If you search for a feature rich backup script working on linux, give glsysbackup a try. It is still under active developement and is available on github:
https://github.com/ccztux/glsysbackup
Append the following function to: /etc/profile and modify the variable: proxy to fit your requirements:
#!/bin/bash
###########################################################################################
#
# Author: ccztux
# http://www.linuxinside.at
# 2011-12-28
#
# Last Modification: ccztux
# http://www.linuxinside.at
# 2013-02-11
#
# Description: Find out public IP.
#
# Changelog: 1.0 Initial revision
# 1.1 Bugfix: chkRC
# 1.2 Verbose output added
# 1.3 whatismyip.org-address changed
# 1.4 changed whatismyip.org to ifconfig.me
# 1.5 script reworked, chkInetConn added
#
# License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
#