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1. Objectives
In SDN solutions, some networking services are provided by the SDN itself, for example
- Source NAT
- Static NAT
- Load Balancer
- Port forwarding
- Network ACL (VPC)
- Firewall rules (Isolated network)
...
- Dhcp (supported by some SDN providers)
- Dns (supported by some SDN providers)
- UserData (it is unsupported Not supported by SDN providers)
- Vpn (S2S and user)
In this case, the CloudStack VR is used for to provide Dhcp/, Dns /and Userdata services to the vm instances. It is not in the path of the traffic, it acts VM instances, while remaining out of the data path, acting as a helper vmVM

The goal of this feature is to support VPNs in Cloudstack VRto support VPN access from the Cloudstack VR when its out of the data path, thus supporting:
- Remote access VPN for SDN networks
- Site-to-Site VPN for SDN networks
Please note, this supports VPC only. Isolated networks is not supported
2. High Level Design
As the first stepa pre-requisite, the CloudStack VR needs to be provided with a public IP (via static natStatic NAT).
For Remote access vpn, the diagram is as below
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For Site-to-Site VPN, the diagram is as below

In both cases, as the last step, static routes need to be create injected by cloudstack and configured in SDNCloudStack in the SND fabric.
3. Implementation
This described some details of the implementation
3.1 database change
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- has been added to the table
user_ip_address for public ip address, which
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- used for 1:1 NAT to the VPC VR.
`for_router` tinyint(1) DEFAULT '0' COMMENT 'True if the ip address is used by Domain Router to expose services',
- A new column has been added to the table
static_routes , which saves the next hop of static routes.
`next_hop`varchar(50) COMMENT "next hop of the static route" AFTER `vpc_gateway_id`
3.2 ipsec configuration for Remote access VPN
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To create a VPC, please refer to https://docs.cloudstack.apache.org/en/4.19.1.0/adminguide/networking_and_traffic.html#configuring-a-virtual-private-cloud
4.1 Remote Access VPN
Remote In SDN networks, remote access VPN is not supported by on the Source NAT for SDN networksIP.
(1) acquire a Public IP

Please use an IP address which is not in the subnet of Source NAT of VPC VR (not Netris)VPN fabric.
(2) Enable Remote Access VPN
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Please refer to https://docs.cloudstack.apache.org/en/4.19.1.0/adminguide/networking/using_remote_access.html#microsoft-windows-8
Remember Reminder, For for Windows clients,
Allow these protocols → Enable MSCHAP-v2
- Update the registry to support L2TP server behind NAT.
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If remote access VPN is enabled, it gets the the same IP
Image Removed
Otherwise, public IP is used, otherwise CloudStack automatically assign assigns a Public IP.
Image Added
(2) Create customer gateway
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(3) Create VPN connection

5. Test plan
Before testing
- Create VPC offering
- Create Network offering
- Add Vpn Users
5.1 Create VPC, VPC tier and VM
Test cases | Check items and expected results |
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Create VPC, VPC tier and VM |
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Create VPC
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Create VPC tier-1
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Create VM-1 in VPC tier-1
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5.2 Setup Remote Access VPN
Setup Remote Access VPN |
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Setup VPN on the Source NAT IP (IP-0)
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acquire a Public IP (IP-1)
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Enable remote access VPN (IP-1)
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Test VPN in Windows client (with PSK-1)
| Should work from VPN client to VM from VM to VPN client
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Disable Static NAT (IP-1)
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Release IP (IP-1)
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Disable remote access VPN on (IP-1)
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Enable remote access VPN (IP-1) again
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Test VPN in Windows client (with PSK-2)
| Should work from VPN client to VM from VM to VPN client
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Acquire Public IP (IP-2) and Enable VPN
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Disable remote access VPN on (IP-1)
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Disable Static NAT (IP-1)
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Acquire Public IP (IP-3) and Enable VPN
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Test VPN in Windows client (with PSK-3)
| Should work from VPN client to VM from VM to VPN client
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Disable remote access VPN on (IP-3)
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Disable Static NAT (IP-3)
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5.3 Setup Site-to-Site VPN
Setup Site-to-Site VPN |
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Create VPN gateway
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(Optional) If there is no VPN server to test Create another VPC Create VPC tier and VPC VM Create VPN gateway Create VPN customer gateway (in step 1) Create VPN connection
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Create VPN customer gateway (in step 2)
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Create VPN connection
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Check state of VPN connection
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Reset VPN connection (in VR of VPC in step 2) ipsec down vpn-xxxxxx ipsec up vpn-xxxxxx
| VPN connection is Established ping/ssh work from remote to local tier-1 ping/ssh work from local tier-1 to remote
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Reset VPN connection (in VR of VPC in step 1) ipsec down vpn-xxxxxx ipsec up vpn-xxxxxx
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Delete VPN connection
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Disable Static NAT
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Release IP
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Delete VPN gateway
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Disable Static NAT (IP-4)
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5.4 Setup both Remote Access VPN and S2S VPN
Setup both Remote Access VPN and S2S VPN |
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Acquire IP and Enable Remote Access VPN
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Create VPN gateway
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Create VPN connection
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Test VPN in Windows client (with PSK-4)
| Should work from VPN client to VM from VM to VPN client
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Test Site-to-Site VPN connection
| If not Established Should work from remote to tier-1 from tier-1 to remote
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Remove Site-to-Site VPN connection
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Disable Remote Access VPN
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Delete VPN gateway
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Create VPN gateway
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Create VPN connection
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Enable Remote Access VPN
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Test Site-to-Site VPN connection
| If not Established Should work from remote to tier-1 from tier-1 to remote
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Test VPN in Windows client (with PSK-4)
| Should work from VPN client to VM from VM to VPN client
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5.5 Test VPC tier creation
Test VPC tier creation |
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Create VPC tier-2
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Create VM-2 in VPC tier-2
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Test Remote access VPN client to tier-2
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Test Site-to-Site VPN to tier-2
| Should work from remote to tier-2 from tier-2 to remote
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Create VPC tier-3
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Create VM-3 in VPC tier-3
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Test Remote access VPN client to tier-3
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Test Site-to-Site VPN to tier-3
| Should work from remote to tier-3 from tier-3 to remote
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5.6 Test VPC tier deletion (first tier)
Test VPC tier deletion (first tier) |
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Expunge VM-1
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Remove VPC tier-1
| Should succeed Backend Disable static NAT to guest NIC/IP of tier-1 Enable static NAT to guest NIC/IP of tier-2 Update Static routes for multiple CIDRs (next hop: guest IP of VR of tier-2)
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Check VPC VR
| VPC VR: use guest NIC of tier-2 as default route l2tp.conf uses the guest IP of tier-2 vpn-xxxxxx uses the guest IP of tier-2
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Test Remote access VPN client to tier-2 and tier-3
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Test Site-to-Site VPN to tier-2 and tier-3
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5.7 Test VPC VR reboot
Test VPC VR reboot |
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Reboot router
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Check VPC VR
| VPC VR: use guest NIC of tier-2 as default route l2tp.conf uses the guest IP of tier-2 vpn-xxxxxx uses the guest IP of tier-2
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Test Remote access VPN client to tier-2 and tier-3
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Test Site-to-Site VPN to tier-2 and tier-3
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5.8 Test VPC restart with cleanup
Test VPC restart with cleanup |
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Restart VPN with cleanup
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Check VPC VR
| VPC VR: use guest NIC of tier-2 as default route l2tp.conf uses the guest IP of tier-2 vpn-xxxxxx uses the guest IP of tier-2
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Test Remote access VPN client to tier-2 and tier-3
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Test Site-to-Site VPN to tier-2 and tier-3
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5.9 Test VPC tier deletion (from last tier)
Test VPC tier deletion (from last tier) |
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Expunge VM-3
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Remove VPC tier-3
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Expunge VM-2
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Remove VPC tier-2
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Remove VPC
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