NAME
    FlowScan - a system to analyze and report on cflowd flow files

DESCRIPTION
    This document is the FlowScan User Manual $Revision: 1.23 $,
    $Date: 2001/02/28 21:48:08 $. It describes the installation and
    setup of `FlowScan-1.006'.

    FlowScan is a system which scans cflowd-format raw flow files
    and reports on what it finds. There are two report modules that
    are included. The `CampusIO' report module produced the graphs
    at:

       http://wwwstats.net.wisc.edu

    which show traffic in and out through a peering point or network
    border. The `SubNetIO' report updates RRD files for each of the
    subnets that you specify (so that you can produce graphs of
    `CampusIO' by subnet).

    The idea behind the distinct report modules is that users will
    be able to write new reports that are either derived-classes
    from `CampusIO' or altogether new ones. For instance, one may
    wish to write a report module called `Abuse' which would send
    email when it detected potentially abusive things going on, like
    Denial-of-Service attacks and various scans.

    FlowScan is freely-available under the GPL, the GNU General
    Public License.

Use the Mailing List
    Please help me to help you. It is, unfortunately, not uncommon
    for one to have questions or problems while installing FlowScan.
    Please do not send email about such things to my personal email
    address, but instead check the FlowScan mailing list archive,
    and join the FlowScan mailing list. Information about the
    FlowScan mailing lists can be found at:

       http://net.doit.wisc.edu/~plonka/FlowScan/#Mailing_Lists

    By reading and participating in the list, you will be helping me
    to use my time effectively so that others will benefit from
    questions answered and issues raised.

    The mailing lists' archives are available at:

       http://net.doit.wisc.edu/~plonka/list/flowscan

    and:

       http://net.doit.wisc.edu/~plonka/list/flowscan-announce

Upgrading
    First-time FlowScan users should skip to the section on "Initial
    Install Requirements", below.

    If you have previously installed and properly configured
    `FlowScan-1.005', you need only perform a subset of the steps
    that one would normally have to perform for an initial
    installation.

    This release of FlowScan uses more memory than previous
    releases. That is, the `flowscan' process will grow to a larger
    size than that in `FlowScan-1.005'. In my recent experience
    while testing this release, the `flowscan' process size to
    approximately 128MB when I use the new experimental
    `BGPDumpFile' option to produce "Top" reports by ASN. This is
    hopefully understandable since `flowscan' is carrying a full
    internet routing table when configured in this way. The memory
    requirements are significantly lessened if you do not use the
    `BGPDumpFile' option. The `flowscan' process' size is also a
    function of the number of active hosts in your network.

  Software Upgrade Requirements

    * Upgrading perl Modules
        Upgrade the `Cflow' perl module to `Cflow-1.030' or later
        for improved performance. Install `HTML::Table' in case you
        want to produce the new "Top Talkers" reports. Details on
        how to obtain and install these modules can be found in the
        section on "Software Requirements", below.

    * Upgrading FlowScan
        Of course, when upgrading you will need to obtain the
        current FlowScan. When you run configure, you should specify
        the same value with `--prefix' that you did when installing
        your existing FlowScan, e.g. /var/local/flows, or wherever
        your time-stamped raw flow files are currently being written
        by `cflowd'.

  Configuring FlowScan when Upgrading

    There is now POD documentation provided with the CampusIO and
    SubNetIO reports. Please use that as the definitive reference on
    configuration options for those reports, e.g.:

       $ cd bin
       $ perldoc CampusIO

    Here are a few things that changed regarding the FlowScan
    configuration:

    Upgrading CampusIO and/or SubNetIO Configuration Files
        There are new `TopN' and `ReportPrefixFormat' directives for
        `CampusIO' and `SubNetIO'. These directives enable the
        production of "Top Talker" reports. Furthermore there are
        new experimental `BGPDumpFile' and `ASNFile' options
        `CampusIO' which are used to produce "Top" reports by
        Autonomous System. You will need access a Cisco carrying a
        full BGP routing table to produce such reports. See the
        CampusIO configuration documentation for more info about
        configuring this feature. If you have trouble with it,
        remember that it is experimental, so please join the
        discussion in the mailing list.

        Secondly, the Napster_subnets.boulder has changed
        significantly since that provided with FlowScan-1.005. If
        you have FlowScan configured to measure Napster traffic,
        replace your old Napster_subnets.boulder with the one from
        the newer distribution:

           $ cp cf/Napster_subnets.boulder $PREFIX/bin/Napster_subnets.boulder

    Upgrading your RRD Files
        If you are upgrading, it is necessary to add two new Data
        Sources to the some of your existing RRD files. Before
        running flowscan, backup your RRD files, e.g.:

           $ cd $prefix/graphs
           $ tar cf saved_rrd_files.tar *.rrd

        then do this:

           $ cd $prefix/graphs
           $ ../bin/add_txrx total.rrd [1-9]*.*.*.*_*.rrd

  Generating Graphs after Upgrading

    A number of new features have been added to the graphs.mf
    template Makefile. Some of these are described below in the
    section on "Supplied Graphs". You may wish to copy graphs.mf to
    your graphs sub-directory.

    While it is not required, I highly recommend installing
    `RRGrapher' if you want to produce other graphs. It is
    referenced below in the section on "Custom Graphs".

  Done Upgrading

    That should be it for upgrading!

Initial Install Requirements
  Hardware Requirements

    * Cisco routers
        If you don't have Cisco at your border, you're probably
        barking up the wrong tree with this package. Also, FlowScan
        currently requires that your IOS version supports NetFlow
        version 5. Try this command on your router if you are
        unsure:

           ip flow-export version ?

    * a GNU/Linux or Unix machine
        If you have a trivial amount of traffic being exported to
        cflowd, such as a T1's worth, perhaps any old machine will
        do.

        However, if you want to process a fair amount of traffic
        (e.g. at ~OC-3 rates) you'll want a *fast* machine.

        I've run FlowScan on a SPARC Ultra-30 w/256MB running
        Solaris 2.6, a Dell Precision 610 (dual Pentium III,
        2x450Mhz) w/128MB running Debian Linux 2.1, and most
        recenlty a dual PIII Dell server, 2x600Mhz, w/256MB running
        Debian Linux 2.2r2. The Intel machines are definitely
        preferably in the sense that `flowscan' processes flows in
        about 40% of the time that it took the SPARC. (The main
        `flowscan' script itself is currently single-threaded.)

        In an early performance test of mine, using 24 hours of
        flows from our peering router here at UW-Madison, here's the
        comparison of their ave. time to process 5 minutes of flows:

           SPARC - 284 sec
           Intel - 111 sec

        Note that it is important that flowscan doesn't take longer
        to process the flows than it does for your network's
        activity and exporting Cisco routers to produce the flows.
        So, you want to keep the time to process 5 minutes of flows
        under 300 seconds on average.

        My recent testing has indicated that 600-850MHz PIII
        machines can usually process 3000-4000 flows per second, if
        `flowscan' doesn't have to compete with too many other
        processes.

    * Disk Space
        I recommend devoting a file-system to cflowd and FlowScan.
        Both require disk space and the amount depends upon a number
        of things:

    * The rate of flows being exported and collected
    * The rate at which FlowScan is able to process (and remove) those files
    * Whether or not you have configured FlowScan to "save" flow files
    * The number of hours after which you remove `gzip(1)'ped flow files
        To find the characteristics of your environment, you'll just
        have to run the patched cflowd for a little while to see
        what you get.

        Early in this project (c. 1999), we were usually collecting
        about 150-300,000 flows from our peering router every 5
        minutes. Recently, our 5-minute flow files average ~15 to 20
        MB in size.

        During a recent inbound Denial-of-Service attack consisting
        of 40-byte TCP SYN packets with random source addresses and
        port numbers, I've seen a single "5-minute" flow file
        greater than 500MB! Even on our fast machine, that single
        file took hours to process.

        Surely YMMV, currently a 35GB file-system allows us to
        preserve `gzip(1)'ped flow files for about 2 weeks.

    * Network Interface Card
        Regarding the host machine configuration, consider the
        amount of traffic that may be exported from your Cisco(s) to
        your collector machine if you have enabled `ip route-cache
        flow' on very many fast interfaces. With lots of exported
        flow data (e.g. 15-20 MB of raw flow file data every 5
        minutes) and only a 10 Mb/s ethernet NIC, I found that the
        host was dropping some of the incoming UDP packets, even
        though the rate of incoming flows was less than 2 Mb/s. This
        was evidenced by a constantly-increasing number of
        `udpInOverflows' in the `netstat -s' output under Solaris. I
        addressed this by reconfiguring my hosts with a 100 Mb/s
        fast ethernet NIC or 155 Mb/s OC-3 ATM LANE interface and
        have not seen that problem since. Of course, one should
        assure that the requisite bandwidth is available along the
        full path between the exporting Cisco(s) and the collecting
        host.

  Software Requirements

    The packages and perl modules required by FlowScan are numerous.
    Their presence or absence will be detected by FlowScan's
    configure script but you'll save yourself some frustration by
    getting ahead of the game by collecting and installing them
    first. Below, I've attempted to present them in a reasonable
    order in which to obtain, build, and install them.

    * arts++
        arts++ is required by cflowd and is available at:

           ftp://ftp.caida.org/pub/arts++/

        As of arts++-1-1-a5, the arts++ build appears to require GNU
        make 3.79 because its Makefiles use glob for header
        dependencies, e.g. "*.hh". From my cursory look at the GNU
        make ChangeLog, perhaps any version >= 3.78.90 will suffice.
        Also there may be trouble if you don't have flex headers
        installed in your "system" include directory, such as
        "/usr/include", even though "configure.in" appears to be
        trying to handle this situation. Since mine were in the
        "local" include directory, I hand-tweaked the
        classes/src/Makefile's ".cc.o" default rule to include that
        directory as well.

    * cflowd patch
        My patches are available at:

           http://net.doit.wisc.edu/~plonka/cflowd/?M=D

        Obtain the patch or patches which apply to the version of
        cflowd that you intend to run and apply it to cflowd before
        building cflowd below.

    * cflowd
        cflowd itself is available at:

           http://www.caida.org/tools/measurement/cflowd/
           ftp://ftp.caida.org/pub/cflowd/

        In my experience with building cflowd, you're the most
        likely to have success in a GNU development environment such
        as that provided with GNU/Linux or FreeBSD.

        I have not had problems building the patched `cflowd-2-1-a9'
        or `cflowd-2-1-a6' under Debian Linux 2.2.

        I've also managed to build the patched cflowd-2-1-a6 with
        gcc-2.95.2 and binutils-2.9.1 on a sparc-sun-solaris2.6
        machine with GNU make 3.79 and flex-2.5.4.

        As of cflowd-2-1-a6, beware that during the build may pause
        for minutes while as(1) uses lots of CPU and memory to
        building "CflowdCisco.o". This is apparenly `normal'. Also,
        the build appears to be subtley reliant on GNU ld(1), which
        is available in the GNU "binutils" package. (I was unable to
        build cflowd-2-1-a6 with the sparc-sun-solaris2.6
        "/usr/ccs/bin/ld" although earlier cflowd releases built
        fine with it.)

    * perl 5
        If you don't have this already, you're probably way over
        your head, but anyway, check out the Comprehensive Perl
        Archive Network (CPAN):

           http://www.cpan.org/

        and:

           http://www.perl.com/

        I've tested with perl 5.004, 5.005, and 5.6.0. If you'd like
        to upgrade to perl 5.6.0 you can install it thusly:

           # perl -MCPAN -e shell
           cpan> install G/GS/GSAR/perl-5.6.0.tar.gz

        However, I suggest you don't install it in the same place as
        your existing `perl'.

    * Korn shell
        `ksh' is used as the `SHELL' in the Makefile for the graphs.
        `pdksh' works fine too. If for some reason you don't already
        have `ksh', check out:

           http://www.kornshell.com/

        or:

           http://www.math.mun.ca/~michael/pdksh/

        If you're using GNU/Linux, `pdksh' is available as an
        optional binary package for various distributions.

    * RRDTOOL
        This package is available at:

           http://ee-staff.ethz.ch/~oetiker/webtools/rrdtool/

        I recommend that you install `rrdtool' from source, even if
        it is available as an optional binary package for operating
        system distribution. This is because FlowScan expects that
        you've built and installed RRDTOOL something like this:

           $ ./configure --enable-shared
           $ make install site-perl-install

        That last bit is important, since it makes the `rrdtool'
        perl modules available to all perl scripts.

    * Perl Modules
    * `RRDs'
            This is the shared-library perl module supplied with
            `rrdtool'. (See above.)

    * `Boulder'
            The Boulder distribution includes the Boulder::Stream
            module and its prerequisites. They are available on CPAN
            in the "Boulder" distribution.

            You can install them using the CPAN shell like this:

               # perl -MCPAN -e shell
               cpan> install Boulder::Stream

            If you want to fetch it manually you can probably find
            it at:

               http://search.cpan.org/search?dist=Boulder

            I've tested with the modules supplied in the Boulder-
            1.18 distribution and also those in the old
            "boulder.tar.gz" distribution.

    * `ConfigReader::DirectiveStyle'
            The ConfigReader package is available on CPAN. You can
            install it using the CPAN shell like this:

               # perl -MCPAN -e shell
               cpan> install ConfigReader::DirectiveStyle

            If you want to fetch it manually you can probably find
            it at:

               http://search.cpan.org/search?dist=ConfigReader

            I'm using ConfigReader-0.5.

    * `HTML::Table'
            The HTML::Table package is available on CPAN. You can
            install it using the CPAN shell like this:

               # perl -MCPAN -e shell
               cpan> install HTML::Table

            If you want to fetch it manually you can probably find
            it at:

               http://search.cpan.org/search?dist=HTML-Table

    * `Net::Patricia'
            This is a new module which I have uploaded to PAUSE, but
            it not have entered CPAN yet.

            You can try to install it using the CPAN shell like
            this:

               # perl -MCPAN -e shell
               cpan> install Net::Patricia

            If `Net::Patricia' is not found on CPAN, you can obtain
            it here:

               http://net.doit.wisc.edu/~plonka/Net-Patricia/

    * `Cflow'
            This perl module is used by FlowScan to read the raw
            flow files written by cflowd. It is available at:

               http://net.doit.wisc.edu/~plonka/Cflow/

            You'll need Cflow-1.024 or greater.

    * FlowScan
            This package is available at:

               http://net.doit.wisc.edu/~plonka/FlowScan/

Configuring FlowScan Prerequisites
  Choose a User to Run cflowd and FlowScan

    I recommend that you create a user just for the purpose of
    running these utilities so that all directory permissions and
    created file permissions are consistent. You may find this
    useful especially if you have multiple network engineers
    accessing the flows.

    I suggest that the FlowScan `--prefix' directory be owned by an
    appropriate user and group, and that the permissions allow write
    by other members of the group. Also, turn on the set-group-id
    bit on the directory so that newly created files (such as the
    flow files and log file) will be owned by that group as well,
    e.g.:

       user$ chmod g+ws $PREFIX

  Configuring Your Host

    The current FlowScan graphing stuff likes your machine to have
    the `80/tcp' service to be called `http'. Try running this
    command:

       $ perl -le "print scalar(getservbyport(80, 'tcp'))"

    You can continue with the next step if this command prints
    `http'. However, if it prints some other value, such as `www',
    then I suggest you modify your /etc/services file so that the
    line containing `80/tcp' looks something like this:

       http             80/tcp    www www-http         #World Wide Web HTTP

    Be sure to leave the old name such as `www' as an "alias", like
    I've shown here. This will reduce the risk of breaking existing
    applications which may refer to the service by that name. If you
    decide not to modify the service name in this way, FlowScan
    should still work, but you'll be on your own when it comes to
    producing graphs.

  Configuring Your Ciscos

    First and foremost, to get useful flow information from your
    Cisco, you'll need to enable flow-switching on the appropriate
    ingress interfaces using this interface-level configuration
    statement:

       ip route-cache flow

    Also, I suggest that you export from your Cisco like this:

       ip flow-export version 5 peer-as
       ip flow-export destination 10.0.0.1 2055

    Of course the IP address and port are determined by your
    cflowd.conf. To help ensure that flows are exported in a timely
    fashion, I suggest you also do this if your IOS version supports
    it:

       ip flow-cache timeout active 1

    Some IOS versions, e.g. 12.0(9), use this syntax instead:

       ip flow-cache active-timeout 1

    unless you've specified something such as `downward-compatible-
    config 11.2'.

    Lastly, in complicated environments, choosing which particular
    interfaces should have `ip route-cache flow' enabled is somewhat
    difficult. For FlowScan, one usually wants it enabled for any
    interface that is an ingress point for traffic that is from
    inside to outside or vice-versa. You probably don't want flow-
    switching enabled for interfaces that carry policy-routed
    traffic, such as that being redirected transparently to a web
    cache. Otherwise, FlowScan could count the same traffic twice
    because of multiple flows being reported for what was
    essentially the same traffic making multiple passes through a
    border router. E.g. user-to-webcache, webcache-to-outside world
    (on behalf of that user).

  Configuring cflowd

    This document does not attempt to explain cflowd. There is good
    documentation provided with that package.

    As for the tweaks necessary to get cflowd to play well with
    FlowScan, hopefully, an example is worth a thousand words.

    My cflowd.conf file looks like this:

       OPTIONS {
         LOGFACILITY:          local6
         TCPCOLLECTPORT:       2056
         TABLESOCKFILE:        /home/whomever/cflowd/etc/cflowdtable.socket
         FLOWDIR:              /var/local/flows
         FLOWFILELEN:          1000000
         NUMFLOWFILES:         10
         MINLOGMISSED:         300
       }
       CISCOEXPORTER {
         HOST:         10.0.0.10
         ADDRESSES:    { 10.42.42.10,
                       }
         CFDATAPORT:   2055
       #  COLLECT:      { flows }
       }
       COLLECTOR {
         HOST:         127.0.0.1
         AUTH:         none
       }

    And I invoke the *patched* cflowd like this:

       user$ cflowd -s 300 -O 0 -m /path/to/cflowd.conf

    Those options cause a flow file to be "dropped" every 5 minutes,
    skipping flows with an output interface of zero unless they are
    multicast flows. Once you have this working, your ready to
    continue.

Configuring FlowScan
  Configure and Install

    Do not use the same `--prefix' value as might for other
    packages!

    I.e. don't use /usr/local or a similar directory in which other
    things are installed. This prefix should be the directory where
    the patched cflowd has been configured to write flow files.

    A good way to avoid doing something dumb here is to not run
    FlowScan's `configure' nor `make' as root.

       user$ ./configure --help # note --with-... options

    e.g.:

       user$ ./configure --prefix=/var/local/flows
       user$ make
       user$ make -n install
       user$ make install

    By the way, in the above commands, all is OK if make says
    "`Nothing to be done for `target''". As long as `make' completes
    without an error, all is OK.

    Subsequently in this document the "prefix" directory will be
    referred to as the "`--prefix' diretory" or using the
    environment variable `$PREFIX'. FlowScan does not require or use
    this environment variable, it's just a documentation convention
    so you know to use the directory which you passed as with `--
    prefix'.

  Create the Output Directory

    The `OutputDir' is where the `.rrd' files and graphs will
    reside. As the chosen FlowScan user do:

      $ PREFIX=/var/local/flows
      $ mkdir -p $PREFIX/graphs

    Then, when you edit the `.cf' files below, be sure to specify
    this using the `OutputDir' directive.

  FlowScan Configuration Files

    The FlowScan Package ships with sample configuration files in
    the `cf' sub-directory of the distribution. During initial
    configuration you will copy and sometimes modify these sample
    files to match your network environent and your purposes.

    FlowScan looks for its configuration files in its `bin'
    directory - i.e. the directory in which the `flowscan' perl
    script *and* FlowScan report modules are installed. I don't
    really like this, but that's the way it is for now. Forgive me.

    FlowScan currently uses two kinds of cofiguration files:

    1 Directive`-s'tyle configuration files, with the `.cf' extension
        This format should be relatively self-explanatory based on
        the sample files referenced below. The directives are
        documented in comments within those sample configuration
        files.

        A number of the directorives have paths to directory entries
        as their values. One has a choice of configuring these as
        either relative or absolute paths. The samples configuration
        files ship with relative path specifications to minimize the
        changes a new user must make. However, in this
        configuration, it is imperitive that `flowscan' be run in
        the `--prefix' directory if these relative paths are used.

    2 "Boulder IO" format files, with the `.boulder' extension
        I've chosen Boulder IO's "semantic free data interchange
        format" to use for related projects, and since this is the
        format in which our subnet definitions were available, I
        continued to use it.

        If you're new to "Boulder IO", the examples referenced below
        should be sufficient. Remember that lines containing just
        `=' are record seperators.

        For complete information on this format, do:

           $ perldoc Boulder # or "perldoc bolder" if that fails

    Here's a step-by-step guide to installing, reviewing, and
    editing the FlowScan configuration files:

    * Copy and Edit flowscan.cf
          $ cp cf/flowscan.cf $PREFIX/bin
          $ chmod u+w $PREFIX/bin/flowscan.cf
          $ # edit $PREFIX/bin/flowscan.cf

    * Decide which FlowScan Reports to Run
        The FlowScan package contains the `CampusIO' and `SubNetIO'
        reports. These two reports are mutually exclusive -
        `SubNetIO' does everything that `CampusIO' does, and more.

        Initially, in flowscan.cf I strongly suggest you configure:

           ReportClasses CampusIO

        rather than:

           ReportClasses SubNetIO

        The `CampusIO' report class is simpler than `SubNetIO',
        requires less configuration, and is less CPU/processing
        intensive. Once you have the `CampusIO' stuff working, you
        can always go back and configure `flowscan' to use
        `SubNetIO' instead.

        There is POD documentation provided with the `CampusIO' and
        `SubNetIO' reports. Please use that as the definitive
        reference on configuration options for those reports, e.g.:

           $ cd bin
           $ perldoc CampusIO

    * Copy and Edit CampusIO.cf
        Copy the template to the bin directory. Adjust the values
        using the required and optional configuration directives
        documented there-in.

        The most important thing to consider configuring in
        CampusIO.cf is the method by which `CampusIO' should
        identify outbound flows. In order of preference, you should
        define `NextHops', or `OutputIfIndexes', or neither. Beware
        that if you define neither, CampusIO will resort to using
        the flow destination address to determine whether or not the
        flow is outbound. This can be troublesome if you do not
        accurately define your local networks (below), since flows
        forwarded to any non-local addresses will be considered
        outbound. If possible, it's best to define the list of
        `NextHops' to which you know your outbound traffic is
        forwarded.

        For most purposes, the default values for the rest of the
        `CampusIO' directives should suffice. For advanced users
        that export from multiple Ciscos to the same cflowd/FlowScan
        machine, it is also very important to configure
        `LocalNextHops'.

    * Copy and Edit local_nets.boulder
        Copy the template to the bin directory. This file should be
        referenced in CampusIO.cf by the `LocalSubnetFiles'
        directive.

        The local_nets.boulder file must contain a list of the
        networks or subnets within your organization. It is
        imperative that this file is maintained accurately since
        flowscan will use this to determine whether a given flow
        represents inbound traffic.

        You should probably specify the networks/subnets in as terse
        a way as possible. That is, if you have two adjacent subnets
        that can be coallesced into one specification, do so. (This
        is differnet than the similarly formatted
        our_subnets.boulder file mentioned below.)

        The format of an entry is:

           SUBNET=10.0.0.0/8
           [TAG=value]
           [...]

        Technically, `SUBNET' is the only tag required in each
        record. You may find it useful to add other tags such as
        `DESCRIPTION' for documentation purposes. Entries are
        seperated by a line containing a single `='.

        FlowScan identifies outbound flows based on the list of
        nexthop addresses that you'll set up below.

    * Copy and Edit Napster_subnets.boulder (*if* referenced in CampusIO.cf)
        Note: if you do not wish to have `CampusIO' attempt to
        identify Napster traffic, be sure to comment out all Napster
        related option in CampusIO.cf.

        Copy the template to the bin directory from which you will
        be running `flowscan'. The supplied content seems to work
        well as of this writing (Mar 10, 2000). No warranties.
        Please let me know if you have updates regarding Napster IP
        address usage, protocol, and/or port usage.

        The file Napster_subnets.boulder should contain a list of
        the networks/subnets in use by Napster, i.e. `napster.com'.

        As of this writing, more info on Napster can be found at:

           http://napster.cjb.net/
           http://opennap.sourceforge.net/napster.txt
           http://david.weekly.org/code/napster-proxy.php3

    * Copy and Edit SubNetIO.cf (*if* you have selected it in your `ReportClasses')
        Copy the template to the bin directory from which you will
        be running flowscan. Adjust the values using the required
        and optional configuration directives documented there-in.
        For most purposes, the default values should suffice.

    * Copy and Edit our_subnets.boulder (*if* you use `ReportClasses SubNetIO')
        Copy the template to the bin directory.

        This file is used by the `SubNetIO' report class, and
        therefore is only necessary if you have defined
        `ReportClasses SubNetIO' rather than `ReportClasses
        CampusIO'.

        The file our_subnets.boulder should contain a list of the
        subnets on which you'd like to gather I/O statistics.

        You should format this file like the aforementioned
        local_nets.boulder file. However, the `SUBNET' tags and
        values in this file should be listed exactly as you use them
        in your network: one record for each subnet. So, if you have
        two subnets, with different purposes, they should have
        seperate entries even if they are numerically adjacent. This
        will enable you to report on each of those user populations
        independently. For instance:

           SUBNET=10.0.1.0/24
           DESCRIPTION=power user subnet
           =
           SUBNET=10.0.2.0/24
           DESCRIPTION=luser subnet

  Preserving "Old" Flow Files

    If you'd like to have FlowScan save your flow files, make a sub-
    directory named saved in the directory where flowscan has been
    configured to look for flow files. This has been specified with
    the `FlowFileGlob' directive in flowscan.cf and is usually the
    same directory that is specified using the `FLOWDIR' directive
    in your cflowd.conf.

    If you do this, flowscan will move each flow file to that saved
    sub-directory after processing it. (Otherwise it would simply
    remove them.) e.g.:

       $ mkdir $PREFIX/saved
       $ touch $PREFIX/saved/.gzip_lock

    The .gzip_lock file created by this command is used as a lock
    file to ensure that only one cron job at a time.

    Be sure to set up a crontab entry as is mentioned below in the
    section on "Final Setup". I.e. don't complain to the author if
    you're saving flows and your file-system fills up ;^).

Testing FlowScan
    Once you have the patched cflowd running with the `-s 300'
    option, and it has written at least one time-stamped flow file
    (i.e. other than flows.current), try this:

      $ cd /dir/containing/your/time-stamped/raw/flow/files
      $ flowscan

    The output should appear as something like this:

       Loading "bin/Napster_subnets.boulder" ...
       Loading "bin/local_nets.boulder" ...
       2000/03/20 17:01:04 working on file flows.20000320_16:57:22...
       2000/03/20 17:07:38 flowscan-1.013 CampusIO: Cflow::find took 394 wallclock secs (350.03 usr +  0.52 sys = 350.55 CPU) for 23610455 flow file bytes, flow hit ratio: 254413/429281
       2000/03/20 17:07:41 flowscan-1.013 CampusIO: report took  3 wallclock secs ( 0.44 usr +  0.04 sys =  0.48 CPU)
       sleep 300...

    At this point, the RRD files have been created and updated as
    the flow files are processed. If not, you should use the
    diagnostic warning and error messages or the perl debugger
    (`perl -d flowscan') to determine what is wrong.

    Look at the above output carefully. It is imperative that the
    number of seconds that `Cflow::find took' not usually approach
    nor exceed 300. If, as in the example above, your log messages
    indicate that it took more than 300 seconds, FlowScan will not
    be able to keep up with the flows being collected on this
    machine (if the given flow file is representative). If the total
    of usr + sys CPU seconds totals more than 300 seconds, than this
    machine is not even capable of running FlowScan fast enough, and
    you'll need to run it on a faster machine (or tweak the code,
    rewrite in C, or mess with process priorities using nice(1),
    etc.)

Performance Problems?
    Here are some hints on getting the most out of your hardware if
    you find that FlowScan is processing 300 seconds of flows in
    less an averave of 300 CPU seconds or less, but not 300 seconds
    of real time; i.e. the `flowscan' process is not being scheduled
    to run often enough because of context switching or because of
    its competing for CPU with too many other processes.

    On a 2 processor Intell PIII, to keep `flowscan' from having to
    compete with other processes for CPU, I have recently had good
    luck with setting the `flowscan' process' `nice(1)' value to -
    20.

    Furthermore, I applied this experimental patch to the Linux
    2.2.18pre21 kernel:

       http://isunix.it.ilstu.edu/~thockin/pset/

    This patch enables users to determine which processor or set of
    processors a process may run on. Once applied, you can reserve
    the 2nd processor solely for use by `flowscan':

       root# mpadmin -r 1

    Then launch `flowscan' on processor number 1:

       root# /usr/bin/nice --20 /usr/bin/runon 1 /usr/bin/su - username -c '/usr/bin/nohup /var/local/flows/bin/flowscan -v' >> /var/local/flows/flowscan.log 2>&1 </dev/null &'

    This configuration has yielded the best ratio of CPU to real
    seconds that I have seen - nearly 1 to 1.

Final Setup
    Once you feel that `flowscan' is working correctly, you can set
    it (and `cflowd') to start up at system boot time. Sample `rc'
    scripts for Solaris and Linux are supplied in the rc sub-
    directory of this distribution. You may have to edit these
    scripts depending on your ps(1) flavor and where various
    commands have been installed on your system.

    Also, if you're saving your flow files, you should set up
    crontab entries to handle the "old" flows. I use one crontab
    entry to `gzip(1)' recently processed files, and another to
    delete the files older than a given number of hours. The "right"
    number of hours is a function of your file-system size and the
    rate of flows being exported/collected. See the example/crontab
    file.

Generating Graphs
  Supplied Graphs

    To generate graphs, try the graphs.mf Makefile:

      $ cp graphs.mf $PREFIX/graphs/Makefile
      $ cd $PREFIX/graphs
      $ make

    This should produce the "Campus I/O by IP Protocol" and "Well
    Known Services" graphs in PNG files. GIF files may be produced
    using the `filetype' option mentioned below.

    If this command fails to produce those graphs, it is likely that
    some of the requisite `.rrd' files are missing, i.e. they have
    not yet been created by FlowScan, such as http_dst.rrd. If this
    is the case, it is probably because you skipped the
    configuration of /etc/services in the section on "Configuring
    Your Host". Stop `flowscan', rename your www_*.rrd files to
    http_*.rrd, modify /etc/services, and restart `flowscan'.

    Alternatively, you may copy and customize the graphs.mf Makefile
    to remove references to the missing or misnamed `.rrd' files for
    those targets. Also, you could produce your graphs using a
    graphing tool such as RRGrapher mentioned below in the section
    on "Custom Graphs".

    Note that the graphs.mf template Makefile has options to specify
    such things as the range of time, graph height and width, and
    output file type. Usage:

       make -f graphs.mf [filetype=<png|gif>] [width=x] [height=y] [ioheight=y+n] [hours=h] [tag=_tagval] [events=public_events.txt] [organization='Foobar U - Springfield Campus']

    as in:

       $ make -f graphs.mf filetype=gif height=400 hours=24 io_services_bits.gif

  Adding Events to Graphs

    There is a new graphing feature which allows you to specify
    events that should be displayed in your graphs. These events are
    simply a list of points in time at which something of interest
    occurred.

    For instance, one could create a plain text file in the graphs
    directory called events.txt containing these lines:

       2001/02/10 1538 added support for events to FlowScan graphs
       2001/02/12 1601 allowed the events file to be named on make command line

    Then to generate the graphs with those events included one might
    run:

       $ make -f graphs.mf events=events.txt

    This feature was implemented using a new script called
    event2vrule that is supplied with FlowScan. This script is meant
    to be used as a "wrapper" for running rrdtool(1), similarly to
    how one might run nohup(1). E.g.:

       $ event2vrule -h 48 events.txt rrdtool graph -s -48h ...

    That command will cause these `VRULE' arguments to be passed to
    rrdtool, at the end of the argument list:

       COMMENT:\n
       VRULE:981841080#ff0000:2001/02/10 1538 added support for events to FlowScan graphs
       COMMENT:\n
       VRULE:982015260#ff0000:2001/02/12 1601 allowed the events file to be named on make command line
       COMMENT:\n

  Custom Graphs

    Creation of other graphs will require the use of a tool such as
    RRGrapher or knowledge of RRDTOOL. RRGrapher, my Graph
    Construction Set for RRDTOOL is available at:

       http://net.doit.wisc.edu/~plonka/RRGrapher/

    For other custom graphs, if you use the supplied graphs.mf
    Makefile, you can use the examples there in to see how to build
    "Campus I/O by Network" and "AS to AS" graphs. The examples use
    UW-Madison network numbers, names of with which we peer and
    such, so it will be non-trivial for you to customize them, but
    at least there's an example.

    Currently, RRD files for the configured `ASPairs' contain a `:'
    in the file name. This is apparently a no-no with RRDTOOL since,
    although it allows you create files with these names, it doesn't
    let you graphs using them because of how the API uses `:' to
    seperate arguments.

    For the time being, if you want to graph AS information, you
    must manually create symbolic links in your graphs sub-dir. i.e.

       $ cd graphs
       $ ln -s 0:42.rrd Us2Them.rrd
       $ ln -s 42:0.rrd Them2Us.rrd

    A reminder for me to fix this is in the TODO list.

  Future Directions for Graphs

    The current Makefile-based graphing, while coherent, is
    cumbersome at best. I find that the verbosity and complexity of
    adding new graph targets to the Makefile makes my brain hurt.

    Other RRDTOOL front-ends that produce graphs should be able to
    work with FlowScan-generated `.rrd' files, so there's hope.

Copyright and Disclaimer
        Note that this document is provided `as is'. The information
        in it is not warranted to be correct. Use it at your own
        risk.

           Copyright (c) 2000-2001 Dave Plonka <plonka@doit.wisc.edu>.
           All rights reserved.

        This document may be reproduced and distributed in its
        entirety (including this authorship, copyright, and
        permission notice), provided that no charge is made for the
        document itself.

