**d4-goclient** is a D4 project client (sensor) implementing the [D4 encapsulation protocol](https://github.com/D4-project/architecture/tree/master/format).
The client can be used on different targets and architectures to collect network capture, logs, specific network monitoring and send it
back to a [D4 server](https://github.com/D4-project/d4-core).
For more information about the [D4 project](https://www.d4-project.org/).
# Installation
Fetch d4-goclient code and dependencies
```bash
go get github.com/D4-project/d4-goclient
```
## Dependencies
- golang 1.13 (tested)
# Use
## Launch a d4-server (if you don't have a server)
See https://github.com/D4-project/d4-core/tree/master/server
$IP_SRV being the d4-server's address, $PORT its listening port
## Configuration files
Part of the client configuration can be stored in folder containing the following files:
- key: your Pre-Shared-Key
- snaplen: default is 4096
- source: stdin or d4server
- destination: stdout, [fe80::ffff:ffff:ffff:a6fb]:4443, 127.0.0.1:4443
- type: D4 packet type, see [types](https://github.com/D4-project/architecture/tree/master/format)
- uuid: generated automatically if empty
- version: protocol version
- rootCA.crt: optional : CA certificate to check the server certificate
- metaheader.json: optional : a json file describing feed's meta-type [types](https://github.com/D4-project/architecture/tree/master/format)
If source is set to d4server, then one also 2 additional files:
- redis_queue: redis queue in the form analyzer:typeofqueue:queueuuid, for instance `analyzer:3:d42967c1-f7ad-464e-bbc7-4464c653d7a6`
- redis_d4: redis server location:port/database, for instance localhost:6385/2
## Flags
```bash
-c string
configuration directory
-cc
Check TLS certificate against rootCA.crt
-ce
Set to True, true, TRUE, 1, or t to enable TLS on network destination (default true)
-cka duration
Keep Alive time human format, 0 to disable (default 30s)
-ct duration
Set timeout in human format
-rl duration
Rate limiter: time in human format before retry after EOF (default 200ms)
-rt duration
Time in human format before retry after connection failure, set to 0 to exit on failure (default 30s)
-v Set to True, true, TRUE, 1, or t to enable verbose output on stdout
```
## Pipe data into the client
In the followin examples, destination is set to stdout.
### Some file
```bash
cat /proc/cpuinfo | ./d4-goclient -c conf.sample/ | socat - OPENSSL-CONNECT:$IP_SRV:$PORT,verify=0
```
### tcpdump (libpcap) output, discarding our own traffic
$IP being the monitoring computer ip
```bash
tcpdump not dst $IP and not src $IP -w - | ./d4-goclient -c conf.sample/ | socat - OPENSSL-CONNECT:$IP_SRV:$PORT,verify=0
```
## Forwarding data from a D4 server to another D4 server
Add two files to you configuration folder: `redis_d4` and `redis_queue`:
- `redis_d4` contains the location of the source d4's redis server database, for instance `127.0.0.1:6380/2`
- `redis_queue` contains the queue to forward to the other D4 server, for instance `analyzer:3:d42967c1-f7ad-464e-bbc7-4464c653d7a6`