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# abstract

nDPId is a set of daemons and tools to capture, process and classify network traffic.
It's minimal dependencies (besides a half-way modern c library and POSIX threads) are libnDPI (>= 4.2.0 or current github dev branch) and libpcap.

The daemon nDPId is capable of multithreading for packet processing, but w/o mutexes for performance reasons.
Instead synchronization is achieved by a packet distribution mechanism.
To balance all workload to all threads (more or less) equally a unique identifier represented as hash value is calculated using a 3-tuple consisting of IPv4/IPv6 src/dst address, IP header value of the layer4 protocol and (for TCP/UDP) src/dst port. Other protocols e.g. ICMP/ICMPv6 are lacking relevance for DPI, thus nDPId does not distinguish between different ICMP/ICMPv6 flows coming from the same host. Saves memory and performance, but might change in the future.

nDPId uses libnDPI's JSON serialization interface to generate JSON strings for each event which it then sends to the nDPIsrvd for distribution.
High level applications can connect to nDPIsrvd and get the latest events from nDPId.

Unfortunately nDPIsrvd does currently not support any encryption/authentication for TCP connections (TODO!).

# architecture

This project uses some kind of microservice architecture.

```text
                connect to UNIX socket          connect to UNIX/TCP socket                
_______________________   |                                 |   __________________________
|     "producer"      |___|                                 |___|       "consumer"       |
|---------------------|      _____________________________      |------------------------|
|                     |      |        nDPIsrvd           |      |                        |
| nDPId --- Thread 1 >| ---> |>           |             <| ---> |< example/c-json-stdout |
| (eth0) `- Thread 2 >| ---> |> collector | distributor <| ---> |________________________|
|        `- Thread N >| ---> |>    >>> forward >>>      <| ---> |                        |
|_____________________|  ^   |____________|______________|   ^  |< example/py-flow-info  |
|                     |  |                                   |  |________________________|
| nDPId --- Thread 1 >|  `- send serialized data             |  |                        |
| (eth1) `- Thread 2 >|                                      |  |< example/...           |
|        `- Thread N >|             receive serialized data -'  |________________________|
|_____________________|                                                                   
```

It doesn't use a producer/consumer design pattern, so the wording is not precise.

# JSON TCP protocol

All JSON strings sent need to be in the following format:
```text
[5-digit-number][JSON string]
```

## Example:

```text
00015{"key":"value"}
```
where `00015` describes the length (as decimal number) of the **entire** JSON string including the newline `\n` at the end.

A common sequence of received JSON strings could look alike (simplified):
```text
00070{"flow_event_id":1,"flow_event_name":"new","packet_id":1,"flow_id":1}
00101{"flow_id":1,"flow_packet_id":1,"packet_event_id":2,"packet_event_name":"packet-flow","packet_id":1}
00075{"flow_event_id":5,"flow_event_name":"detected","packet_id":4,"flow_id":1}
00093{"flow_event_id":2,"flow_event_name":"end","packet_id":258,"flow_id":1,"flow_packet_id":258}
```

# build (CMake)

```shell
mkdir build
cd build
cmake ..
```

or

```shell
mkdir build
cd build
ccmake ..
```

or to build with a staticially linked libnDPI:

```shell
mkdir build
cd build
cmake .. -DSTATIC_LIBNDPI_INSTALLDIR=[path/to/your/libnDPI/installdir]
```

If you're using the latter one, make sure that you've configured libnDPI with `./configure --prefix=[path/to/your/libnDPI/installdir]`
and do not forget to set the all necessary CMake variables to link against shared libraries used by your nDPI build.

e.g.:

```shell
mkdir build
cd build
cmake .. -DSTATIC_LIBNDPI_INSTALLDIR=[path/to/your/libnDPI/installdir] -DNDPI_WITH_GCRYPT=ON -DNDPI_WITH_PCRE=OFF -DNDPI_WITH_MAXMINDDB=OFF
```

Or let a shell script do the work for you:

```shell
mkdir build
cd build
cmake .. -DBUILD_NDPI=ON
```

The CMake cache variable `-DBUILD_NDPI=ON` builds a version of `libnDPI` residing as git submodule in this repository.

# run

Generate a nDPId compatible JSON dump:
```shell
./nDPId-test [path-to-a-PCAP-file]
```

Daemons:
```shell
./nDPIsrvd -d
sudo ./nDPId -d
```

or for a usage printout:
```shell
./nDPIsrvd -h
./nDPId -h
```

And why not a flow-info example?
```shell
./examples/py-flow-info/flow-info.py
```

or
```shell
./nDPIsrvd-json-dump
```

or anything below `./examples`.

# test

The recommended way to run integration / diff tests:

```shell
mkdir build
cd build
cmake .. -DBUILD_NDPI=ON
make nDPId-test test
```

Alternatively you can run some integration tests manually:

`./test/run_tests.sh [/path/to/libnDPI/root/directory] [/path/to/nDPId-test]`

e.g.:

`./test/run_tests.sh [${HOME}/git/nDPI] [${HOME}/git/nDPId/build/nDPId-test]`

Remember that all test results are tied to a specific libnDPI commit hash
as part of the `git submodule`. Using `test/run_tests.sh` for other commit hashes
will most likely result in PCAP diff's.

Why not use `examples/py-flow-dashboard/flow-dash.py` to visualize nDPId's output:

![dashboard](examples/py-flow-dashboard/dashboard.png "Plotly/Dash Example")