How to use a Raspberry PI 4 as a Network Sensor with Zeek and Rita

  • vnull
  • Pub Feb 19, 2021
  • Edited Jan 8, 2023
  • 10 minutes read

How to use a Raspberry PI 4 as a Network Sensor with Zeek and Rita

The original idea can be found at the following:

Modification to this setup can be found on my git repo: rita-zeek-rpi4

Ideas based on How to use a Raspberry PI as a Network Sensor

Inspired by Bill Stearns How to use a Raspberry PI as a Network Sensor intial thoughts was that RITA will not run on RPi Rasbian OS as it appears to need MongoDB 64bit. Going to attempt to try to run Ubuntu 18.04 LTS RPi 4 Modle B 4GB.


  1. Run in headless mode
  2. No GUI assuming will save on resources

Ubuntu Setup


Folow these steps: Install Ubuntu Server 20.04 LTS on Raspberry Pi 4 in Headless Mode and SSH Into It or these Install Ubuntu on Raspberry Pi

Download 18.04 server image ubuntu-18.04.5-preinstalled-server-arm64+raspi4.img.xz to substitute the others mentioned in the articales


sudo apt update && sudo apt upgrade -y


E: Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?


  1. Stop the automatic updater.

sudo dpkg-reconfigure -plow unattended-upgrades At the first prompt, choose not to download and install updates. reboot

  1. Make sure any packages in an unclean state are installed correctly.

sudo dpkg --configure -a

  1. Get your system up-top-date.

sudo apt update && sudo apt -f install && sudo apt full-upgrade

  1. Turn the automatic updater back on or not.

sudo dpkg-reconfigure -plow unattended-upgrades Select the package unattended-upgrades again.


$ sudo fuser -v /var/lib/dpkg/lock-frontend
                     USER        PID ACCESS COMMAND
                     root       2112 F.... unattended-upgr

$ ps aux | grep 2112
root      2112 66.5  8.1 366108 113508 ?       Sl   13:03   0:28 /usr/bin/python3 /usr/bin/unattended-upgrade --download-only

$ dpkg -S /usr/bin/unattended-upgrade
unattended-upgrades: /usr/bin/unattended-upgrade
sudo kill -KILL 2112 
sudo apt install -f
sudo dpkg --configure -a
sudo apt-purge unattended-upgrades


sudo hostnamectl set-hostname urhostname

sudo reboot now

Referance: Ubuntu 18.04: Disable Netplan switch back to networking /etc/network/interfaces

Configure a network interface into promiscuous mode

Note: On 18.04, we install networkd-dispatcher (see which will allow you to run any further command you might need to finish the configuration of services / interfaces. That should allow you to make sure ‘ip link set ens192 promisc on’ will persist across a reboot.

Setup & Install ifupdown


Install the ifupdown package and resolvconf

sudo apt-get update
sudo apt-get install -y ifupdown resolvconf

Setup ifupdown

Replace configuration files Delete all of the Netplan configuration files:

sudo rm -rf /etc/netplan/*.yml or back it up until up and running cp /etc/netplan/50-cloud-init.yaml /etc/netplan/50-cloud-init.yaml.bak

Open the file /etc/network/interfaces and copy and paste the following:

# The loopback network interface
auto lo
iface lo inet loopback

# Mirror
auto eth0
iface eth0 inet manual
  up ifconfig up
  up ip link set eth0 promisc on
  down ip link set eth0 promisc off
  down ip link set eth0 down

# Mgmt
allow-hotplug eth1
auto eth1
iface eth1 inet static

source /etc/network/interfaces.d/*.cfg

Setup resolv.conf

Find out whether /etc/resolv.conf is a static file or symlink by the following command:

$ ls -l /etc/resolv.conf

 /etc/resolv.conf -> ../run/resolvconf/stub-resolv.conf

Need to remove the symlink between /etc/resolv.conf and stub-resolv.conf

Issue the following command to change the symlink /etc/resolv.conf to point default dns server instead of

sudo ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf

ls -l /etc/resolv.conf



Promiscuous Mode

Enable promiscuous mode:

sudo ifconfig eth0 promisc

Validate mode insabled:

ip -d link show eth0 
2: eth0: mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
link/ether 14:fe:b5:d5:51:9e brd ff:ff:ff:ff:ff:ff promiscuity 1 addrgenmode eui64 numtxqueues 8 numrxqueues 8 gso_max_size 65536 gso_max_segs 65535

promiscuity 1 means that the interface is in promiscuous mode promiscuity 0 means that the interface is not in promiscuous mode

netstat -i
Kernel Interface table
eth0       1500 0     26631      0      0 0         27143      0      0      0 BMPR

Disable promiscuous mode

sudo ifconfig eth0 -promisc
sudo tail -f /var/log/syslog
kernel: [ 2155.176013] device eth0 left promiscuous mode

netstat -i
Kernel Interface table
eth0       1500 0     29172      0      0 0         29850      0      0      0 BMRU

Enable /etc/rc.local on Systemd

sudo systemctl status rc-local

Enable /etc/rc.local

Note: Starting with 16.10, Ubuntu doesn’t ship with /etc/rc.local file anymore. You can create the file by executing this command.

You may get this output:

● rc-local.service - /etc/rc.local Compatibility
 Loaded: loaded (/lib/systemd/system/rc-local.service; static; vendor preset: enabled)
 Active: failed (Result: exit-code) since Thu 2015-11-26 23:54:58 CST; 59s ago
 Process: 1001 ExecStart=/etc/rc.local start (code=exited, status=1/FAILURE)

Output my very, but might not get anything.


create a file:

sudo vim /etc/systemd/system/rc-local.service

Add content to it.

 Description=/etc/rc.local Compatibility

 ExecStart=/etc/rc.local start


Run the following command to make sure /etc/rc.local file is executable.

sudo chmod +x /etc/rc.local

Might need to create /etc/rc.local create the file by executing this command.

printf '%s\n' '#!/bin/bash' 'exit 0' | sudo tee -a /etc/rc.local

Execute permission to /etc/rc.local file.

sudo chmod +x /etc/rc.local

Enable the service on system boot:

sudo systemctl enable rc-local


Created symlink from /etc/systemd/system/ to /etc/systemd/system/rc-local.service.

start the service and check its status:

sudo systemctl start rc-local.service
sudo systemctl status rc-local.service


● rc-local.service - /etc/rc.local Compatibility
 Loaded: loaded (/etc/systemd/system/rc-local.service; enabled; vendor preset: enabled)
 Active: active (running) since Fri 2015-11-27 00:32:56 CST; 14min ago
 Process: 879 ExecStart=/etc/rc.local start (code=exited, status=0/SUCCESS)
 Main PID: 880 (watch)
 CGroup: /system.slice/rc-local.service

Final output:


#ethtool command to reduce processing at eth0
ethtool -K eth0 gro off rx off tx off gso off
mkdir -p /opt/bro/pcaps

screen -S capture -t capture -d -m bash -c "nice -n 15 tcpdump -i eth0 -G 3600 -w '/opt/bro/pcaps/'`hostname -s`'.%Y%m%d%H%M%S.pcap' -z bzip2 '(tcp[13] & 0x17 != 0x10) or not tcp'"

ip link set eth0 promisc on
/usr/local/zeek/bin/zeekctl start

exit 0

Note: ethtool has a fixed parameter for large-receive-offload, so needed to edit this in the rc.local

fixed parameter like large-receive-offload:

sudo ethtool -K eth0 lro on
Cannot change large-receive-offload
Could not change any device features
ethtool -k eth0 | grep large-receive-offload
large-receive-offload: off [fixed]

Referance: How to Enable /etc/rc.local with Systemd

Zeek IDS Installation on Raspberry PI

Downloading and installing pre-requisites to Zeek from source

sudo apt-get install cmake make gcc g++ flex bison libpcap-dev libssl-dev python-dev swig zlib1g-dev

Addtional Packages

sudo apt-get install libmaxminddb-dev postfix curl git

Download and Install Zeek From git Source

git clone --recursive
cd zeek

If everything goes right and no issues

sudo make install

Set the PATH

export PATH=/usr/local/zeek/bin:$PATH
vim ~/.profile
export PATH=/usr/local/zeek/bin:$PATH

Setting up Zeek

All the Zeek files should be installed in /usr/local/zeek

Edit /usr/local/zeek/etc/node.cfg to set the interface to monitor; usually interface eth0


Edit /usr/local/zeek/networks.cfg to add the IP addresses and short descriptions of your different routed networks. For example: Private IP space Private IP space Private IP space
Edit /usr/local/zeek/etc/zeekctl.cfg and set the

Edit /usr/local/zeek/etc/zeekctl.cfg and set the

MailTo =

Replace to your email address to receive reports from your Zeek instance and set the LogRotationInterval to the log archiving frequency.

Starting up Zeek

Start the Zeek control shell with


On the first time use – we need to do the initial installation

[ZeekControl] > install Then to start the zeek process

[ZeekControl] > start I also like using

[ZeekControl] > deploy to refresh settings when starting

To stop the Zeek process

[ZeekControl] > stop Other commands in zeekctl are available with the ? notation

Also check

/usr/local/zeek/logs/current for the latest log files and

/var/log/mail.log to troubleshoot Zeek e-mail reports to your e-mail address.

Add the following to /etc/rc.local file before the exit 0 line. IDS functionality is better with promiscuous mode on for the network interface. This will forward all packets to the CPU and not just the ones destined for the host.

ip link set eth0 promisc on
/usr/local/zeek/bin/zeekctl start

exit 0

Zeek needs to occasionally perform some scheduled maintenance:

crontab -e 
(select an editor and enter the following line)
 */5 * * * * /usr/local/zeek/bin/zeekctl

Changing the log file format for better ingestion

The best way for external software to ingest your zeek logs is to convert them to JSON format. In the original config, Zeek creates human readable text tables for each kind of log file created in /usr/local/zeek/logs/current such as:

 cat capture_loss.log
#separator \x09
#set_separator  ,
#empty_field    (empty)
#unset_field    -
#path   capture_loss
#open   2019-08-31-02-04-06
#fields ts      ts_delta        peer    gaps    acks    percent_lost
#types  time    interval        string  count   count   double
1567213446.308621       900.000053      zeek    0       0       0.0

Edit /usr/local/zeek/share/zeek/site/local.zeek;

Add the following to the end of the file;

#JSON Output
@load policy/tuning/json-logs.zeek

Save and close the site file; From the command-line restart zeek as the configuration has changed. zeekctl deploy Check to make sure your logs are now in JSON format.

 cat /usr/local/zeek/logs/current/packet_filter.log
{"ts":1567213927.478291,"node":"zeek","filter":"ip or not ip","init":true,"success":true}

Referance: Zeek IDS Installation on Raspberry PI Part 1

Installing MongoDB to the Raspberry Pi

1. Upgrade all existing packages by running the command below.

sudo apt update
sudo apt upgrade

2. Install the MongoDB server from the Raspbian repository

sudo apt install mongodb

3. Start the MongoDB service.

sudo systemctl enable mongodb
sudo systemctl start mongodb

Might get error about unable to resolve host (none)”

/etc/hosts has an entry for localhost. It should have something like:    localhost.localdomain localhost    my-machine

4. Run the following command to interact with the database by using the command line.


Checking the Mongo Service and Database

1. Check the status of our MongoDB server.

sudo systemctl status mongodb

Response as we have shown below.

● mongodb.service - An object/document-oriented database
   Loaded: loaded (/lib/systemd/system/mongodb.service; enabled; vendor
   Active: active (running) since Thu 2021-02-18 01:22:45 UTC; 1h 34min
     Docs: man:mongod(1)
 Main PID: 2066 (mongod)
    Tasks: 23 (limit: 4443)
   CGroup: /system.slice/mongodb.service
           └─2066 /usr/bin/mongod --unixSocketPrefix=/run/mongodb --con

2. Check the status of Mongo itself by retrieving its connection status.

mongo --eval 'db.runCommand({ connectionStatus: 1 })'

MongoDB shell version v3.6.3
connecting to: mongodb://
MongoDB server version: 3.6.3
        "authInfo" : {
                "authenticatedUsers" : [ ],
                "authenticatedUserRoles" : [ ]
        "ok" : 1

Referance: Installing MongoDB to the Raspberry Pi

install Golang (Go) on Raspberry Pi

Current stable version available at Golang official website is v1.16 and there is a distribution packaged for ARMv8 CPU go1.16.linux-arm64.tar.gz


sudo tar -C /usr/local -xzf o1.16.linux-arm64.tar.g
rm go1.12.6.linux-armv6l.tar.gz

Set PATH environment variable Golang is installed. To do that, edit the ~/.profile file:

Scroll all the way down to the end of the file and add the following:

vim ~/.profile


Re-load profile

source ~/.profile

which go to find out where the Golang installed and go version to see the installed version and platform.

which go
go version
go version go1.12.6 linux/arm

Referance: install Golang (Go) on Raspberry Pi

Building RITA

Aa root build RITA from source code see addtional setps here or summary below.

  1. git clone
  2. cd rita
  3. make
  4. make install to install the binary to /usr/local/bin/rita

Configuring the system

RITA requires some directories to be created for it to function correctly.

sudo mkdir /etc/rita && sudo chmod 755 /etc/rita sudo mkdir -p /var/lib/rita/logs && sudo chmod -R 755 /var/lib/rita

Copy config file RITA source code dir.

sudo cp etc/rita.yaml /etc/rita/config.yaml && sudo chmod 666 /etc/rita/config.yaml

**Test ** using the rita test-config

  UpdateCheckFrequency: 14
  ConnectionString: mongodb://localhost:27017
  AuthenticationMechanism: ""
  SocketTimeout: 2h0m0s
    Enable: false
    VerifyCertificate: false
    CAFile: ""
  MetaDB: MetaDatabase
  DefaultChunks: 24
  rolling: false
  currentchunk: 0


Great way to monitor local area network with network tap on the cheap!!!

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