OpenSSH: option named 46AaCfGgKkMNnqsTtVvXxYy

Question

With the 2017 Fall Creators Update, Microsoft added a version of OpenSSH to Windows 10, which got out of beta and is enabled by default in the recent April Update.

Today I tried to take it for a spin and saw that its usage page lists an option named 46AaCfGgKkMNnqsTtVvXxYy. usage: ssh -46AaCfGgKkMNnqsTtVvXxYy.

Upon running the above command. PowerShell prints the following output:

PS C:\WINDOWS\system32> ssh -46AaCfGgKkMNnqsTtVvXxYy
OpenSSH_for_Windows_7.6p1, LibreSSL 2.6.4

This looks like a version number of sorts.

I have looked in the Microsoft Docs to find more information about ssh and this flag, but to no avail. A documentation page on this website shows the option, but doesn't explain what it should do. To me, it looks like a combination of multiple options, but that doesn't explain why it outputs a version number.

My questions are the following:

1. Is it normal for ssh to have an option with such a peculiar name?
2. If yes, where does it originate from?
3. Is this the expected output for this command?

Is anyone able to provide some more insight on this?

Answer 1

As you can see from the site you linked to they are separate options, not a single option. -4 means one thing, -6 another etc. The reason they’re in one blob is because they don’t take any parameters and they can be combined, meaning -4A would be the same as -4 -A. This saves space on manual pages but is confusing unless you know about it.

After them are all the optiona that do take parameters, like -B.

The version number is shown because -V shows version number and exits and is included there.