[CentOS] How to do virtual IP on NetworkManager

Mon Jan 18 17:50:37 UTC 2021
Simon Matter <simon.matter at invoca.ch>

> On Mon, Jan 18, 2021 at 2:56 PM Jerry Geis <jerry.geis at gmail.com> wrote:
>> Hi All,
>> I use virtual IP from time to time on CentOS 7. just take something like
>> eth0 and make eth0:1 put in there the IP and subnet and bring up the new
>> IP
>> and it works.
>> How do I do that with NetworkManager on the command line (assuming all
>> static IP information)
>> I do something like this from nmcli to set the static address:
>> nmcli connection modify eth0 ipv4.method manual ipv6.method ignore
>> autoconnect yes ipv4.addr gw4 ipv4.dns
>> How then do I add a virtual IP?
>> Thanks
>> Jerry
> With nmcli you should use:
> nmcli con mod eth0 +ipv4.addresses 192.168.1.X/24
> This would modify your existing ifcfg-eth0 adding the lines:
> IPADDR1=192.168.1.X
> PREFIX1=24
> To have the new setting applied and your new ip alias up and running you
> can then use
> nmcli dev reapply eth0
> (supposing the device name bound to the connection is eth0)
> You can also manually modify the file adding the two lines above and then
> run:
> nmcli con reload
> nmcli dev reapply eth0
> I think you should not lose your connection, but always test on a non
> production machine with the same os version... just for safety
> HIH,
> Gianluca

Hi Gianluca,

Am I right that what you describe doesn't add an alias device like eth0:1
but adds the additional IP address to the eth0 device?

Apart from that, when running with NetworkManager, can one still add a
temporary eth0:1 alias (with ifconfig/ip), use it and remove it again, or
does NM somehow prevent this?