How to use multiple IPs on dedicated server?

Question

I have this dedicated server with /29 IPv4, and I would like to know how to use all the IPs I have avaliable. How to choose? How can I know which are the IPs? Can I use them like proxies with proxycap or proxifier?

Answer 1

You can find out what the range of addresses is with netmask -r a.b.c.d/29 which will show the range. Usually the first is the network number, the next is the router (check with your service provider although you should already have that configured), the last is the broadcast address. The 5 remaining addresses should be free to use.

You can add those addresses to your network interface. If you have a Debian-based system with /etc/network/interfaces you can add the addresses like so:

auto eth0
iface eth0 inet static
    address 192.168.1.242
    netmask 255.255.255.248
    gateway 192.168.1.241
    up ip addr add 192.168.1.243/32 dev eth0
    up ip addr add 192.168.1.244/32 dev eth0
    up ip addr add 192.168.1.245/32 dev eth0
    up ip addr add 192.168.1.246/32 dev eth0

Make sure to add the extra addresses with /32 i.e. without a subnet, as the primary IP address already has a subnet.

Now incoming connections to any of those IP addresses will be handled by your system; all are basically equivalent. Depending on your needs you could e.g. bind specific virtual hosts in apache to a specific IP address. Check the documentation for the given service how to do this.

Outgoing addresses will use the first address by default, unless you specifically configure that a specific IP address should be bound to when making outgoing connections. As you give no details on what you do with your server I can't give more information. Using the addresses as proxies depends on the tool you want to use, although this should also be possible with just one IP address so I don't understand what you specifically mean.