virtual ips on same server

kitek · 07-20-2011, 10:40 PM

I have some webserver that does virtual name servers for sites. I amd having a second ISP put in tomorrow. How do I have one interface and give it two public IP's? I will use two A records on DNS so it will use either A record to find the host.

Nominal Animal · 07-21-2011, 01:21 AM

You create an alias of the network interface, and assign the IP to the alias.

If the interface you want to alias is for example eth0 then the first alias will be eth0:0. If you add a third IP, you add a second alias, eth0:1, and so on.

The way you do this varies a bit between Linux distributions. You can use a tool like NetworkManager to manage them. On a server, I prefer not to. In RHEL, CentOS, and other RHEL or Fedora variants I would just create /etc/sysconfig/network-scripts/ifup-eth0:0

Code:

DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=IP-address
NETMASK=IP-netmask

In Debian and Ubuntu and variants, I would add the following to /etc/network/interfaces

Code:

auto eth0:0
iface eth0:0 inet static
    address IP-address
    netmask IP-netmask

Above, IP-address and IP-netmask could be for example 10.9.8.4 and 255.255.255.0, respectively.

To activate the new interfaces, I would run sudo /etc/init.d/networking restart (which should work in all). Then I'd also need to restart each service (like Apache) that is supposed to use the new IP address.

kitek · 07-22-2011, 11:43 PM

I have the new ISP in now. I have created a new Virtual Interface as eth0:1 and put the new ip in there as static and the system can ping itself with it. But I am unable to access it out side the box.(internet)

Dani1973 · 07-23-2011, 08:51 AM

What is the exact setup?
Does each ISP caonnection have a router and you use private IPs for your server (192.168.x.x or 172.16-31.x.x or 10.x.x.x)?

Anyway, your server will have 2 different gateways and you cannot configure 2 default gateways (at least not using a basic network configuration).

However, there is a way to do this using iproute2. What you need is a condition like "what comes in on one adapter goes out on that same adapter"

Have a look at this : http://www.linuxquestions.org/questi...teways-145635/

kitek · 07-23-2011, 07:02 PM

Quote:

Originally Posted by Dani1973

What is the exact setup?
Does each ISP caonnection have a router and you use private IPs for your server (192.168.x.x or 172.16-31.x.x or 10.x.x.x)?

Anyway, your server will have 2 different gateways and you cannot configure 2 default gateways (at least not using a basic network configuration).

However, there is a way to do this using iproute2. What you need is a condition like "what comes in on one adapter goes out on that same adapter"

Have a look at this : http://www.linuxquestions.org/questi...teways-145635/

I am going to look at your link after I post. What I have is one ISP with 16 IPS w/router/gateway. Then I just had another put in with another ISP router/gateway.

One has a subnet of 240 and another of 248. I was hoping to have 1 line from each router feed a 10/100 switch. Then on the CentOS box assign one static on eth0 and then another as eth0:0 for the second ISP and then add 2 A records for the 2 IPS to the host. This way if either ISP goes out, the host is still there.

What can you help me with? Pls!