Bark scraped off base of the base of an ash tree - prevention?

I suspect that a grey squirrel is doing this.

The tree is fairly old so the trunk is maybe two feet in diameter and it's a healthy ash tree, the two areas with the scraped off bark are maybe 3 or 4 inches in diameter in vertical strips but I want to prevent any further damage.

I also don't want to harm the squirrels, so what is the best way to prevent them damaging the bark?

At the moment this is limited to the very base of the trunk, about the bottom foot or so, but will they instead scrape higher up if just the base is protected?

Should I perhaps wrap some chicken wire around the trunk, or some other covering that will still allow airflow?

Or is there some kind of protective solution that I can paint onto the trunk that won't be washed away by rain?