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Version: v4.18

tcp

Loads bytes from a TCP or TLS connection.

Synopsis

Loader:

tcp [-c|--connect] [-o|--listen-once]
[--tls] [--certfile] [--keyfile] <endpoint>

Saver:

tcp [-l|--listen] [-o|--listen-once]
[--tls] [--certfile] [--keyfile] <endpoint>

Description

The tcp connector supports TCP or TLS connections. The loader reads blocks of bytes from the socket, and the saver writes them to the socket.

The loader defaults to creating a socket in listening mode. Use --connect if the loader should initiate the connection instead. The saver defaults to creating a socket in connect mode. Use --listen if the saver should instead listen on a socket.

When you have a socket in listening mode, use 0.0.0.0 to accept connections on all interfaces. Both saver and loader also have a --listen-once option that will stop the pipeline after the first connection terminated. The nics operator lists all all available interfaces.

One connection at at time

A single pipeline can accept at most one TCP connection at a time. If another client attempts to connect to the same listening socket, it will time out. The reason for this behavior is that the downstream operator (typically a parser) may exhibit undefined behavior if it receives data from multiple sockets.

<endpoint>

The address of the remote endpoint to connect to when using --connect, and the bind address when using --listen.

-c,--connect (Loader)

Connect to <endpoint> instead of listening at it.

-l,--listen (Saver)

Listen at <endpoint> instead of connecting to it.

-o,--listen-once

When listening to a socket, only process a single connection instead of looping over all connecting clients forever.

Requires a loader or saver with --listen.

--tls

Wrap the connection into a TLS secured stream.

--certfile

Path to a .pem file containing the TLS certificate for the server.

Ignored unless --tls is also specified.

--keyfile

Path to a .pem file containing the private key for the certificate.

Ignored unless --tls is also specified.

Examples

Read raw bytes by connecting to a TCP endpoint:

load tcp://127.0.0.1:8000

Test this locally by spinning up a local server with socat:

echo foo | socat TCP-LISTEN:8000 stdout

Listen on localhost and wait for incoming TLS connections:

load tcp://127.0.0.1:4000 --tls --certfile key_and_cert.pem --keyfile key_and_cert.pem -k

The above example uses a self-signed certificate that can be generated like this:

openssl req -x509 -newkey rsa:2048 -keyout key_and_cert.pem -out key_and_cert.pem -days 365 -nodes

Test the endpoint locally by issuing a TLS connection:

openssl s_client 127.0.0.1:4000