brute force ssh attacks

[Man-wai Chang]

On 2/7/2019 11:36 PM, Lonni J Friedman via Linux-users wrote:
> For the past few days some bot net has decided to attempt to attack
> sshd on one of my systems with some kind of brute force attach.  Its
> coming from literally a broad swadth of the internet with connection
> attempts like this in the past 24 hours:
> .... 
> Are there any other good solutions for preventing this sort of thing
> beyond blocking sshd from everywhere except white listed IP addresses?

Port-knocking? :)