Agenda: exercises-netflow.txt

Network Monitoring and Management

Configure Your Router to Export Flows
-------------------------------------

1. Export flows from a router

This is a sample for doing this from the Group 1 router, rtr1.ws.nsrc.org to
the PC named pc1.ws.nsrc.org or 10.10.1.1. In each of your groups for router 1 
through router 6 you should choose one person to type in the commands to set up
router for Netflow and one PC where the Netflow exports will go.

Our router is rtr1, or 10.10.1.254 (Group 1 gateway)

Log in on the router:

   # telnet 10.10.1.254
   rtr1.ws.nsrc.org> enable

Enter the enable password

   rtr1.ws.nsrc.org# configure terminal
   rtr1.ws.nsrc.org(config)# interface FastEthernet 0/0
   rtr1.ws.nsrc.org(config)# ip route-cache flow
   rtr1.ws.nsrc.org(config)# exit

Repeat for FastExthernet 0/1 (and all interfaces you may have that
are configured)

   rtr1.ws.nsrc.org# configure terminal
   rtr1.ws.nsrc.org(config)# interface FastEthernet 0/1
   rtr1.ws.nsrc.org(config)# ip route-cache flow
   rtr1.ws.nsrc.org(config)# exit   

   rtr1.ws.nsrc.org#conf t
   rtr1.ws.nsrc.org(config)# ip flow-export destination 10.10.1.1 9996
   rtr1.ws.nsrc.org(config)# ip flow-export version 5
   rtr1.ws.nsrc.org(config)# ip flow-cache timeout active 5

This breaks up long-lived flows into 5-minute fragments. You can 
choose any number of minutes between 1 and 60. If you leave it at 
the default of 30 minutes your traffic reports will have spikes.

   rtr1.ws.nsrc.org(config)# snmp-server ifindex persist

This enables ifIndex persistence globally. This ensures that the 
ifIndex values are persisted during router reboots.

Now configure how you want the ip flow top-talkers to work:

   rtr1.ws.nsrc.org(config)#ip flow-top-talkers
   rtr1.ws.nsrc.org(config-flow-top-talkers)#top 20
   rtr1.ws.nsrc.org(config-flow-top-talkers)#sort-by bytes
   rtr1.ws.nsrc.org(config-flow-top-talkers)#end
  
Now we'll verify what we've done.

   rtr1.ws.nsrc.org# show ip flow export
   rtr1.ws.nsrc.org# show ip cache flow

See your "top talkers" across your router interfaces

   rtr1.ws.nsrc.org# show ip flow top-talkers

If it all looks good then write your running-config to non-volatile
RAM (i.e. the startup-config):

   rtr1.ws.nsrc.org#wr mem
   
You can exit from the router now:

   rtr1.ws.nsrc.org#exit
   
and on the machine where flows are being exported to you can verify that they
are arriving by doing (as root):

        # tcpdump -v udp port 9996

In addition (_PLEASE NOTE_) we are re-exporting NetFlow data from the gateway
router to all the PCs in the classroom. You can verify that these flows are
arriving by typing:

        # tcpdump -v udp port 9009
        
For the exercises we'll assume you are on a PC where flows are only arriving 
from the gateway router and we'll use the 9009 port.


Configure Your Collector
------------------------

1. Install NFdump
   NFdump is the Netflow flow collector

   We install several additional packages that we will need a bit 
   later:

Only install these if you did not already install mrtg and rrdtool:

   # apt-get install rrdtool
   # apt-get install librrds-perl
   # apt-get install librrdp-perl
   # apt-get install mrtg

If mrtg and rrdtool are already installed, then you just need these:
  
   # apt-get install librrd-dev
   # apt-get install nfdump

Or, on a single line:

   # apt-get install rrdtool mrtg librrds-perl librrdp-perl librrd-dev nfdump

   This will install, among other things, nfcapd, nfdump, nfreplay, 
   nfexpire, nftest, nfgen


2. Installing and Setting up NfSen (logged in as root)

   # cd /usr/local/src 
   # wget http://noc.ws.nsrc.org/software/nfsen-1.3.5.tar.gz
   # tar xvzf nfsen-1.3.5.tar.gz
   # cd nfsen-1.3.5
   # cd etc
   # cp nfsen-dist.conf nfsen.conf
   # joe nfsen.conf

Set the $BASEDIR variable

   $BASEDIR="/var/nfsen";

Set the users appropriately so that Apache can access files:

   $WWWUSER = 'www-data';
   $WWWGROUP = 'www-data'   

Adjust the tools path to where items actually reside:

# nfdump tools path
$PREFIX = '/usr/bin';

Set the buffer size to something small, so that we see data quickly

# Receive buffer size for nfcapd - see man page nfcapd(1)
$BUFFLEN = 2000;

Find the %sources definition, and change it to:

   %sources=(
   'rtrX'=>{'port'=>'9009','col'=>'#0000ff','type'=>'netflow'},
   );                              

Now save and exit from the file.


3. Create the netflow user on the system

   # useradd -d /var/netflow -G www-data -m -s /bin/false netflow


4. Initiate NfSen. Any time you make changes to nfsen.conf you will 
   have to do this step again.

Make sure we are in the right location:

   # cd /usr/local/src/nfsen-1.3.5

Now, finally, we install:

   # perl install.pl etc/nfsen.conf

Start NfSen

cd /var/nfsen/bin
./nfsen start


5. View flows via the web:

   # apt-get install php5
   
You can find the nfsen output here:

   http://pcN.ws.nsrc.org/nfsen/nfsen.php

(Below is only if there are problems)

Note that in /usr/local/etc/nfsen-1.3/etc/nfsen.conf there is a variable
$HTMLDIR that you may need to configure. By default it is set like this:

   $HTMLDIR="/var/www/nfsen/";

In some cases you may need to either move the nfsen directory in your web 
structure, or update the $HTMLDIR variable for your installation.

If you move items, then do:

   # /etc/init.d/apache2 restart


6. Verify that flows are arriving

Assuming that you are exporting flows from a router, or routers, to 
your collector box on port 9009 you can check for arriving data using
tcpdump:

   # tcpdump -v udp port 9009


7. Extend your Netflow configuration (Sample Only - We won't do this)

Go back to where you extracted your nfsen distribution.

   # cd /usr/local/src/nfsen-1.3.5
   # vi etc/nfsen.conf

Update your sources for new items that you migh have.
(Sample only!)

        %sources = (
        'rtr' => {'port' => '9000', 'col' => 'e4e4e4' },
        'rtr2' => { 'port' => '9001', 'col' => '#0000ff' },
        'rtr3' => { 'port' => '9002','col' => '#00cc00' },
        'rtr4' => { 'port' => '9003','col' => '#000000' },
        'rtr5' => { 'port' => '9004','col' => '#ff0000' },
        'rtr6' => { 'port' => '9005','col' => '#ffff00' },
        );

Save and exit from the nfsend.conf file.

Remember, you've updated nfsen.conf so you must re-run the install
script:

   # perl install.pl etc/nfsen.conf

Now start and stop nfsen:

   # /var/nfsen/bin/nfsen stop
   # /var/nfsen/bin/nfsen start

You can add the nfsen startup script to /etc/init.d/rc.local 
or somewhere similar to start it at bootup.)


8. Installing the PortTracker plugin (Optional or as reference)

- Go the PortTracker directory in the nfsen source distribution:

   # cd /usr/local/src/nfsen-1.3.5/contrib/PortTracker

   # joe do_compile

      # path of nfdump sources
      NFDUMP="/home/sysadmin/nfdump-1.6.2"

      # path of rrd include file rrd.h
      RRDINCLUDE=/usr/include

      # path of rrd library 
      LIBRRD=/usr/lib


- Compile nftrack:

   # ./do_compile

...

   # cp nftrack /usr/local/bin/

- Make a directory for the nftrack data

   # mkdir -p /var/log/netflow/porttracker

- Set the nftrack data directory in the PortTracker.pm module:

   # joe PortTracker.pm

    ...

       my $PORTSDBDIR = "/var/log/netflow/porttracker";

    ...

- Install the plugins into the NFSen distribution

   # cp PortTracker.pm /var/nfsen/plugins/
   # cp PortTracker.php /var/www/nfsen/plugins/

- Add the plugin definition to the nfsen.conf configuration

   # cd ~/nfsen-1.3.5
   # vi etc/nfsen.conf

    ...

       @plugins = (
           [ 'live',   'PortTracker'],
       ); 

    ...

- Re-run the installation (answer questions)

   # perl install.pl etc/nfsen.conf

- Initialize portracker database files

   # sudo -u www-data nftrack -I -d /var/log/netflow/porttracker

    (This can take a LONG time! - 8 GB worth of files will be created)

- Set the permissions so the netflow user running nfsen, and the www-data
  user running the Web interface, can access the porttracker data:

   # chown -R netflow:www-data /var/log/netflow/porttracker
   # chmod -R 775 /var/log/netflow/porttracker

- Reload:

   # /var/nfsen/bin/nfsen reload

- Check for success:

   # grep -i 'porttracker.*success' /var/log/syslog
Nov 27 02:46:13 noc nfsen[17312]: Loading plugin 'PortTracker': Success
Nov 27 02:46:13 noc nfsen[17312]: Initializing plugin 'PortTracker': Success

- Wait some minutes, and go the the nfsen GUI

    http://pcN.ws.nsrc.org/nfsen/nfsen.php

... and select the Plugins tab.