#Veth netmap full
#Veth netmap software

#Veth netmap software

When it starts, the detection software calls the kernel to configure a packet acquisition method. Its function is crucial for server security, but totally counterproductive if it results in the inability of the probe to fulfill its role. This is a DMA write manager, capable of limiting the memory ranges that a server’s devices can write to, much like a firewall limits access to a network. Besides possible hardware slowness on the communication buses themselves, the main cause of slowness is the filtering of memory accesses by the IOMMU (I/O Memory Management Unit). This is done by DMA (Direct Memory Access) writes or variants, such as IOAT/DMA (I/O Acceleration Technology DMA).Ī network card can saturate its queue, if it cannot perform DMA writes as fast as packets arrive from the network. The queue is then consumed by a process that transfers the packets to the server’s main memory.

Each packet that enters the card is inserted into this queue. Network cards have a relatively small internal memory this is a queue. This can happen as early as the network card receiving the packets and not being able to broadcast them to the kernel, or later, somewhere in the kernel or in the detection software itself. Received packets can be dropped by many hardware or software components, as soon as a budget overhead occurs. Where and how traffic is dropped is determined by the location of the bottleneck. If the spike in activity continues, the probe has no choice but to discard traffic. This is because some packets are processed faster than others, such as those that are immediately discarded because they are part of an encrypted stream for which the probe does not have the decryption key. If it is only a spike in traffic, it is usually possible to absorb it by smoothing the cost over the following milliseconds/seconds. This impact is particularly noticeable during packet recopies between hardware or software components.Īs soon as a probe exhausts its budget for processing one packet, the budget for subsequent packets may suffer. The latter has an impact on the packet transfer times between the various components of the probe. However, the number of bytes per second remains significant. As a result, like many pieces of equipment, it is easy to drown a probe in a lot of packets representing extremely low byte-per-second traffic. Just as an engineer is less productive if he is constantly interrupted, a CPU loses time with each interruption. Furthermore, the number of packets per second influences the number of interrupts (hardware or software) that a CPU has to process. One million packets per second means that the probe has one millionth of a second to process each packet on average. The number of packets per second is significant, as it defines the time budget available for packet processing. This throughput is expressed in two units: the number of packets per second, and the number of bytes per second. The non-adjustable variable is, in fact, the incoming flow in a probe. However, these resources are ultimately limited to the time required to process an incoming packet. It is usually possible to make some computation/memory trade-offs to optimize processing. These resources include computing capacity (CPU, FPGA, ASIC) and memory (RAM, working memory of peripherals, etc.). These are in finite quantity and depend on the hardware on which the detection and analysis mechanisms are installed. The various analysis engines that make up a probe consume machine resources. This aspect is, indeed, particularly significant since the detection rate of a probe decreases if it is submerged, even if it is equipped with the best signatures and analysis engines. This article provides feedback on the evaluation of probes, particularly from a performance perspective. The security and network engineers who have to integrate these sensors do not have any guidelines for testing their effectiveness in production. Unfortunately, the evaluation methodology for these sensors is not public.

#Veth netmap full

Operators of vital importance (OIV), operators of essential services (OSE) and, in general, organizations operating sensitive functions thus have trusted French products: Cybels Sensor by Thales and Trackwatch Full Edition by Gatewatcher. In April 2019, the ANSSI qualified the first sensors to provide network security supervision. Published on Connect (Diamond) by Florian Maury/Gatewatcher.