Testing if a port can be reached, using built-in tools other than 'good old telnet'
There are in fact many tools which can help with this task, some of which will be familiar to those on *nix systems, but Windows users who've been around a while (or who learned from such folks) may try to rely on the good ol' telnet command (as in telnet [machine] [port]). Unfortunately, they often find out how Microsoft has disabled that tool by default for over a decade (since Windows Vista), and while it can be easily enabled, they may be prevented or understandably reluctant to do that.
In this post, I want to show a couple of command-line alternatives which can do the job easily, one best suited for powershell users (Test-NetConnection), and and two of which would suit those who prefer the command line (cmd) and which are now built-into Windows (the past few years): ssh and curl. No, this is not their primary job but they will suit for this task and it may surprise some to learn they're even built-in options. I'll conclude with still other options available to those on *nix environments (who of course can also use ssh and curl), especially nc (netcat).
