setlocal iskeyword=@,48-57,_,192-255,#,-
syntax match knownhostspubkey "AAAA[a-zA-Z0-9+/]\+[=]\{0,2}"
highlight def link knownhostspubkey Special

syn keyword sshalg ssh-rsa
hi def link sshalg Identifier

syn match knownhostsip "\<\(\d\{1,3}\.\)\{3}\d\{1,3}\>"
hi def link knownhostsip Constant