read the rfc on nat.

    However, are there any special thinks to consider when using your pkt filter ??

    #5544

    Vadim Smirnov
    Moderator

    However, are there any special thinks to consider when using your pkt filter ??

    I’m not sure what you actually mean here, but there is no technical problems to realize NAT using WinpkFilter.

    #5545

    bk
    Participant

    To NAT you must change the source or destination IP in a direction and do the opposite in the other direction. Remember to recalculate the checksum of the packets. You’ll have no problems using winpkfilter driver to NAT, I’ve done it without problems.

    #5546

    wed3460
    Participant

    HI BK:
    my architecture like following

    Client(WLAN)< --->< --->Server(WLAN)-NAT-Server(WAN)< --->Internet

    i can receive the packet from Client and modify packet ,recauclate checksum(it’s ok),but i cant forward to other NIC(WAN)

    so i got trouble to implement NAT
    the problem:
    how to bind the different nic and translate packet to other NIC
    and i confuse the how to used the “SendPacketToAdapter” and
    “SendPacketToMstcp”
    or have else procedure i havt to notice. please help me , thanks

    #5547

    Vadim Smirnov
    Moderator

    One of the approaches (the easiest from my point of view) is filtering Server(WAN) interface substituting the original IP (if it is from LAN) in the outgoing packet with Server WAN card IP (port substitution also should be done in order to perform backward mapping). For incoming packets on the Server (WAN) interface you should match against NAT table and perform the reversed operation. Please note that packet forwarding should be enabled on the Server. You don’t need to route packets youself, TCP/IP will do it for you.

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