[CentOS-docs] wiki : https://wiki.centos.org/FAQ/CentOS7 : FAQ 4.: "hand-edit the configuration files" ethX alias replacement

Fri Mar 18 10:36:16 UTC 2016
Håvard Sørli <havard at anix.no>

wiki name: HavardSorli
Page for update : https://wiki.centos.org/FAQ/CentOS7

some notes / comments / open points to:

FAQ "4. .... want it to work and to hand-edit the configuration files."

My user case:
"Adding an extra ip to the same interface" in the "old days" an alias.

( I am not sure if this should be an extra faq question, or incorporated 
in FAQ 4)

I have used some time on this matter, and there are lot of suggestions, 
and probably also half way correct but misleading information.

One direction is to disable NetworkManager and make aliases the old way 
(copy the ifcfg-ethX file to ifcfg-ethX:X and do some changes). I got it 
to work, but only with "ifup ethX:X". I did´t get ethX:X to start during 
boot. I stopped testing it, and got back to use nmtui.

The other direction in in a non-graphical environment is to use 
NetworkManager with nmtui. Adding the extra ip on the same interface 
with nmtui, does the trick. I does not show up with ifconfig... but with 
the "new" "ip addr"

What happens in the config file when you use nmtui and add an extra ip:
( extract from /etc/sysconfig/network-scripts/ifcfg-eth0 )

Note the extra IPADDR1 and PREFIX1

Tested on Centos 7.2

I did not test if the extra the extra IPADDR1 and PREFIX1 would fix the 
"load on boot problem" without NetworkManager, but maybe some others 
have some input on that matter.

I think some pros / cons information on this matter would have been nice 
for new readers. It will then be easier to make a choice based on 
knowledge, not assumptions.

Disable og not disable NetworkManager : What do you lose? (main points)
  - integration with the firewalld package <add more info>
  - <add more info>

It my be worth to mention the package NetworkManager-tui and the nmtui 
tool as an alternative to nm-connection-editor and nm-applet in a 
non-graphical environment.

Havard Sorli