I have a Linux router with 3 NICs. eth0 is my WAN interface, eth1 is my LAN, and eth2 is a DMZ with some web servers on it. On eth0, I have an IP address, and 5 virtual interfaces, to answer requests to addesses in a public /29 block I have. I then route these to machines in my DMZ. I have run out of addresses, and my ISP has issued me another block of IPs, a /29 in a different location on my ISP's IP allocation. My question is, can I assign this new block of addresses to virtual interfaces on eth0, in addition to my existing addresses? I'm 99% sure I can, but since I'm live, I can't be making changes willy nilly without knowing what to expect.

yes u can use and the new block will try to use your defaul GateWay