mirror -- A Perl program for mirroring FTP sites.
http://sunsite.doc.ic.ac.uk/packages/mirror/
Mirror uses the FTP protocol to duplicate a directory hierarchy between
its local host and a remote host. Mirror avoids unnecessarily copying
files by comparing the file timestamps and sizes before transfer. Mirror
is also optionally capable of compressing, gzipping and splitting files.
Mirror was written for the use of archive maintainers but can be used
by anyone who needs to transfer a large number of files via FTP.