Root privilege

For various complex reasons, rsh, rlogin, and rcp need to set network connections as root.

They’re horribly insecure for network reasons.

How to use root privilege?

• We only need root privileges to set up the connection.
• Use an external program for using root to set up connection.
  • Method 1: pass an open file descriptor back.
  • Method 2: Fork and pay the price of extra data copies.