modification of tcp flags using netfilter hooks??

Discussion in 'Linux Networking' started by Sunny, Feb 8, 2006.

  1. Sunny

    Sunny Guest

    Hello,
    I have wriiten a module using netfilter hooks for catching
    packets n then modifying it.. First using NF_IP_PRE_ROUTING hook i am
    trying to modify the incoming tcp packet.. I want to change the tcp
    flags for the incoming packet..I have handled the checksum issues for
    that.. What othere issues i need to handle???
    Thanks...

    Regards
    Sunny
     
    Sunny, Feb 8, 2006
    #1
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  2. Sunny

    Eric Lalitte Guest

    It depends on which flags you're working.
    If it's on URG, you've got to see the urgent pointer in the header.

    If you touch SYN, FIN, ACK or RST, you should'nt count on a normal
    TCP/IP
    connection.
     
    Eric Lalitte, Feb 9, 2006
    #2
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  3. Sunny

    zanettea Guest

    Hi Sunny,
    I am trying to do the same thing. Did you eventually found a solution?

    Thanks,
    Arrigo
     
    zanettea, Oct 20, 2012
    #3
  4. Sunny

    Jorgen Grahn Guest

    You're replying to a posting which is almost seven years old. "Sunny"
    is probably no longer reading this group.

    What are you trying to accomplish? Modifying TCP flags (the
    SYN/ACK/RST/PSH/etc bits) before they reach ip_rcv() seems rather
    pointless, so I'm thinking the solution to your problem probably lies
    elsewhere?

    /Jorgen
     
    Jorgen Grahn, Oct 20, 2012
    #4
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