IPtables NAT/Masquerade to allow OpenStack instances to access sites external to the laptop they're running on - openstack

Question

I have OpenStack running on a Fedora laptop. Openstack hates network interfaces that are managed by NetworkManager, so I set up a dummy interface that's used as the port for the br-ex interface that OpenStack allows instances to communicate through to the outside world. I can connect to the floating ips fine, but they can't get past the subnet that br-ex has. I'd like them to be to reach addresses external to the laptop. I suspect some iptables nat/masquerading magic is required. Does anyone have any ideas?

Answer 1

For Centos7 OpenStack with 3 nodes you should use networking:
just install net-tools and disable NetworkManager:
yum install net-tools -y;
systemctl disable NetworkManager.service
systemctl stop NetworkManager.service
chkconfig network on
Also You need IP tables no firewalld.
yum install -y iptables-services
systemctl enable iptables.service
systemctl disable firewalld.service
systemctl stop firewalld.service
For controller node have one NIC
For Network and compute nodes have 2 NICs
Edit interfaces on all nodes:
for Network eth0: ip:X.X.X.X (external) eth1:10.0.0.1 - no gateway
for Controller node eth0: ip:10.0.0.2 - gateway 10.0.0.1
for compute node eth0: ip:10.0.0.3 - gateway 10.0.0.1
Set up iptables like:
iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A INPUT -i lo -j ACCEPT
iptables -A POSTROUTING -o eth0-j MASQUERADE
iptables -A FORWARD -i eth1 -o eth0-j ACCEPT
iptables -A FORWARD -i eth0-o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT
service iptables save
Also enable forwarding. In file: /etc/sysctkl.conf add line:
net.ipv4.ip_forward = 1
And execute command:
sysctl –p
Should work.