Difficult to know for sure, withouth solid papers or solid other proofs on background.
Also, a good photo on his side would be nice, to see exactly his markings.
An educated guess he is shorthair domestic, red mackerel tabby with white. That guess not mainly on the looks, which is grandiose! but the great majority of cats are "domestics", not belonging to any especial breed, but the gene pool as such, does contains lotsa of different genes and looks...
Most cats at least in my area are domestic cats--"mutt" cats, basically. We describe them first by the length of the coat--Domestic Short, Medium, or Long Hair (DSH, DMH, DLH) and then by the coloring. So I would call your boy DSH red tabby/white. Some people call them orange tabbies, I'm not sure what the technical term is. Red tabbies range from very red to rather orange, and then there is a diluted version called buff that is more apricot through cream. Tabby (the pattern of stripes characterized by the M on the forehead) can come in classic, which is kind of swirly especially around the haunches, or mackerel, which is striped like a fish skeleton, hence the name. I've seen broken mackerels too where the lines don't connect properly.
Re: the knob on his tail, it is probably related to a bone kink, either from having tail broken previously or having the tail kinked in utero. I do not know of any cat breed that characteristically has that--there are bob-tailed cat breeds such as the Manx and the Japanese Bobtail but they have short tails, sometimes only a few vertebrae long.
If you look at the photo of him laying on his side and fuzz up your eyes a little, he looks like he might be wearing tighty whities. He has very cool markings.
We have a dilute red tabby running around on our block that I have nicknamed "Mr. Beige" because I didn't realize they were dilute reds that looked "cream." I am a little embarrassed about this.