# abstract

nDPId is a set of daemons and tools to capture, process and classify network flows.
It's only dependencies (besides a half-way modern c library and POSIX threads) are libnDPI (>= 3.3.0) and libpcap.

The core daemon nDPId uses pthread but does use 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 hash value is calculated using the 5-tuple.
This value serves as unique identifier for the processing thread. Multithreaded packet processing has to be flow-stable.

nDPId uses libnDPI's JSON serialization to produce meaningful JSON output which it then sends to the nDPIsrvd for distribution.
High level applications can connect to nDPIsrvd to get the latest flow/packet events from nDPId.

Unfortunately nDPIsrvd does currently not support any encryption/authentication for TCP connections.
TODO: Provide some sort of AEAD for connecting distributor clients via TCP (somehow very critical).

# architecture

This project uses some kind of microservice architecture.

```text
_______________________                                         __________________________
|     "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 >|  `- connect to UNIX socket           |  |                        |
| (eth1) `- Thread 2 >|  `- sends serialized data            |  |< example/...           |
|        `- Thread N >|                                      |  |________________________|
|_____________________|                                      |                            
                                                             `- connect to UNIX/TCP socket
                                                             `- receives 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
0015{"key":"value"}
```
where `0015` describes the length of a **complete** JSON string.

TODO: Describe data format via JSON schema.

# build

To get an overview over all build options, run:
```shell
make help
```

To build nDPId and nDPIsrvd, run:
```shell
make all
```

To build nDPId and nDPIsrvd with sanitizer, debug mode enabled and a custom/not-your-distro libnDPI, run:
```shell
make ENABLE_DEBUG=yes ENABLE_SANITIZER=yes CUSTOM_LIBNDPI=[path-to-libndpi].[a|so] all
```

To build nDPId and nDPIsrvd and examples, run:
```shell
make all examples
```

# run

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

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

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

or
```shell
./examples/c-json-stdout/c-json-stdout
```

or anything below `./examples`.