grep(1)-like utility for raw flow files
flowdumper [-h] [-v] [-s|S|r|R] [-a|n] [[-I expr] -e expr [-E expr]] [-c] [-B file] [-o output_file] [flow_file [...]]
but usually just:
flowdumper [-s] -e expr flow_file [...]
grep(1)-like utility for selecting and processing flows
from cflowd or flow-tools raw flow files. The selection criteria are
specified by using the -e option described below.
flowdumper's primary features are the ability to:
sed(1).
file(s) or
standard input, and producing filtered raw flow output on standard output.
This is similar to how grep(1) is often used on text files.
-e
expression are those made available by the Cflow module when used like
this:
use Cflow qw(:flowvars :tcpflags :icmptypes :icmpcodes);
See the Cflow perl documentation for full details on these values (i.e. ``perldoc Cflow''.)
Most perl syntax is allowed in the expressions specified with the -e,
-I, and -E options. See the perl man pages for full details on operators (``man
perlop'') and functions (``man perlfunc'') available for use in those
expressions.
If run with no arguments, filters standard input to standard output.
The options and their arguments, roughly in order of usefulness, are:
mnemonic: 'h'elp
implied if -e is not specified
mnemonic: 'a'll
mnemonic: 'e'xpression
mnemonic: 'c'ount
-n
mnemonic: 's'hort
ignored with -n
mnemonic: 'r'aw
requires -e, ignored with -n, useful with -p
mnemonic: 'R'epack raw
mnemonic: like ``perl -n'' or ``sed -n''
printf(3) string
conversion specifier can be used within the output_file value (such as
``/tmp/%s.txt'') to make the output file name a function of the input file
basename.
mneomic: 'o'utput file
ignored with -n
mnemonic: 'S'hort
mnemonic: 'v'erbose
-v'')
mnemonic: 'V'ery verbose
practically useless without -e
mnemonic: 'I'nitial expression
practically useless without -e
mnemonic: 'E'ND expression
In your optional expression, you can now refer to these variables:
$dst_as_path_arrayref $dst_origin_as $dst_peer_as $src_as_path_arrayref $src_origin_as $src_peer_as
which will cause a lookup. Their values are undefined if the lookup fails.
mnemonic: 'B'GP dump file
10.42.69.0/24 -> 10.69.42.0/24 ...
When specifying this option, you can, and should at some point, call the ENCODE subroutine in your expressions to have it encode the IP address flowvars such as $Cflow::exporter, $Cflow::srcaddr, $Cflow::dstaddr, and $Cflow::nexthop.
mnemonic: 'p'refixes
$ flowdumper -a flows.* |less
Print all the UDP flows to another file using the raw binary flow format:
$ flowdumper -re '17 == $protocol' flows.current > udp_flows.current
Print all TCP flows which have the SYN bit set in the TCP flags:
$ flowdumper -se '6 == $protocol && ($TH_SYN & $tcp_flags)' flows.*
Print the first 10 flows to another file using the raw binary flow format:
$ flowdumper -I '$n = 10' -re '$n-- or exit' flows.*0 > head.cflow
Print all flows with the start and end time using a two-line format:
$ flowdumper -se 'print scalar(localtime($startime)), "\n"' flows.*
Print all flows with the specified source address using a short, single-line format:
$ flowdumper -se '"10.42.42.42" eq $srcip' flows.*
Do the same thing in a quicker, but less obvious, way:
$ flowdumper -I '
use Socket;
$addr = unpack("N", Socket::inet_aton("10.42.42.42"));
' -se '$addr == $srcaddr' flows.*
(This latter method runs quicker because inet_aton(3) is only
called once, instead of once per flow.)
Print all flows with a source address within the specifed network/subnet:
$ flowdumper \
-I 'use Socket;
$mask = unpack("N", Socket::inet_aton("10.42.0.0"));
$width = 16' \
-se '$mask == ((0xffffffff << (32-$width)) & $srcaddr)' flows.*
Print all flows where either the source or the destination address, but not both, is within the specified set of networks or subnets:
$ flowdumper \
-I 'use Net::Patricia;
$pt = Net::Patricia->new;
map { $pt->add_string($_, 1) } qw( 10.42.0.0/16
10.69.0.0/16 )' \
-se '1 == ($pt->match_integer($srcaddr) +
$pt->match_integer($dstaddr))' flows.*
Count the total number of ``talkers'' (unique source host addresses) by
piping them to sort(1) and wc(1) to count them:
$ flowdumper \
-I 'use Net::Patricia;
$pt = Net::Patricia->new;
map { $pt->add_string($_, 1) } qw( 10.42.0.0/16
10.69.0.0/16 )' \
-ne '$pt->match_integer($srcaddr) and print "$srcip\n"' flows.* \
|sort -u |wc -l
Count the total number of ``talkers'' (unique source host addresses) that are within a the specified networks or subnets:
$ flowdumper \
-I 'use Net::Patricia;
$pt = new Net::Patricia;
map { $pt->add_string($_, 1) } qw( 10.42.0.0/16
10.69.0.0/16 );
$talkers = new Net::Patricia' \
-ne '$pt->match_integer($srcaddr) &&
($talkers->match_integer($srcaddr) or
$talkers->add_string($srcip, 1))' \
-E 'printf("%d\n", $talkers->climb( sub { 1 } ))' flows.*
(For large numbers of flows, this latter method is quicker because it populates a Net::Patricia trie with the unique addresses and counts the resulting nodes rather than having to print them to standard output and then having to sort them to determine how many are unique.)
Select the TCP flows and ``ENCODE'' the IP addresses according to the prefix encodings specified in ``prefix_encodings.txt'':
$ flowdumper -p prefix_encodings.txt -se '6 == $protocol && ENCODE'
Produce a new raw flow file with the IP addresses ENCODEd according to the prefix encodings specified in ``prefix_encodings.txt'':
$ flowdumper -p prefix_encodings.txt -Re 'ENCODE' flows > flows.enc
Produce a set of raw flow files that have the $src_as and
$dst_as origin AS values filled in based upon a lookup in
externally-specified routing table (in the file ``router.bgp'') and have
the IP address info replaces with zeroes (for anonymity):
$ ssh router "show route protocol bgp terse" > router.bgp # Juniper
$ flowdumper \
-B router.bgp \
-e '$src_as = $src_origin_as,
$dst_as = $dst_origin_as,
(($exporter = 0),
($srcaddr = 0),
($src_mask = 0),
($dstaddr = 0),
($dst_mask = 0),
($nexthop = 0), 1)' \
-R \
-o /tmp/%s.cflow_enc \
flows*
-B option, routing table entries that contain AS sets at the end of the AS
path are quietly discarded. (It's not so quiet if you also specified -V.) It was necessary to discard these, because I did not consider AS sets
when designing the API and therefore have no way to communicate more than
one origin AS value per for a single source or destination IP address.
There are perhaps some pathological combinations of options that currently do not produce usage error messages, but should.
Since the expression syntax is that of perl itself, there are lots of useless expressions that will happily be accepted without complaint. This is particular troublesome when trying to track down typos, for instance, with the flow variable names.
This script probably has the same bugs as the Cflow module, since it's based upon it.
Copyright (C) 1998-2002 Dave Plonka. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
perl(1), Socket, Net::Netmask, Net::Patricia, Cflow.