How to properly create file for firewall network-interface in CentOS 7.1?

@ktretyak

Was your Droplet setup with or without Private Networking? I ask as eth1 would only be setup if you checked the Private Networking option when setting up your Droplet. This would be a non-public IP and would start with 10.x.x.x.

You can verify this by visiting: https://cloud.digitalocean.com/droplets/

Simply click on Settings on the navigation menu. Under the Navigation tab you’ll see Public Network, Private Network and Public IPv6 Network.

If you see:

To enable private networking please power off your Droplet from the command line.

… under the Private Network heading, then you won’t have an eth1 configuration file (nor will you need to configure it).

By creating a copy of your eth0 file, you’ll actually do more harm than good (in terms of network connectivity) as you’re essentially telling the startup script to source the same IP as two interfaces (which isn’t possible).

–

The standard ifcfg-eth0 file on a Droplet with Private Networking should look something like:

DEVICE='eth0'
TYPE=Ethernet
BOOTPROTO=none
ONBOOT='yes'
HWADDR=04:01:87:32:4b:01
IPADDR=104.236.77.29
NETMASK=255.255.192.0
GATEWAY=104.236.64.1
NM_CONTROLLED='yes'
IPADDR2=10.17.0.20
PREFIX2=16
DNS1=8.8.8.8
DNS2=8.8.4.4

This is from a freshly deployed CentOS 7.x Droplet.

The standard ifcfg-eth1 file on a Droplet with Private Networking should look something like:

DEVICE='eth1'
TYPE=Ethernet
BOOTPROTO=none
ONBOOT='yes'
HWADDR=04:01:87:32:4b:02
IPADDR=10.132.107.203
NETMASK=255.255.0.0
DEFROUTE='no'
NM_CONTROLLED='yes'

(which is from the same droplet)

The differences, of course, will be the HWADDR address, so don’t copy and paste this verbatim.

–

If private networking is not enabled for your Droplet, when you browse to:

/etc/sysconfig/network-scripts/

… what you should see when running ls -al is:

-rw-r--r--. 1 root root   221 Nov 18 04:09 ifcfg-eth0
-rw-r--r--  1 root root   254 Jan 15  2015 ifcfg-lo
...
...
...

If private networking is enabled, what you should see is:

-rw-r--r--. 1 root root   221 Nov 18 04:09 ifcfg-eth0
-rw-r--r--  1 root root   157 Nov 18 04:09 ifcfg-eth1
-rw-r--r--  1 root root   254 Jan 15  2015 ifcfg-lo
...
...
...

Keep in mind, since you just created the eth1 file, you’re going to see it listed. If you had to create it, private networking most likely is not enabled and you don’t need that file.

The tutorials are meant more so as a guide and following them verbatim to the point of creating files not specifically instructed to can present some issues :-) (this being one instance). If you don’t have a file that is shown in a tutorial, don’t sweat it and ask here in the community! I’m always happy to help if I can lend a hand and if I can keep you online while answering questions you may have, then I’ve done my good deed for the day :-).

–

If you can login by console from the DigitalOcean control panel, you should be able to run:

ifconfig eth1 down

… to shutdown the interface. You should then delete the eth1 file.