EP2476237A1

EP2476237A1 - Supervision of a communication session comprising several flows over a data network

Info

Publication number: EP2476237A1
Application number: EP10763796A
Authority: EP
Inventors: Jérôme TOLLET; Jérôme ABELA
Original assignee: Qosmos
Current assignee: Qosmos Tech
Priority date: 2009-09-09
Filing date: 2010-09-01
Publication date: 2012-07-18
Also published as: JP2013504915A; KR101703805B1; CA2773247A1; KR20120082415A; CN102714652B; WO2011030045A1; CN102714652A; FR2949934A1; JP5696147B2; US20120166666A1; FR2949934B1; SG179043A1

Abstract

The invention relates to a method for supervising a communication session over a data network, said session including a first data flow, referred to as the parent flow, using a first protocol, said parent flow including data suitable for setting up a second data flow, referred to as the child flow, using a second protocol for said session, which includes: searching (13) the parent flow for the data that enable the child flow to be set up; generating (15) and storing (17) a signature, referred to as a parent key, using said data; auditing (19) data flows using the second protocol on the data network; creating (21) a signature for each one of the flows; comparing (23) said signature of each one of the flows with the parent key; and, if the comparison is positive, determining (25) that the data flow in question is the child flow of the session.

Description

MONITORING A COMMUNICATION SESSION COMPRISING MULTIPLE STREAMS ON A DATA NETWORK.

The present invention relates to a method and a system for monitoring a communication session on a data network, said session comprising a first data stream, called a parent stream, using a first protocol, said parent stream comprising data enabling establishing a second stream of data, said child stream, using a second protocol for said session. It also relates to a computer program product for implementing the monitoring method.

Current network applications typically use more than one session and protocol to perform their task.

For example, during a video call generated by the setting up of a video conference, a real-time protocol (RTP) session will be initiated by a Session Initiation Protocol (SIP) session. session initialization), and the parameters of the RTP session will depend on information exchanged by the SIP session.

Network monitoring devices, such as, for example, firewalls, link the sessions of different protocols via state machines.

This solution has the disadvantage of making these devices complex because it is necessary, in particular, to write the behavior of a state machine for each new network application. In addition, the processing of the different streams can be very resource-consuming, which limits the bandwidth available through these devices, or requires the development of expensive machines or to limit the amount of data monitored.

It would therefore be advantageous to obtain a method and a monitoring system for monitoring network applications using many protocols with greater efficiency in terms of hardware resources and implementation.

To solve one or more of the aforementioned drawbacks, a method of monitoring a communication session on a data network, the session comprising a first stream of data, said parent stream, using a first protocol, the parent stream comprising data enabling the establishment of a second data stream, said child stream, using a second protocol for this session, comprises:

· Search in the parent stream for data allowing the establishment of the child stream;

• generate and store a signature, called parent key, from these data;

• auditing data flows using the second protocol on the data network;

• create a signature for each stream;

• compare the signature of each stream to the parent key; and

• If the comparison is positive, determine that the corresponding data flow is the child flow of the session.

By defining each stream by a suitable signature, and by making a simple comparison of signatures, a computer operation that is simple and fast, this method advantageously makes it possible to easily group the related streams, and in particular without defining a state machine.

Particular characteristics or embodiments that can be used alone or in combination are:

The session comprising a determined plurality of child flows, the data flows are audited until the set of child flows is determined.

The child stream including data for establishing a third data stream using a third protocol for the session, a signature is generated from these data, and data streams using the third protocol are audited to determining the data flow corresponding to the session.

The method monitoring a plurality of sessions each comprising a parent stream for which a parent key is generated and stored, for each of the streams using the second protocol, the The signature is compared to each of the parent keys to determine whether the stream is, or not, the child stream of one of the sessions. It should be noted in particular that this method advantageously applies to a multitude of parent flows, child flows and any type of tree defining an inheritance between one or more parent flows, one or child flows with any level of information. 'legacies.

In a second aspect of the invention, a computer program product includes program code instructions recorded on a computer readable medium, for implementing the steps of the preceding method when said program is running on a computer.

In a third aspect of the invention, a system for monitoring a communication session on a data network, the session comprising a first data stream, called a parent stream, using a first protocol, the parent stream comprising data enabling establishing a second stream of data, said child stream, using a second protocol for the session, comprises:

A first stream analyzer for searching the parent stream for the data enabling the child stream to be established;

• a first signature generator, called parent key, from these data;

• a storage memory of the signature;

A second stream analyzer for auditing data streams using the second protocol on the data network;

A second signature generator for each of these streams;

· A comparator of the signature of each stream to the parent key; and

• a tagger to attach the stream corresponding to the signature, if the result of the comparator is positive, as a child stream of the session.

In particular embodiments, the system comprises at least two devices connected by a data network, a first device comprising at least the storage memory, the signature comparator and the tagger and the second device comprising at least the first analyzer the first signature generator and an interface for transmitting the generated signature to the first device. It may also include at least a third device connected to the first device by the data network and comprising at least the second flow analyzer and the second signature generator and an interface for transmitting the generated signature to the first device.

The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended figures in which:

FIG. 1 is a schematic view of a data network;

FIG. 2 is a flow chart of a method according to one embodiment of the invention;

FIG. 3 is a schematic view of a surveillance system according to one embodiment of the invention; and

- Figure 4 is a schematic view of a monitoring system according to a second embodiment of the invention.

With reference to FIG. 1, a digital data network 1 connects a multitude of devices 3 to each other. A monitoring system 5 is connected to this network to capture the data flows exchanged between the equipment 3.

The system 5 thus monitors the communication sessions running on the network 1. The term "session", or application session, is the set of data exchanges generated by a given network application.

For example, as is well known, when a first device wishes to transfer a file using a FTP protocol to a second device, the first device and the second device will start by establishing a first exchange using the TCP protocol on the port. 21 then they will agree to transfer the file itself using FTP-DATA which uses the TCP protocol on a variable number port greater than 1024. All of these exchanges constitute a session.

We will then call sub-session, or simply data stream, the first TCP exchange on port 21 on the one hand and transfer to FTP-DATA on the other hand. The first sub-session will be called parent sub-session, or parent stream, in that it allows to exchange the data between the two equipments allowing the establishment of the second sub-session which will thus be called child sub-session, or child flow.

To monitor a session, the system 5 implements the following method, FIG.

By analyzing the data transferred, the system detects, step 1 1, establishment of an application session in the form of a parent stream.

The system 5 analyzes, step 1 3, then the parent stream looking for establishment data of a child stream. For example, in the context of an FTP session, the system 5 will analyze the transmitted packets to determine the number of the port on which the file transfer will take place.

Once these data are collected, the system 5 generates, step 1 5, a signature, called parent key, from these data. For example, for an FTP session, the system 5 generates a signature from the I P addresses of the source equipment and the receiving equipment and the port number. This signature is, for example, a hash value of this data.

This parent key is stored, step 1 7, by the system 5.

The system 5 then monitors, step 1 9, the flows that can correspond to the child stream because implementing, for example, a protocol compatible with it.

For each of these flows, it calculates, step 21, a signature. The calculation of this signature is similar to the calculation of the parent key. For example, for the FTP session, it calculates the hash key of the I P addresses of the two devices and the port number.

This signature is compared, step 23, to the parent key.

If the comparison is positive, then the corresponding stream is, step 25, the desired child stream.

For explanatory purposes, the description above is limited to a parent stream and a child stream. However, the method is generalized without difficulty to a plurality of parent flows and child flows.

Thus, if a session consists of a parent stream and a plurality of child streams, the system calculates as many parent keys as necessary and monitors all flows until all child flows are found.

Conversely, several sessions, and therefore several parent streams, can be monitored in parallel.

The comparison of the flow signatures is then made on all the parent keys until a parent key matches, thus defining the attachment session. If no key matches, it means that the stream does not belong to any monitored session.

The method also applies smoothly to sessions with multiple cascading inheritances, i.e., a child stream has establishment data of another stream and behaves like a parent stream for that stream. other flow that is then its child flow. Based on the settlement data carried by the child stream, the system sets a parent key on which the signatures of the prospective child flows are compared.

The detailed implementation of the process can take different forms depending on the desired technical characteristics and the processing capabilities of the system.

For example, the set of parent keys may correspond to an ordered index vector, one of whose attributes is the session name. Once the signature of a calculated flow, the search and comparison with the parent key (s) and the allocation of the flow to a session then correspond to an operation on indexes, a computer operation that is extremely efficient in terms of resources used and speed. It also makes it possible to pool the monitoring operations of a multitude of sessions.

The monitoring system 5 thus comprises, FIG.

A first stream parser 31 for searching the parent stream for the data enabling the child stream to be established;

A first signature generator 33, called the parent key, from these data;

A storage memory 35 of the signature;

A second stream analyzer 37 for auditing data streams using the second protocol on the data network; A second signature generator 39 for each of these streams;

• a comparator 41 of the signature of each of these streams to the parent key; and

A tagger 43 for attaching the stream corresponding to the signature, if the result of the comparator is positive, as a child stream of the session.

This monitoring system is feasible in the form of a dedicated electronic circuit or by specifically programming a computer with a computer program comprising program code instructions recorded on a computer-readable medium, to implement the steps of the program. monitoring process when the program is running on a computer. This computer comprises in particular a network interface enabling it to listen to the transmissions carried out on the network, volatile random access memories connected to a computing unit to generate the keys and signatures, storage memories that can be, for example, a magnetic hard disk to store especially the rules of formation of signatures.

A particularly interesting embodiment of this system consists of breaking it up into several decentralized devices, FIG. 4. A first series of devices 50 installed closest to the streams comprises the flow analyzers 31, 37 and the signature generators 33, 39. Each then comprises a communication interface 52 with a centralization device 54 comprising, in addition to a communication interface 56 in connection with the interfaces 52, the storage memory 35 of the signatures as well as the comparator 41 of the signature and the tagger 43. The latter element can also be found in the first devices 50 in order to label the flows as close to their production.

The invention has been illustrated and described in detail in the drawings and the foregoing description. This must be considered as illustrative and given by way of example and not as limiting the invention to this description alone. Many alternative embodiments are possible.

In particular, the monitoring system may actually include only one flow analyzer and one signature generator capable of auditing feeds and generating signatures for parent feeds as well. only for child flows. Or, for reasons of speed, these can be as numerous as there are types of protocols.

In the claims, the word "comprising" does not exclude other elements and the indefinite article "one" does not exclude a plurality.

Claims

A method of monitoring a communication session on a data network, said session comprising a first data stream, said parent stream, using a first protocol, said parent stream comprising data for establishing a second data stream , said child stream, using a second protocol for said session, said method comprising:

• search (13) in the parent stream the data allowing the establishment of the child stream;

Generating (15) and storing (17) a signature, called a parent key, from said data;

• auditing (19) data streams using the second protocol on said data network;

Creating (21) a signature for each of said streams;

• comparing (23) said signature of each of said streams to the parent key; and

• if the comparison is positive, determine (25) that the corresponding data stream is the child stream of said session.

Method according to claim 1, characterized in that the session comprising a determined plurality of child flows, the data flows are audited until all the child flows are determined.

Method according to claim 1 or 2, characterized in that said child stream comprising data enabling the establishment of a third data stream using a third protocol for said session, a signature is generated from said data, and data flows. data using the third protocol are audited until the data flow corresponding to the session is determined.

Method according to any of the preceding claims, characterized in that said method monitors a plurality of sessions each comprising a parent stream for which is generated and stored a parent key, for each of said streams using the second protocol, the signature is compared to each of the parent keys to determine if said stream is, or not, the child stream of one of said sessions. A computer program product comprising program code instructions recorded on a computer readable medium, for carrying out the steps of the method according to any one of claims 1 to 4 when said program is running on a computer. A system for monitoring a communication session on a data network, said session comprising a first data stream, said parent stream, using a first protocol, said parent stream comprising data enabling the establishment of a second stream. a child stream, using a second protocol for said session, said system comprising:

A first stream analyzer (31) for searching the parent stream for data enabling the child stream to be established;

A first signature generator (33), called the parent key, from said data;

A storage memory (35) of said signature;

A second stream analyzer (37) for auditing data streams using the second protocol on said data network;

A second signature generator (39) for each of said streams;

• a comparator (41) of said signature of each of said streams to the parent key; and

A tagger (43) for attaching the stream corresponding to the signature, if the result of the comparator is positive, as a child stream of said session. 7. System according to claim 6, characterized in that it comprises at least two devices connected by a data network, a first device comprising at least the storage memory, the signature comparator and the tagger and the second device comprising at least first flow analyzer and the first signature generator and an interface for transmitting the generated signature to the first device.

8. System according to claim 7, characterized in that it comprises at least a third device connected to the first device by the data network and comprising at least the second flow analyzer and the second signature generator and an interface for transmitting the signal. generated signature at the first device.