Bro on FreeBSD Using Netmap

NETMAP is a framework for very fast packet I/O from userspace with support for FreeBSD, Linux, and even Windows. Here, we’ll show how to set Bro up to use it.

Bro provides support for monitoring interfaces using netmap. However, as of FreeBSD 11.1 (bro-2.5.1) the binary package doesn’t ship with the needed netmap plugin. Furthermore, the port doesn’t support building any auxiliary plugins. Not to worry, we’ll just install Bro from source. It’s painless, trust me. 🙂

Setup used:
– FreeBSD 11.1-RELEASE
– NIC – Intel (igb driver)

1. First, we’ll need to install the necessary dependencies for compiling bro.

pkg install -y bash git flex bison cmake libpcap python py27-sqlite3 caf swig30`

2. Download the source tarball and extract it.

mkdir /usr/local/src && cd /usr/local/src
tar xzf bro-2.5.2.tar.gz && rm bro-2.5.2.tar.gz
cd bro-2.5.2

2. Let’s compile bro. Note, if you just need the plugin (for another system with a binary install using pkg), don’t run `make install`. Instead, after performing the build, just grab `./build/dist/Bro_Netmap-0.1.tar.gz` and copy/extract it where you need (with similiar FreeBSD version). Otherwise, proceed with the typical configure, make, and make install.

./configure && make -j2 && make install

3. Now we can compile and install the netmap plugin.

cd aux/plugins/netmap
./configure && make && make install

4. Now, we just need to configure bro to use netmap. Here, we’re instructing bro to create 4 load balancer processes for monitoring the the igb1 interface.

cat >/usr/local/bro/etc/node.cfg <<EOF

If the interface you’re having Bro monitor is dedicated to Bro and nothing else, enable `promisc` on the interface. Just edit /etc/rc.conf:

ifconfig_igb3="promisc mtu 9000 up"

5. This is all well and good, however packets won’t be balanced across your four `lb_procs` without the help of a utility called `lb`. There’s currently no port for `lb` and you won’t find it with other netmap utilities shipped under `/usr/src/tools/tools/netmap`. We’ll have to compile it manually.

cd /usr/local/src
unzip && rm
cd netmap-master/apps/lb
pkg install gmake
cp lb /usr/local/bin/

Now, lets start `lb` in the background and fire up Bro.
Make sure to create the same amount of pipes (`-p`) as `lb_procs` from the Bro config.

lb -i igb1 -p 4&
/usr/local/bro/bin/broctl deploy
cd /usr/local/bro/logs/current

You should now see some logs start to roll in.

6. Okay now, let’s create some init scripts so both `lb` and `bro` start at boot time.

fetch -o /usr/local/etc/rc.d/bro
fetch -o /usr/local/etc/rc.d/lb
chmod 555 /usr/local/etc/rc.d/{lb,bro}

That’s all folks. If you have any questions or tips, you can email me at

Install Bro on pfSense

I’ve been working with Bro a lot lately and thought it’d be worth trying to get Bro running on pfSense. In an ideal situation, you wouldn’t normally run an IDS on your firewall, but for low bandwidth installations or the budget constrained, it’ll work fine.

1. You’ll need to enable ssh access to your pfSense firewall as it’s not enabled by default. To do this, login to pfsense and browse to System > Advanced, then scroll down to the SSH section and check ‘Enable Secure Shell’.

I recommend setting up pub key authentication by adding your public key to the admin user in pfsense. This will allow you to login via ssh without using a password. Just don’t lose your private key!

2. Now open a terminal and ssh into pfsense. Note, we’re using the ‘root’ user instead of the normal ‘admin’ you typically use to login via web interface.

ssh root@

You’ll then be presented with a text interface. You’ll want to drop to a shell which is option ‘8’.

3. By default, pfSense disables upstream pkg repositories (for good reason). So lets re-enable them albeit, temporarily. There are two files you’ll need to edit.


Make it look like:

FreeBSD: { enabled: yes }

4. Now, we can update the pkg cache and get on with installing and configuring bro.

pkg update && pkg install -y bro

5. Bro should now be installed. **You should now reverse the changes you made in step 3.** You’ll need to pick which interface you’d like Bro to monitor. I’m going to monitor my (LAN) interface which equates to ‘igb1’ for my Intel NIC.

cat > /usr/local/etc/node.cfg <<EOF

6. Next, we’ll disable status emails, and have bro rotate logs once a day instead of the default one hour.

cat > /usr/local/etc/broctl.cfg <<EOF
MailTo = root@localhost
MailConnectionSummary = 0
MinDiskSpace = 0
MailHostUpDown = 0
LogRotationInterval = 86400
LogExpireInterval = 0
StatsLogEnable = 1
StatsLogExpireInterval = 1
StatusCmdShowAll = 0
CrashExpireInterval = 1
SitePolicyScripts = local.bro
LogDir = /usr/local/logs
SpoolDir = /usr/local/spool
CfgDir = /usr/local/etc

7. Have bro check your configuration and start it up. While the ‘deploy’ command will automatically run ‘check’ for you, it’s good practice to run it by itself after any modifications to Bro before deploying those changes.

broctl check && broctl deploy

8. You should now be able to watch the logs Bro is generating.

tail -f /usr/local/logs/current/*

So there you have it, bro running on pfSense. In upcoming articles, I’ll dive into parsing bro logs using `bro-cut` and also how to setup Bro to push logs into an Apache Kafka pipeline for more fun and profit.