Configuring YAF with SiLK

This tutorial is a step-by-step guide for setting up YAF and SiLK on a single machine for standalone Flow collection and analysis. These instructions assume the user is on a Fedora, Redhat, or other RPM-based system.

Install the Tools

This section is a brief summary of the installation of YAF and SiLK. For detailed instructions, including using prebuilt RPMs from the SEI's Forensic Team's Linux Tool Repository, see this page.

Install the Compiler and the Prerequisites

$ yum groupinstall "Development Tools"
$ yum install libpcap libpcap-devel pcre pcre-devel glib2-devel

Build and Install the NetSA Tools

libfixbuf

Build and install libfixbuf.

$ tar -xvzf libfixbuf-3.0.0.tar.gz
$ cd libfixbuf-3.0.0
$ ./configure
$ make
$ make install

YAF

Build and install YAF. The minimum recommended options are shown here; see the installation page for other options.

Note: If you are upgrading YAF, the make install command here will overwrite your exiting /usr/local/etc/yaf.conf file. Consider making a backup of that file first.

$ tar -xvzf yaf-3.0.0.tar.gz
$ cd yaf-3.0.0
$ ./configure --enable-applabel --enable-dpi
$ make
$ make install

When building YAF from source, the following file must be installed by hand. It allows running yaf as a service:

$ cp etc/init.d/yaf /etc/init.d/
$ chmod +x /etc/init.d/yaf

SiLK

Build and install SiLK. It is best if you can specify the default location of the SiLK repository at build time, though this can be changed later via an environment variable. Here, we use /data as the SiLK repository.

$ tar -xvzf silk-3.19.2.tar.gz
$ cd silk-3.19.2
$ ./configure --with-libfixbuf=/usr/local/lib/pkgconfig \
      --enable-ipv6 --enable-data-rootdir=/data
$ make
$ make install

Setup SiLK

This example uses /data as the location of the SiLK repository:

$ mkdir -p /data

The default silk.conf that comes with the SiLK distribution is typically sufficient and should be copied to the repository:

$ cp /usr/local/share/silk/twoway-silk.conf /data/silk.conf

Note: If you have installed from an RPM, you will find the above file in the /usr/share/silk directory.

To run rwflowpack as a service:

Note: If you have installed from an RPM, these files are already in place, and you need to edit /etc/sysconfig/rwflowpack.conf below.

$ cp /usr/local/share/silk/etc/init.d/rwflowpack /etc/init.d/rwflowpack
$ chmod +x /etc/init.d/rwflowpack
$ cp /usr/local/share/silk/etc/rwflowpack.conf /usr/local/etc/rwflowpack.conf

To configure rwflowpack, edit /usr/local/etc/rwflowpack.conf:

#/usr/local/etc/rwflowpack.conf
ENABLED=1
statedirectory=/var/lib/rwflowpack
CREATE_DIRECTORIES=yes
BIN_DIR=/usr/local/sbin
SENSOR_CONFIG=/data/sensor.conf
DATA_ROOTDIR=/data
SITE_CONFIG=/data/silk.conf
PACKING_LOGIC=
INPUT_MODE=stream
INCOMING_DIR=${statedirectory}/incoming
ARCHIVE_DIR=${statedirectory}/archive
FLAT_ARCHIVE=0
ERROR_DIR=  #${statedirectory}/error
OUTPUT_MODE=local
SENDER_DIR=${statedirectory}/sender-incoming
INCREMENTAL_DIR=${statedirectory}/incremental
COMPRESSION_TYPE=
POLLING_INTERVAL=
FLUSH_TIMEOUT=
FILE_CACHE_SIZE=
FILE_LOCKING=1
PACK_INTERFACES=0
LOG_TYPE=syslog
LOG_LEVEL=info
LOG_DIR=${statedirectory}/log
PID_DIR=${LOG_DIR}
USER=root
EXTRA_OPTIONS=

The sensor.conf is required to setup the listening probe. Change the internal-ipblocks to match your network

probe S0 ipfix
   listen-on-port 18001
   protocol tcp
end probe

sensor S0
   ipfix-probes S0
   internal-ipblocks 192.168.1.0/24 10.10.10.0/24
   external-ipblocks remainder
end sensor

Move the sensor.conf to the repository:

$ mv sensor.conf /data

Start rwflowpack:

$ service rwflowpack start

Verify that rwflowpack is listening on port 18001:

$ netstat -vnatpl

To use the SiLK command line tools, you may need to set the SILK_DATA_ROOTDIR variable:

$ export SILK_DATA_ROOTDIR=/data

Configure YAF

Create a directory for the yaf log file:

$ mkdir /var/log/yaf
$ mkdir /var/log/yaf/log
$ mkdir /var/log/yaf/run

$ export LTDL_LIBRARY_PATH=/usr/local/lib/yaf

To configure yaf, edit the configuration file /usr/local/etc/yaf.conf:

Note: If you have installed from an RPM, this file is in /etc/yaf.conf.

ENABLED=1
YAF_CAP_TYPE=pcap
YAF_CAP_IF=eth0
YAF_IPFIX_PROTO=tcp
YAF_IPFIX_HOST=localhost
YAF_IPFIX_PORT=18001
YAF_STATEDIR=/var/log/yaf
YAF_EXTRAFLAGS="--silk --applabel --max-payload=2048 --dpi"

Start YAF

Either start YAF via service

$ service yaf start

or invoke yaf from the command line. See the following 2 examples.

Example yaf command line for processing a PCAP file:

$ /usr/local/bin/yaf \
    --in <PCAP FILE> \
    --ipfix tcp \
    --out localhost \
    --ipfix-port 18001 \
    --log /var/log/yaf/yaf.log \
    --verbose \
    --silk \
    --dpi --max-payload 2048

Example yaf command line for sniffing interface eth0:

$ /usr/local/bin/yaf \
    --in eth0 --live pcap \
    --ipfix tcp \
    --out localhost \
    --ipfix-port 18001 \
    --log /var/log/yaf/yaf.log \
    --verbose \
    --silk \
    --dpi --max-payload 2048

If you see an error similar to:

Starting yaf:    /usr/local/bin/yaf: error while loading shared libraries: libairframe-2.5.0.so.4: cannot open shared object file: No such file or directory [Failed]

Run:

$ ldconfig

Or add /usr/local/lib to the LD_LIBRARY_PATH environment variable.

Confirm SiLK is creating flow records:

$ rwfilter --proto=0- --type=all --pass=stdout | rwcut | head