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    Subjectmultiple TCP sockets with same (srcip,dstip,sport,dport)
    Date
    Hi,
    Would the TCP gurus look at the following case and comment on it ?
    (this is 2.2.13)

    Its possible to create multiple sockets in the SYN_RECV state
    all of which have the same 4-tuple.

    Here is the scenario :
    If a client machine sends out a SYN and the server sends a SYN-ACK
    back and puts the new socket in SYN_RECV state. If the client machine
    dies before it receives the SYN-ACK... the local port on the client can
    be reused. If I start my client application again, it will reuse that port
    and send another SYN with a different sequence number..

    The problem is in the function tcp_check_req()... If you get a SYN
    that hashes to the listening socket, we do check for retransmission
    but we do not check for the fact that if it is not a retransmission, it
    might still be from the same remote port as the remote port of
    the half-open structure.

    I am not sure what the spec has to say in this case (probably nothing)
    But we could easily toss away the old half-open req (since we
    are sure that the remote end doesnt have any state about it anyway)
    and accept the new SYN..(there is still the problem that the old
    SYN-ACK might be hanging out somewhere and could cause
    this new connection to be RESET)

    I am not sure how other UNIX variants deal with this problem.

    Thanks
    Rajeev



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