This article was first written in May 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/262).
On UNIX, the ports < 1024 are accessible to user
root only.
That has many implications, as then most
standard networked servers have to start as root anyway, because they use well-known ports (like HTTP, SMTP, POP, IMAP, FTP, …).
To reduce the risk, most of them then start as
root, open the port(s) they need and then change to another user. For example,
Apache does it like this.
