Managing your cloud resources with OpenStack: Difference between revisions

Security groups allow you to control network traffic into and out of your virtual machines. To manage security groups go to ''Project->Compute->Access & Security'' and select the ''Security Groups'' tab. You will see a list of currently defined security groups. If you have not previously defined any security groups, there will be single ''default'' security group.  

To add or remove security rules from a security group click ''Manage Rules'' for that particular security group. To add a new rule click ''Add Rule'' button in the top right, to remove a rule click ''Delete Rule'' beside the rule you wish to delete.

The ''default'' security group contains a number of rules by default. These rules allow network traffic for any port, from any ip, into (Ingress) a VM originating from another VM in the ''default'' security group for internet protocols version 4 and 6. They also allow network traffic out (Egress) of a VM from any port to any IP for both internet protocol versions. In other words these rules allow a VM which belongs to the ''Default'' security group access out to the internet, to download content (e.g. operating system upgrades, package installations) but does not allow another machine outside the ''default'' security group access to the VM. These default rules allow you to correctly launch a VM, removing them may cause problems when creating new VMs and is not recommended. These rules do not allow access to your VM from outside the default security group which is why to connect to your VM via SSH a security rule was added for port 22 to allow incoming (Ingress) traffic so that you were able to connect to your VM (see [[Cloud Quick Start#Firewall, add rules to allow SSH| Firewall, add rules to allow SSH]]).

You can define multiple security groups and a VM can belong to multiple security groups with each security group having a number of security rules. When deciding on how to manage your security groups and rules, think carefully about what needs to be accessed and who needs to access it. For example, if you will always be connecting to your VM from the same computer with a static IP via SSH it makes sense to allow SSH access only from that IP. To specify the allowed IP or IP range use the [https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing CIDR] box. Further, if you are only connecting to one VM via ssh from the outside, and then connecting to other VMs within the default security group from that VM it makes sense to add the SSH security rule to a separate group and add that group to the VM you are SSHing to, however, you will also need to ensure your ssh keys are configured correctly to ssh between VMs (see [[Ssh keys | SSH Keys]]).

The security group a VM belongs to can be configured when they are created on the ''Launch Instance'' screen under the ''Access & Security'' tab, or after the VM has been launched by selecting ''Edit Security Groups'' form the drop down menu of actions for the VM on the ''Project->Compute->Instances'' page.