Managing your cloud resources with OpenStack/en: Difference between revisions

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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]]).
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 more than one security group. 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. Strive to minimize the IP addresses and ports in your Ingress rules. For example, if you will always be connecting to your VM via SSH from the same computer with a static IP 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 only need to connect to one VM via SSH from the outside and then can use that as a gateway to any other Cloud VMs, it makes sense to put the SSH rule in a separate security group and add that group only to the gateway VM. However, you will also need to ensure your SSH keys are configured correctly to allow you to use SSH between VMs (see [[Ssh keys | SSH Keys]]).
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 groups a VM belongs to can be chosen when it is 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.
The security groups a VM belongs to can be chosen when it is 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.
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