5 Replies Latest reply on May 24, 2016 9:32 AM by snailkhan

    NetFlow Probe/Agent for Linux - SoftFlowD is an alternative to NProbe



      I was looking for an alternative to NProbe as a NetFlow Probe/Agent for a CentOS as NProbe is not free and i wanted somehing that i could run as a Probe only and in deamon mode.  After looking at various options, I settled on SoftFlowD as an alternative and thought that I would share with the community how exactly I did it.  It works like a dream for me so enjoy!!!


      Installing SoftFlowD as a TCP Flow Based Probe

      The following is a description of how we can install a TCP Flow based probe to capture the data going in and out of a Centos Linux server and to export this in NetFlow Version 5 format to a collector for further analysis.


      First of ak, we need to ensure that we have a few utilities installed on the server to satisfy the dependencies.

      [root@wbcphpxy01 ~]# yum install libtool automake autoconf python-devel



      Once these are installed, then let’s get a copy of the softflowd compressed source files:-


      [root@wbcphpxy01 ~]# cd /root

      [root@wbcphpxy01 ~]#wget http://softflowd.googlecode.com/files/softflowd-0.9.9.tar.gz

      --2013-09-30 11:17:13--  http://softflowd.googlecode.com/files/softflowd-0.9.9.tar.gz

      Resolving softflowd.googlecode.com..., 2a00:1450:4001:c02::52

      Connecting to softflowd.googlecode.com||:80... connected.

      HTTP request sent, awaiting response... 200 OK

      Length: 91939 (90K) [application/x-gzip]

      Saving to: âsoftflowd-0.9.9.tar.gzâ


      100%[======================================>] 91,939      --.-K/s   in 0.1s


      2013-09-30 11:17:13 (673 KB/s) - âsoftflowd-0.9.9.tar.gzâ


      Now let’s decompress them:-


      [root@wbcphpxy01 ~]# tar -zxvf softflowd-0.9.9.tar.gz









































      Now that we have uncompressed the files, let’s change to the relevant directory and then run the configuration script that checks whether you have the relevant programs dependencies such as gcc in place and where those binaries are on your system:-


      [root@wbcphpxy01 ~]# cd softflowd-0.9.9


      [root@wbcphpxy01 softflowd-0.9.9]# ./configure

      checking for gcc... gcc

      checking whether the C compiler works... yes

      checking for C compiler default output file name... a.out

      checking for suffix of executables...

      checking whether we are cross compiling... no

      checking for suffix of object files... o

      checking whether we are using the GNU C compiler... yes

      checking whether gcc accepts -g... yes

      checking for gcc option to accept ISO C89... none needed

      checking for a BSD-compatible install... /usr/bin/install -c

      checking how to run the C preprocessor... gcc -E

      checking for grep that handles long lines and -e... /bin/grep

      checking for egrep... /bin/grep -E

      checking for ANSI C header files... yes

      checking for sys/types.h... yes

      checking for sys/stat.h... yes

      checking for stdlib.h... yes

      checking for string.h... yes

      checking for memory.h... yes

      checking for strings.h... yes

      checking for inttypes.h... yes

      checking for stdint.h... yes

      checking for unistd.h... yes

      checking net/bpf.h usability... no

      checking net/bpf.h presence... no

      checking for net/bpf.h... no

      checking pcap.h usability... yes

      checking pcap.h presence... yes

      checking for pcap.h... yes

      checking pcap-bpf.h usability... yes

      checking pcap-bpf.h presence... yes

      checking for pcap-bpf.h... yes

      checking for struct sockaddr.sa_len... no

      checking for struct ip6_ext.ip6e_nxt... yes

      checking for library containing daemon... none required

      checking for library containing gethostbyname... none required

      checking for library containing socket... none required

      checking for pcap_open_live in -lpcap... yes

      checking for closefrom... no

      checking for daemon... yes

      checking for setresuid... yes

      checking for setreuid... yes

      checking for setresgid... yes

      checking for setgid... yes

      checking for strlcpy... no

      checking for strlcat... no

      checking for u_int64_t... yes

      checking for int64_t... yes

      checking for uint64_t... yes

      checking for u_int32_t... yes

      checking for int32_t... yes

      checking for uint32_t... yes

      checking for u_int16_t... yes

      checking for int16_t... yes

      checking for uint16_t... yes

      checking for u_int8_t... yes

      checking for int8_t... yes

      checking for uint8_t... yes

      checking size of char... 1

      checking size of short int... 2

      checking size of int... 4

      checking size of long int... 4

      checking size of long long int... 8

      configure: creating ./config.status

      1. config.status: creating Makefile
      2. config.status: WARNING:  'Makefile.in' seems to ignore the --datarootdir setting
      3. config.status: creating config.h


      Now we need to run the make utility to build a binary executable ready to install, which is customised to your environment:-


      [root@wbcphpxy01 softflowd-0.9.9]# make

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o softflowd.o softflowd.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o log.o log.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o netflow1.o netflow1.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o netflow5.o netflow5.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o netflow9.o netflow9.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o freelist.o freelist.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o convtime.o convtime.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o strlcpy.o strlcpy.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o strlcat.o strlcat.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o closefrom.o closefrom.c

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o daemon.o daemon.c

      gcc  -o softflowd softflowd.o log.o netflow1.o netflow5.o netflow9.o freelist.o convtime.o strlcpy.o strlcat.o closefrom.o daemon.o -lpcap

      gcc -g -O2 -DFLOW_SPLAY          -DEXPIRY_RB             -I.   -c -o softflowctl.o softflowctl.c

      gcc  -o softflowctl softflowctl.o convtime.o strlcpy.o strlcat.o closefrom.o daemon.o -lpcap


      Now that we have a binary ready for installing, we just need to install the application on your system:-


      [root@wbcphpxy01 softflowd-0.9.9]# make install

      [ -d /usr/local/sbin ] || \./mkinstalldirs /usr/local/sbin

      [ -d /usr/local/share/man/man8 ] || \./mkinstalldirs /usr/local/share/man/man8

      /usr/bin/install -c -m 0755 -s softflowd /usr/local/sbin/softflowd

      /usr/bin/install -c -m 0755 -s softflowctl /usr/local/sbin/softflowctl

      /usr/bin/install -c -m 0644 softflowd.8 /usr/local/share/man/man8/softflowd.8

      /usr/bin/install -c -m 0644 softflowctl.8 /usr/local/share/man/man8/softflowctl.8

      [root@wbcphpxy01 softflowd-0.9.9]#


      Now that we have a working copy of softflowd on the system, we can review the help file for the application by typing the following:-


      [root@wbcphpxy01 ~]# softflowd -h

      -i or -r option not specified.

      Usage: softflowd [options] [bpf_program]

      This is softflowd version 0.9.9. Valid commandline options:

        -i [idx:]interface Specify interface to listen on

        -r pcap_file       Specify packet capture file to read

        -t timeout=time    Specify named timeout

        -m max_flows       Specify maximum number of flows to track (default 8192)

        -n host:port       Send Cisco NetFlow(tm)-compatible packets to host:port

        -p pidfile         Record pid in specified file

                           (default: /var/run/softflowd.pid)

        -c pidfile         Location of control socket

                           (default: /var/run/softflowd.ctl)

        -v 1|5|9           NetFlow export packet version

        -L hoplimit        Set TTL/hoplimit for export datagrams

        -T full|proto|ip   Set flow tracking level (default: full)

        -6                 Track IPv6 flows, regardless of whether selected

                           NetFlow export protocol supports it

        -d                 Don't daemonise (run in foreground)

        -D                 Debug mode: foreground + verbosity + track v6 flows

        -s sampling_rate   Specify periodical sampling rate (denominator)

        -h                 Display this help


      Now, we should be able to run the software in Debug mode in the foreground using the following command to ensure that we see the relevant messages (especially error messages):-


      [root@wbcphpxy01 ~]# softflowd -D -v 5 -i eth0 -n -T full

      Using eth0 (idx: 0)

      softflowd v0.9.9 starting data collection

      Exporting flows to []:iop

      ADD FLOW seq:1 []:1335 <> []:22 proto:6

      ADD FLOW seq:2 []:58374 <> []:1900 proto:17

      ADD FLOW seq:3 []:0 <> []:0 proto:2

      ADD FLOW seq:4 []:0 <> []:0 proto:2



      In the above example, the following explains each of the switches I have used:-


      -D                                           Debug mode, which bring this to the foreground

      -v 5                                         Version 5 of Netflow

      -i eth0                                   The Interface number

      -n         The target host IP address and port number of the collector/analyser

      -T full                                     All protocols


      Now running this is Debug mode is useful if you want to make sure that is working but it more useful to have this running in the background so the way we do that is to remove the –D statement in the option like such and you will just see the command prompt come back:-


      [root@wbcphpxy01 ~]# softflowd -v 5 -i eth0 -n -T full

      [root@wbcphpxy01 ~]#


      You can still see that the flows are being “recorded” and that they are being exported in NetFlow version 5 and set to in this case using destination port 2055.  This is done using a utility such as TCPDUMP:-


      [root@wbcphpxy01 ~]# tcpdump -n –v dst port 2055

      listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes

      14:14:01.426775 IP > UDP, length 312

      14:15:01.185508 IP > UDP, length 408

      14:16:01.944233 IP > UDP, length 168


      Now all this is fine, but it really only becomes useful if we can stop/start and restart the application like a service and have this enabled after the server has had a reboot.  To do this we edit a file called /etc/init.d/softflowd and empty the following contents into the file and save it:-


      #! /bin/bash


      # chkconfig: 2345 80 30

      # description: SoftFlow Deamon Service


      # Provides: SOFTFLOWD

      # Short-Description: Start/Stop/Restart SOFTFLOWD TCP Flow Probe

      ### END INIT INFO


      # SOFTFLOWD This init.d script is used to start SOFTFLOWD.








      OPTIONS="-v ${VERSION} -i ${INTERFACE} -n ${COLLECTOR}:${CPORT} -T full -p ${PID_FILE}"


      start_SOFTFLOWD() {

      ${SOFTFLOWD} ${OPTIONS} > /dev/null &

      return 1



      stop_SOFTFLOWD() {

      if [ -f ${PID_FILE} ]; then

      kill `cat ${PID_FILE}` 2>1 /dev/null

      \rm ${PID_FILE}





      case "$1" in



      echo -n "Starting SOFTFLOWD"


      echo " Done."




      echo -n "Stopping SOFTFLOWD"


      echo " Done."




      echo -n "Restarting SOFTFLOWD"


      sleep 1


      echo " Done."





      echo "Usage: /etc/init.d/SOFTFLOWD {start|stop|restart}"

      exit 1


      exit 0


      After saving the file, we need to change the file permissions to:-


      [root@wbcphpxy01 ~]# chmod 755 /etc/init.d/softflowd


      Now let’s make the script a loadable initialisation script as part of the “service <application name> start” function by adding this with the chkconfig command:-


      [root@wbcphpxy01 ~]# chkconfig --add softflowd


      If you need to remove the script from being initiated at boot up as a service, then issue the following:-


      [root@wbcphpxy01 ~]# chkconfig --remove softflowd


      Finally, let’s start the service:-


      [root@wbcphpxy01 ~]# service softflowd start

      Start SOFTFLOWD Done.