[CentOS] Virtual IP

[Jonathan Billings]

On Thu, Jul 06, 2017 at 11:17:12AM +0300, Amine Tengilimoglu wrote:
>    i need your helps on setting the virtual ip. I am trying to setup static
> virtual ip on CenOS7.  but I want my VIP to should not open when rebooting.

It looks like you're trying to add the second IP on an aliased
interface, something that you used to have to do in older releases of
CentOS.

In C7, you just add multiple IPs to the interface, no need to use
eth0:1 style names.

In the ifcfg-<device>, you can just put in IPADDR1=1.2.3.4 and
NETMASK1=255.255.255.0, and PREFIX1=1.2.3.0.

The documentation is in
/usr/share/doc/initscripts-9.49.37/sysconfig.txt (part of the
initscripts package), which says:


  Base items:
    NAME=<friendly name for users to see>
      Most important for PPP.  Only used in front ends.
    DEVICE=<name of physical device (except dynamically-allocated PPP
      devices where it is the "logical name")>
    IPADDRn=
    PREFIXn=
      Network prefix.  It is used for all configurations except aliases
      and ippp devices.  It takes precedence over NETMASK when both
      PREFIX and NETMASK are set.
    NETMASKn=
      Subnet mask; just useful for aliases and ippp devices.  For all other
      configurations, use PREFIX instead.

    The "n" is expected to be consecutive positive integers starting from 0.
    It can be omitted if there is only one address being configured.

So, you can have IPADDR0, IPADDR1, IPADDR2, etc.

All of these will configure an IP on the device named in the DEVICE
line.  No need to have multiple alias interfaces.

-- 
Jonathan Billings <billings at negate.org>