AWS Multiple IPs Question

Operating System & Version
CentOS v7.9.2009 STANDARD kvm
cPanel & WHM Version
106.0.11

Volox

Active Member
Jun 11, 2017
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San Diego
cPanel Access Level
Root Administrator
I setup cPanel some time ago on an AWS EC2 instance. At the time the documentation seemed to indicate that the best way to get clean separation of the IPs / domains was to have multiple network interfaces each of which have an elastic IP address that is used for each of the domains that need separation. Overall this approach seems to be working fine with the right level of isolation between the domains.

However I recently noticed that the dhclient is trying to reach out from the non-primary interfaces. I was under the impression at the time I set this up that the best practice was to leave the network configurations set to DHCP. However at this point I can't find any guidance on that and I'm wondering if that is correct.

Does anyone have experience or information on the best practices for DHCP vs. static IP setup on EC2 instances? And if you use static setup, how do you ensure the server is using the appropriate AWS DNS servers?
 

Volox

Active Member
Jun 11, 2017
29
6
53
San Diego
cPanel Access Level
Root Administrator
Hey there! It would be best to reach out to AWS directly about this one, as cPanel doesn't manage the network interfaces since we just read what is configured on the operating system side of things.
I guess I thought cPanel would be of some help here since cPanel is the one that packages the AMI for the marketplace. It also seems like the guidance on setting up the NAT associations in cPanel is something where the guidance comes from cPanel, so could someone at least speak to what would happen if DHCP is running and the private IP changes? From the cPanel perspective would the associations cause things to stop working?
 

cPRex

Jurassic Moderator
Staff member
Oct 19, 2014
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In general, cPanel doesn't expect the private IP to change. If that happened, you'd need to manually rebuild the NAT as well as many configurations on the system, since that gets written to everything on the server - Apache configuration, cPanel userdata, etc.