Netassertv2-l4-client

The Netassertv2-l4-client is a Go program designed to open TCP / UDP connections toward a specified destination and send a configurable string payload.

A test comprises one or more connection attempts, and a passed test results in the client exiting with a status code of 0 (1 otherwise).

You can pull the latest Docker image from docker.io/controlplane/netassertv2-l4-client:latest

Configuration

The client accepts the following environment variables:

Environment Variable	Go Type	Default Value	Purpose
TARGET_HOST	string		The target host to test (mandatory), it can be an IP or a domain name
TARGET_PORT	uint16		The target port to test (mandatory)
PROTOCOL	string	tcp	Protocol, tcp or udp
MESSAGE	string	defaultmessage	The string to use as payload
PERIOD	uint	5000	Interval between connections in milliseconds
TIMEOUT	uint	2000	Period of time in milliseconds after which the connection is considered failed
ATTEMPTS	uint	1	Number of connections to create (regardless of their failed / successful statuses)
SUCCESS_THRESHOLD	uint	80	Percentage of successful connections above which the whole test is considered passed
LOG_LEVEL	string	info	Log level, available: (debug, info, warn, error)
LOG_ENCODING	string	console	Log encoding, available: (console, json)

Parameters can also be passed as command line arguments. These take precedence over environment variables in case both are defined for the same parameter. Command line args are named as lowered-case environment variables and with "-" replaced by "_".

Build and Run

Build the client:

make build

And run it providing at least a target host and a port, for example:

./bin/netassertv2-l4-client --target-host 192.168.1.10 --target-port 8443

If the host is not reachable and / or there is not a service listening on the specified port, the connection(s) will fail.

Multiple connections can run in parallel, for example when connections fail due to timeout and the period parameter is less than timeout, or, more in general, if a connection takes more than period to complete.

Example

A valid host can be created using netcat in server mode:

while true; do nc -vl localhost 12345; done

On a different tab, run the client:

./bin/netassertv2-l4-client --target-host=localhost --target-port=12345 --attempts 3 --message $'examplemessage\n'

Client output:

2023/03/09 15:49:38 maxprocs: Leaving GOMAXPROCS=16: CPU quota undefined
2023-03-09T15:49:38.166+0100	INFO	cobra@v1.6.1/command.go:916	&{LogLevel:info LogEncoding:console Protocol:tcp TargetHost:localhost TargetPort:12345 Message:examplemessage
 Timeout:2000 Attempts:3 Period:5000 SuccThrPec:80}
2023-03-09T15:49:38.168+0100	INFO	runtime/asm_amd64.s:1598	successful connection and data sent to localhost:12345
2023-03-09T15:49:43.171+0100	INFO	runtime/asm_amd64.s:1598	successful connection and data sent to localhost:12345
2023-03-09T15:49:48.170+0100	INFO	runtime/asm_amd64.s:1598	done creating connections
2023-03-09T15:49:48.171+0100	INFO	conntester/conntester.go:93	waiting for connections to stop...
2023-03-09T15:49:48.172+0100	INFO	runtime/asm_amd64.s:1598	successful connection and data sent to localhost:12345
2023-03-09T15:49:48.172+0100	INFO	conntester/conntester.go:93	all connections have finished
2023-03-09T15:49:48.173+0100	INFO	runtime/asm_amd64.s:1598	success rate of: 100
2023-03-09T15:49:48.173+0100	INFO	runtime/asm_amd64.s:1598	success rate greater than threshold: 80
2023-03-09T15:49:48.173+0100	INFO	cobra@v1.6.1/command.go:916	jobs stopped
2023-03-09T15:49:48.173+0100	INFO	cobra@v1.6.1/command.go:916	test passed

Netcat output showing the "examplemessage" received:

Listening on localhost 12345
Connection received on localhost 33226
examplemessage
Listening on localhost 12345
Connection received on localhost 33228
examplemessage
Listening on localhost 12345
Connection received on localhost 55004
examplemessage
Listening on localhost 12345