...The one I'm thinking of (but don't remember the name)...
There's probably a lot of these- it could be
pureftpd that you're thinking of (or it could be something else!)
From their splash page:
Pure-FTPd is actively supported, and it was always designed with security in mind, and the code is always re-audited as new kind of vulnerabilities are discussed. Unlike other popular FTP servers, the number of root exploits found since the very first released version is zero.
setenv EXINIT 'set noai ts=2'