Thanks for the pointers to atrpms. I'm not sure why I missed the hit googling on "fedora nessus rpm". Of course, that's an older version (but I would probably have settled for it if I had found it like I should have.) And as for "yum install openssl-devel" I could swear I tried that, and came up empty. But now it has worked. And now I'm getting another error (about lex and flex)... So I press on.
