Cybersecurity

When SNIs Cannot be Trusted
SNI (Server Name Indication) is an optional extension in TLS/QUIC that contains the symbolic host name we’re connecting to. For instance, during the TLS handshake, the SNI allows the server to identify the correct TLS certificate of a server hosting multiple websites. nDPI reports SNIs in order to make it possible to detect name-based services deployed on the same server IP address. Below you can see an example of how nDPI reports SNIs in encrypted traffic. Client applications use the SNI to verify that the website it is connecting to matches …
Technologies and Trends

Announcing ntop Professional Training: November 2025
ntop tools range from packet capture, traffic analysis and processing, and sometimes it is not easy to keep up on product updates as well master all the tools. This has been the driving force for organising ntop professional training. This is to announce that in October we have scheduled the next ntop Professional Training session. It will take place online (Microsoft Teams) on 13th, 18th, 20th, 25th, 27th of November, 2025 at 3.00 PM CET (9.00 AM EDT). Training will be held in English language and each session lasts 90 …
cento

Handling High Flow Rates: Cento and ntopng at Scale
Cento is a high-speed NetFlow probe designed to analyse traffic from high-speed links (100+ Gbit/s) and export flows toward ntopng, third party collectors or big-data systems. When exporting data to ntopng, Cento uses ZeroMQ (ZMQ) as its primary mechanism for exporting flows in JSON or binary (TLV) format. In short, Cento acts as a ZMQ publisher, sending flow records over a TCP socket. ntopng subscribes to this socket as a ZMQ collector, receiving and processing the flows in real-time. This design allows flexible network deployment, with Cento running on the …
ntopng

AS Traffic Observability using ntopng
Since the first version of our tools, we have focused on packets. Having access to packets is a privilege that is not always possible; observing packets provides high-detailed information. At the edge of the Internet, traffic received/sent by hosts can be captured and observed, but in the case of network operators that act as a transit from the customers to the Internet, observing packets is not a good practice. This is because network operators need to make sure the service is available, but without going too deep. For this reason, network operators usually leverage NetFlow/IPFIX, sometimes …
Technologies and Trends

Breaking Free from Packet Brokers: How to Use nTap/PF_RING ZC for Traffic Aggregation
nTap is a lightweight software-based network tap designed by ntop to simplify remote traffic collection and analysis. Unlike traditional hardware-based packet brokers, nTap lets you capture, forward, and aggregate traffic using pure software—reducing complexity and cost. In this blog post, we’ll walk through: nTap fundamentals (FAQ highlights) Step-by-step configurations for popular use cases Integration with n2disk, nProbe, and ntopng Scaling from low (1 Gbps) to very high-speed (40/100 Gbps) deployments Best practices for performance optimization nTap FAQ Highlights Q: What is the network overhead introduced by nTap?Each captured packet incurs …
ntopng

Introducing ntopng Alerts Graph: Visualize Security Events Like Never Before
Network security analysts often struggle to understand how alerts are connected across different hosts. Traditionally, ntopng displayed flow alerts in a table format, perfect for listing issues, but limited when it comes to spotting patterns or identifying which host is the real problem or victim. Additionally, tabular visualization does not let security analysts or network managers quickly determine which problem to tackle first, causes alert fatigue what are the main network issues, such as brute force attempts, obsolete TLS or SSH version connections, periodic flows etc. These issues are now …
nDPI

Beyond JA3/JA4: Introducing nDPI Traffic Fingerprint
Traffic fingerprinting is a hot topic and we have discussed it several times both in this blog and at conferences. There are various fingerprints techniques and probably most of you know JA3/JA4. Let me do a short recap on the subject in nDPI we support several de-facto fingerprint such a JA4 and additional nDPI-native such as the OS (Operating System) fingerprint. In our research we have realized that in cybersecurity using a single fingerprint (e.g. JA4) leads to too many false positives making it a “nice to have” rather than …
Data Privacy

Export and Archive ClickHouse Flows in ntopng for Regulatory Compliance
Most ntopng users make extensive use of ClickHouse support for storing historical flow data and running analysis on it. ClickHouse is highly optimized and offers a high compression rate (estimated at an average of 60 bytes per flow), allowing for long data retention even with limited storage. However, to comply with regulations such as GDPR, SOX, HIPAA, and PCI DSS, it is often necessary to retain data for extended periods. This is manageable when flow rates are low to moderate, but can require significant disk space when flow rates are …
nProbe

Best Practices for nProbe and ntopng Deployment
We often receive inquiries about the best practices for deploying nProbe and ntopng. This post will try to shed some light on this subject. The first thing to know is how many flows/second in total the nProbe instances will deliver to ntopng.  nProbe Flow CollectionEach nProbe instance can collect a high number of flows (in the 50/100k flows/sec range depending on hardware and flow types), but we typically suggest loading balance flows across multiple instances. Ideally, each nProbe instance should handle no more than 25k flow/sec. As ntop licenses are …
ntop

New, Fast, Scalable ClickHouse Integration for High-Volume Networks
When it comes to monitoring very large networks and the flows’ cardinality reaches into the billions, the performance of historical data storage and query systems becomes a critical bottleneck. Network operators, analysts, and engineers need to access flow records quickly and reliably, whether for traffic analysis, security investigations, or compliance reporting. When faced with massive datasets, even small inefficiencies in the data pipeline can result in slow queries, high CPU and disk usage, and poor responsiveness. At ntop, our mission is to help users gain visibility into their networks with …
ntop

Network Visibility and Observability: ntopng vs SNMP+
Recently, we’ve encountered users with high monitoring requirements. Some users need to monitor 1,000 routers and want to know who are the top talkers or top protocols. Others have a network with 200 branches, each with a NetFlow-enabled router. They need to know from a central location who are the top bandwidth users and ports on selected branches. Essentially, these users don’t need fine-grained network traffic monitoring. They just need a rough idea of who the top network users are (IP and ports). Often, users who ask us these questions …
ntop

HowTo Monitor+nDPI Traffic on Mikrotik Devices Using TZSP
Mikrotik devices are very popular in the ntop community. The simplest way to monitor traffic of these devices is using flows as described in this blog post. However sometimes flows might not be the best choice for various reasons including the inability to perform DPI on the captured traffic.  For full visibility you can use a different option offered by Mikrotik devices. Under Tools -> Packet Sniffer  you can export packets over the TZSP protocol (it is a sort of remote span protocol): just specify the IP of the remote …

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