CyberSecurity Ninjas 网络空间安全忍者

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Croissants 牛角面包 - Intrusion Detection and Prevention System 防御入侵系统 (Network)


This project is discontinued. Please refer to “Rosemary” or “Garland” projects when necessary.

Networks and computers that are opened to the public facing hacker attacks from all over the world every day. Once we are compromised, we would be one of the cyber crime victims. Our tasty Croissants is a high performance and ultra-low latency Intrusion Detection and Prevention System (IDPS). Unlike well known and famous brands for large business enterprises in the market, Croissants is available free of charge that everyone can afford. It is ideal for home, Small Office Home Office (SOHO) and Small Medium Business (SMB).

Not a Network Security Monitoring (NSM) or Information Security (InfoSec) expert? No problem! Our Croissants really is the “Plug, Play and Forget” system of your dreams. Don’t be the next cyber crime victims, try Croissants now!

Croissants is designed by a hacker to defend against hackers. He knows what hackers are doing and thinking, regardless of whether they are ethical or malicious.







Croissants is an Open Source Project which is released under GPLv3 License and it is developed by Samiux.

Please keep in mind that Croissants is available FREE OF CHARGE.

Croissants is designed and developed by Samiux since 2012.






1.0 Installation Guide

1.1 Download and Install

sudo -sH

cd /root

sudo apt install git net-tools

git clone

cd idps

If your monitoring network interface is a WIFI device, you need to copy /root/idps/wifi directory to /root. When your monitoring network interface is a Ethernet device, you need to copy /root/idps/lan directory to /root.

cp wifi/* /root


cp lan/* /root
cd /root/idps

cp -R rules/ /root
cp * /root

cd /root

nano nsm.conf

chmod +x nsm_install

sudo ./nsm_install

Make sure you edit nsm.conf before running nsm_install

The definition of nsm.conf is here (outdated, please refers to nsm.conf).

1.2 Post Installation (Optional)

You are required to update the rules. However, you should wait until the Suricata is starting up completely. You may wait for about 15 minutes for the start up. Or see <Notice> - rule reload complete at the end of the following command.

sudo tail -f /var/log/suricata/suricata.log

Then run :

sudo nsm_rules_update

1.3 ChangeLog

Croissants ChangeLog

2.0 User Guide

WARNING : Make sure port 19999 is not opened to the public.

2.1 Glances

Text mode monitoring tool for the performance of Croissants.


2.2 Netdata (optional)

Graphic mode monitoring tool for the performance of Croissants.

sudo sed -i 's/127\.0\.0\.1/0\.0\.0\.0/' /etc/netdata/netdata.conf
sudo systemctl restart netdata


Since netdata consumes a lot of resources, if you encounter any performance problem, you are recommended to disable it.

sudo systemctl disable netdata
sudo systemctl stop netdata

2.3 Suricata Health Check

sudo tail -f /var/log/suricata/stats.log | grep drop

Press CTRL+c to exit.

2.4 Suricata Event Log

sudo tail -f /var/log/suricata/fast.log

Press CTRL+c to exit.

2.5 Rules Management

If you want to disable some rules as they are false positive, you can edit the “disable.conf” of suricata-update.

sudo nano /etc/suricata/disable.conf

If you want to drop some traffic, you can edit the “drop.conf” of suricata-update.

sudo nano /etc/suricata/drop.conf

If you want to modify some rules, you can edit the “modify.conf” of suricata-update.

sudo nano /etc/suricata/modify.conf

After updated the configuration files, you should run the following command to make the changes effective.

sudo nsm_rules_update

2.6 Ubuntu Update

sudo update_ubuntu

2.7 Auto Configuration

Whenever you changed the nsm.conf file, you need to run the following command in order to make it effective.

sudo nano /etc/croissants/conf.d/nsm.conf

sudo /etc/croissants/conf.d/auto_config

3.0 Hall of Fame

Nathan Paquin - Unix System Expert and InfoSec guy (IRC nick : sys)
Omnish - Gamer with InfoSec in mind (IRC nick : omnish)
Alpharyon - Ultra speed internet user with InfoSec in mind

4.0 Troubleshooting

If you cannot access internet when you are behind the Croissants, Suricata may be down unexpectedly. You can check if it is running or not by the following command :

sudo ps aux | grep suricata

If it is not running, you can issue the following command to start it :

sudo systemctl restart suricata

You can check the suricata.log at /var/log/suricata/suricata.log. Please allow about 15 minutes for Suricata fully starting.

5.0 FAQ

(1) What is the function of the third network interface?

One is for incoming traffic (from modem or ISP) and the other is for outgoing traffic (to router or switch). The third one is connected to the switch for management purpose. It is also used for updating the rules and system.

(2) Which network interface is used for the installation?

The monitoring network interface is good for installation. Incoming and outgoing network interfaces may cause problem during the installation.

(3) How to check what network interfaces are in my box?

ls /sys/class/net

(4) How to deploy Croissants?

The following is the recommended connection method of Croissants. However, you can connect it behind router too.

Network Based

         (Incoming)             (Outgoing, WAN)              (LAN)           
   Modem ----------- Croissants ---------------- Router ----------------- PCs
                          |                      (WIFI)                      
                          |                        | (LAN)                   
                                                                                +------- WIFI AP
                                                                                |       (if any)
         (Incoming)             (Outgoing, WAN)           (LAN)                 |
   Modem ----------- Croissants ---------------- Router -------- Switch --------+
                          |                      (WIFI)             |           |
                          |                                         |           |
                          +-----------------------------------------+           +------- PCs

                                                                    +------- WIFI AP
         (Incoming)            (Outgoing, Port #1)                  |
5G Modem ----------- Croissants ---------------- Switch ------------+
WIFI Router (unused)      |                        |                |
                          |                        |                |
                          +------------------------+                +------- PCs

Do not use the wifi that comes with 5G modem as the traffic flow does not protected by Croissants.

(5) When will the rules are updated?


Between 0200 and 0600 hours every day, Croissants will do the housekeeping and updating. The defending work of Croissants may be interrupted during this period. Outdated logs will be deleted at 0200 hours. All blacklists will be updated at 0300 hours. Croissants will be updated at 0400 hours (when necessary). All rules will be updated at 0500 hours. Ubuntu will be updated at 0600 hours (it will auto reboot when necessary).

non 24/7

Croissants can be turned off and it is not required to operate 24/7. The update will be carried out within half an hour when the Croissants is booting up. The Croissants may be reboot itself when necessary. It is advised not to turn off the Croissants between 0300 and 0600 hours as it will do the update automatically. If you do so, you may break the Croissants. Meanwhile, if you turn off the Croissants within half an hour of the booting up, you may also break the system too.

(6) How many detecting / blocking rules in Croissants?

There are more than 40,000 rules in Croissants and they are all free of charge. The number of rules are increasing.

(7) Do you recommend to access Croissants via SSH in internet?

For security purpose, it is not recommended to connect Croissants via SSH in internet. However, you may connect Croissants via SSH in intranet.

(8) Can Croissants decrypt the SSL/TLS traffic?

Croissants cannot decrypt the SSL/TLS traffic well. However, it can handle a limited SSL/TLS traffic flow. Therefore, it is not ideal for using it as Web Application Firewall (WAF). For example, Croissants can detect and drop self signed SSL/TLS certificate traffic and etc.

(9) How about Croissants is turned off for a week or longer?

It is recommended to run the install script once again to keep the Croissants up-to-date.

6.0 To-Do-List

6.1 Upgrade to Ubuntu Server 24.04 LTS


7.0 See Also

Besides, your server or desktop is required to be hardening on SSH, Web application and other applications as well as your desktop’s browser, etc when necessary. It is because that Croissants is not a silver bullet.

Minisforum Elitemini HM80 is a Mini PC that ideal for home based or SOHO based Intrusion Detection and Prevention System (IDPS). An external USB Ethernet dongle is required for the management purpose. It comes with AMD Ryzen R7-4800U (8-core with 16 threading) CPU and the memory can be up to 64GB.

When installing Linux with USB dongle, you are required to use Front Panel USB ports instead of Rear ones. You may need to add “iommu=soft” to the Grub in order to use the Rear Panel USB ports for the later.

8.0 Bug Fixed


9.0 Known Issues


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