sftp is an ftp replacement that runs over an ssh tunnel. Two programs
are included - sftp and sftpserv. When sftp is run and a host is
connected to (either by running 'sftp remotehost' or 'open remotehost'
from the sftp prompt), an ssh connection is initiated to the remote
host, and sftpserv is run. So, sftpserv must be in your path on
the remote host. Note that since sftpserv is run from ssh, no root
privileges are necessary.