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    Subjectpcap misses packets - HELP!!!
     Hello, all!

    I need to sniff a email traffic on a heavily loaded network.
    Currently i try to use dsniff package whose operation is based on
    libpcap. There are problems related to packet loss. Some packets are
    just not captured, this causes severe troubles (for example missing
    FIN packet leads to abandoned connection tracking and memory leak).
    Missing pieces of mails are also not good.
    This problem happens when more than one stream of large data is
    transferred concurrently (for example we send more than one 2 mb
    message via SMTP at the same moment). A friend of mine told that this
    is known problem of pcap which addresses packet copying from kernel
    space to user space.
    Are there any alternative solutions working in PROMISC mode (the
    traffic is running between two machines which we can't modify by
    project conditions and we have a third machine on this network with
    an interface in PROMISC mode)? I've tried iptables ULOG target, but
    this catches only UDP broadcasts despite i set PROMISC for the
    interface using ifconfig.
    May be some cnahging sysctl values helps here? I've looked at the
    kernel source and learned that dropping packets being captured depends
    on socket input buffer size and something other in skbuff subsystem
    (some conditions which are unclear to me).

    --
    Best regards,
    Pavel mailto:sonic_amiga@rambler.ru

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