#!/usr/bin/env bash +x

## Do you need to test your exposed app but you don't have curl/wget/* installed?

## Simple and easy
:> /dev/tcp/localhost/22

## Why using timeout? If any side has a firewall and it's dropping the packages, the request will take ~80 seconds to get the timeout.

## Let's try first with Google :D
## In this case, we don't have output, but the return code will be 0
timeout 10s bash -c ':> /dev/tcp/google.com/443'
## Return code
0

## Now let's try locally. With return code 1
timeout 10s bash -c ':> /dev/tcp/localhost/443'
## Output
bash: connect: Cannot assign requested address
bash: /dev/tcp/localhost/443: Cannot assign requested address
## Return code
1