Moloch is an open source, large scale, full packet capturing, indexing, and database system.
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Current Moloch users, please fill out the Moloch User Survey.

What is Moloch?

Moloch is an open source, large scale, full packet capturing, indexing, and database system. Moloch augments your current security infrastructure to store and index network traffic in standard PCAP format, providing fast, indexed access. An intuitive and simple web interface is provided for PCAP browsing, searching, and exporting. Moloch exposes APIs which allow for PCAP data and JSON formatted session data to be downloaded and consumed directly. Moloch stores and exports all packets in standard PCAP format allow you to also use your favorite PCAP ingesting tools, such as wireshark, during your analysis workflow.

Access to Moloch is protected by using HTTPS with digest passwords or by using an authentication providing web server proxy. All PCAPs are stored on the sensors and are only accessed using the Moloch interface or API. Moloch is not meant to replace an IDS but instead work along side them to store and index all the network traffic in standard PCAP format, providing fast access. Moloch is built to be deployed across many systems and can scale to handle tens of gigabits/sec of traffic. PCAP retention is based on available sensor disk space. Meta data retention is based on the Elasticsearch cluster scale. Both can be increased at anytime and are under your complete control.

Sessions Tab

Sample sessions screen shot

SPI View Tab

Sample spiview screen shot

RPM & DEB Downloads

Starting with Moloch 0.15 we are now offering prebuilt RPMs and DEBs. These are still experimental. Please open a github issue with any feedback or bugs found.

Quick Start

If the prebuilt packages are not working, easybutton makes it possible to build a demo host quickly. Run ./ in the Moloch source distribution to build a complete single-machine Moloch system. This is good for a demo and can also be used as a starting point for a real production deployment.


The Moloch system is comprised of 3 components

  1. capture - A threaded C application that monitors network traffic, writes PCAP formatted files to disk, parses the captured packets and sends meta data (SPI data) to elasticsearch.
  2. viewer - A node.js application that runs per capture machine and handles the web interface and transfer of PCAP files.
  3. elasticsearch - The search database technology powering Moloch.

Building and Installing

Moloch is a complex system to build and install. The following are rough guidelines.

Installing Elasticsearch

Recommended version 2.4.4, Moloch versions since 0.17.0 requires at least 2.4.0. Elasticsearch 5.x is not recommended for production use yet.

  1. Prep the elasticsearch machines by increasing max file descriptors and allowing memory locking. On CentOS and others this is done by adding the following to bottom of: /etc/security/limits.conf:

    *                -      nofile          128000
    *                -      memlock         unlimited
  2. If this is a dedicated machine, disable swap by commenting out the swap lines in /etc/fstab and either reboot or use the swapoff command.

  3. Download elasticsearch. Important: At this time all development is done with elasticsearch 2.4.4.

  4. Uncompress the archive you downloaded.

  5. Install elasticsearch-head BEFORE pushing to all machines:

    cd elasticsearch-*
    bin/plugin -install mobz/elasticsearch-head
  6. Create or modify elasticsearch.yml and push it to all machines. (See db/elasticsearch.yml.sample in the Moloch source distribution for an example.)

    • set to something unique
    • set to ${ES_HOSTNAME}
    • set node.max_local_storage_nodes to number of nodes per machine
    • set index.fielddata.cache: node
    • set and path.logs
    • set gateway.type: local
    • set gateway.recover_after_nodes should match the number of nodes you will run
    • set gateway.expected_nodes to the number of nodes you will run
    • disable
    • enable and set the list of hosts
  7. Create an elasticsearch launch script or use one of the ones out there. (See db/ in the Moloch source distribution for a simple one.)

    • Make sure you call ulimit -a first
    • set ES_HEAP_SIZE=20G (or whatever number you are using, less then 32G)
    • set JAVA_OPTS="-XX:+UseCompressedOops" if using real Java
    • set ES_HOSTNAME to `hostname -s`
  8. Start the cluster, waiting ~5s between starting each node to give them time to properly mesh.

  9. Use elasticsearch-head to look at your cluster and make sure it is GREEN.

  10. Inside the installed $MOLOCH_PREFIX/db directory run the http://A_ES_HOSTNAME:9200 init script.

  11. Check elasticsearch-head again and make sure it is still GREEN and now you should see some of the indexes.

Building Capture

  1. Install prerequisite standard packages.

    • CentOS:

      yum install wget curl pcre pcre-devel pkgconfig flex bison gcc-c++ zlib-devel e2fsprogs-devel openssl-devel file-devel make gettext libuuid-devel perl-JSON bzip2-libs bzip2-devel perl-libwww-perl libpng-devel xz libffi-devel
    • Ubuntu:

      apt-get install wget curl libpcre3-dev uuid-dev libmagic-dev pkg-config g++ flex bison zlib1g-dev libffi-dev gettext libgeoip-dev make libjson-perl libbz2-dev libwww-perl libpng-dev xz-utils libffi-dev
    • OS X:

      port install yara libpcap openssl pcre flex bison zlib file gettext p5-JSON p5-libwww-perl libffi xz ossp-uuid libgeoip glib2
      ./configure --with-libpcap=/opt/local --with-yara=/opt/local --with-GeoIP=/opt/local LDFLAGS=-L/opt/local/lib --with-glib2=no GLIB2_CFLAGS="-I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include" GLIB2_LIBS="-L/opt/local/lib -lglib-2.0 -lgmodule-2.0 -lgobject-2.0 -lgio-2.0"
  2. Building capture can be a pain because of OS versions.

    • Try ./ which will download all the following, compile them statically, and run the local configure script.

    • Or if you want build yourself, or use some already installed packages then here are the pieces you need:

      • glib-2 version 2.40 or higher (2.50.2 is recommended):

        ./configure --disable-xattr --disable-shared --enable-static --disable-libelf --disable-selinux --disable-libmount --with-pcre=internal
      • yara version 1.6 or higher:

        wget -O yara-3.5.0.tar.gz
        ./configure --enable-static
      • MaxMind GeoIP - The OS version may be recent enough::

        wget libtoolize -f # Only some platforms need this ./configure --enable-static

      • libpcap - version 1.3 or higher (most OS versions are older):

        ./configure --disable-dbus
  3. Run configure. Optionally use the --with-<foo> directives to use static libraries from build directories.

  4. Run make.

Building Viewer

  1. Install Node.js version 4.6.0, currently 6.x is not supported. (Moloch versions before 0.16 required 0.10.x)
  2. In the viewer directory run npm update.


  1. Make sure you download the latest freely available GeoIP and RIR files.

  2. Edit the config.ini file.

  3. In the viewer directory, run addUser.js to add users. Pass the --admin flag if you want admin users that can edit users from the web site. This is a good test if elasticsearch and config.ini are setup correctly:

    node addUser.js <userid> "<Friendly Name>" <password> [--admin]
  4. Edit the db/ script, and set it up in the crontab on one machine.

Get it Running

If you've made it this far, you are awesome!

On each capture machine you need to run at least one moloch-capture and one moloch-viewer. You may use the good old inittab. Add this to /etc/inittab (where /home/moloch is the prefix where Moloch is installed):


Sample versions can be found in capture/ and viewer/ in the Moloch source distribution.

Test it Out

Point your browser to any Moloch instance at https://<hostname>:<port> and start tinkering!

Advanced Configuration

Hardware Requirements

Moloch is built to run across many machines for large deployments. The following are rough guidelines for capturing large amounts of data with high bit rates, obviously tailor for your specific situation. It is not recommended to run the capture and elasticsearch processes on the same machines for highly utilized GigE networks.

For demo, small network, or home installations everything on a single machine is fine.

  1. Moloch capture/viewer systems
    • One dedicated management network interface and CPU for OS
    • For each network interface being monitored recommend ~10G of memory and another dedicated CPU
    • If running suricata or another IDS add an additional two (2) CPUs per interface, and an additional 5G memory (or more depending on IDS requirements)
    • Disk space to store the PCAP files: We recommend at least 10TB, xfs (with inode64 option set in fstab), RAID 5, at least 5 spindles)
    • Disable swap by removing it from fstab
    • If networks are highly utilized and running IDS then CPU affinity is required
    • See FAQ Entry
  2. Moloch elasticsearch systems (some black magic here!)
    • 1/4 * Average_Total_Gigabit_Sec * Number_of_Days_of_History is a ROUGH guideline for number of elasticsearch instances (nodes) required. (Example: 1/4 * 8 Average Gb/s * 7 days = 14 nodes)
    • Each elasticsearch node should have ~30G-64G memory (20G-32G [no more!] for the java process, at least 10G for the OS disk cache)
    • You can have multiple nodes per machine (Example 128G machine can have 2 ES nodes, 32G for each of the java processes and 64G saved for the disk cache)
    • Disable swap by removing it from fstab
    • Obviously the more nodes, the faster responses will be
    • You can always add more nodes, but it's hard to remove nodes
    • See FAQ Entry

Example Configuration

Here is an example system setup for monitoring 8x GigE highly-utilized networks, with an average of ~5 Gigabit/sec, with ~7 days of pcap storage.

  • capture/viewer machines
    • 8x PenguinComputing Relion 4724
    • 48GB of memory
    • 40TB of disk-
    • Running Moloch and Suricata
  • elasticsearch machines
    • 10x HP DL380-G7
    • 128GB of memory
    • 6TB of disk
    • Each system running 2 nodes

Security Information

Ports Used

  • tcp 8005 - Moloch web interface
  • tcp 9200-920x (configurable upper limit) - Elasticsearch service ports
  • tcp 9300-930x (configurable upper limit) - Elasticsearch mesh connections

Important Considerations

  • Elasticsearch provides NO security, so iptables MUST be used allowing only Moloch machines to talk to the elasticsearch machines (ports 9200-920x) and for them to mesh connect (ports 9300-930x). An example with 3 ES machines 2 nodes each and a viewer only machine::
    for ip in moloches1 moloches2 moloches3 molochvieweronly1; do

    iptables -A INPUT -i eth0 -p tcp --dport 9300 -s $ip -j ACCEPT iptables -A INPUT -i eth0 -p tcp --dport 9200 -s $ip -j ACCEPT iptables -A INPUT -i eth0 -p tcp --dport 9301 -s $ip -j ACCEPT iptables -A INPUT -i eth0 -p tcp --dport 9201 -s $ip -j ACCEPT

    done iptables -A INPUT -i eth0 -p tcp --dport 9300 -j DROP iptables -A INPUT -i eth0 -p tcp --dport 9200 -j DROP iptables -A INPUT -i eth0 -p tcp --dport 9301 -j DROP iptables -A INPUT -i eth0 -p tcp --dport 9201 -j DROP

  • Moloch machines should be locked down, however they need to talk to each other (port 8005), to the elasticsearch machines (ports 9200-920x), and the web interface needs to be open (port 8005).

  • Moloch viewer should be configured to use SSL.

    • It's easiest to use a single certificate with multiple DNs.
    • Make sure you protect the cert on the filesystem with proper file permissions.
  • It is possible to set up a Moloch viewer on a machine that doesn't capture any data that gateways all requests.

    • It is also possible to place apache in front of moloch, so it can handle the authentication and pass the username on to moloch
    • This is how we deploy it
  • A shared password stored in the Moloch configuration file is used to encrypt password hashes AND for inter-Moloch communication.

    • Make sure you protect the config file on the filesystem with proper file permissions.
    • Encrypted password hashes are used so a new password hash can not be inserted into elasticsearch directly in case it hasn't been secured.


For now this README is the bulk of the documentation. This will improve over time.


For answers to frequently asked questions, please see the FAQ.


We use GitHub’s built-in wiki located at


Currently upgrading from previous versions of Moloch is a manual process, however recorded sessions and pcap files should be retained

  • Update the moloch repository from github
  • Build the moloch system using ""
  • Shut down currently running old capture and viewer processes
  • Optionally use "make install" to copy the new binaries and other items and/or push the new items to the capture hosts
  • Run "npm update" in the viewer directory if not using "make install"
  • Make sure ES is running and update the database using the "db/ host:port upgrade" script
  • Start the new capture and viewer processes