I have a Ubuntu server with 128 ip's (static external ips 86.xx.xx.16), and I want to crawl pages thru different ip's. The gateway is xx.xxx.xxx.1, the main ip is xx.xxx.xxx.16, and the other 128 ip's are xx.xxx.xxx.129/255. I tried this configuration in /etc/network/interfaces but I doesn't work. It work if I remove the gateway for the aliases eth0:0 and eth0:1. I think this is routing problem.

auto lo
iface lo inet loopback

auto eth0
auto eth0:0
auto eth0:1

iface eth0 inet static
address xx.xxx.xxx.16
netmask 255.255.255.128
gateway xx.xxx.xxx.1

iface eth0:0 inet static
address xx.xxx.xxx.129
netmask 255.255.255.128
gateway xx.xxx.xxx.1

iface eth0:1 inet static
address xx.xxx.xxx.130
netmask 255.255.255.128
gateway xx.xxx.xxx.1

Also, please tell me how to "reset" every changes that I made in networking and routing.

Thank you