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subcollection copyright lastupdated lasttested content-type services account-plan completion-time use-case
solution-tutorials
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2023, 2024
2024-01-05
2023-09-27
tutorial
vpc, virtual-servers
paid
1h
Cybersecurity, VirtualPrivateCloud, VirtualMachines

{{site.data.keyword.attribute-definition-list}}

Connect a VPC landing zone to a network by using a site-to-site VPN

{: #connect-landingzone-site-vpn} {: toc-content-type="tutorial"} {: toc-services="vpc, virtual-servers"} {: toc-completion-time="1h"}

In this tutorial, you use {{site.data.keyword.cloud_notm}} {{site.data.keyword.vpn_vpc_short}} to connect your VPC landing zone deployable architectures securely to an on-premises network through a site-to-site VPN tunnel. You configure a strongSwan VPN gateway to connect to {{site.data.keyword.vpn_vpc_short}}. {: shortdesc}

strongSwan is an open source IPsec-based VPN solution. For more information about strongSwan, see Introduction to strongSwan{: external}.

Objectives

{: #solution-connect-site-vpn-objectives}

You deployed one of the {{site.data.keyword.cloud_notm}} landing zone deployable architectures, like Red Hat OpenShift Container Platform on VPC landing zone{: external}, VPC landing zone{: external} or VSI on VPC landing zone{: external}. The virtual servers are created and working correctly.

By default, network access to the VPC landing zone topology is locked down for security compliance reasons, so you can't access the management or workload VSIs. How can you deploy your application in the workload VSIs that are located in the workload VPC?

The answer is by assigning operator access through the Management VPC. You have several options to give operator access, with varying levels of security, compliance, and ease of enablement.

Architecture diagram of site-to-site-VPN connection with strongSwan{: caption="Figure 1. VPC landing zone connected to a network with a site-to-site VPN and strongSwan" caption-side="bottom"}

In this tutorial, we can learn on how to set up a site-to-site VPN connection to your on-premises network.

Before you begin

{: #solution-connect-site-vpn-prereqs}

  • Deploy an instance of a VPC landing zone deployable architecture. For more information, see Deploying a landing zone deployable architecture.
  • Create a VSI with any Linux-based OS in different Virtual Private Cloud(VPC), subnet, with default ACL rules, and a security group that allows SSH access. Make sure that the VSI is assigned a floating IP, which is used for SSH access to the machine. To simulate an on-premises network, these steps assume that a VSI is deployed onto a separate VPC.

The tutorial is based on the following assumptions:

  • The operating system is CentOS. For more information about other VPN configurations, see Configuring the on-premises VPN gateway.
  • The VPN gateway is deployed on a landing zone VPC that is named management-vpc.
  • Your deployable architecture includes a VSI in management-vpc that is supported by the VSI on VPC landing zone deployable architecture in the {{site.data.keyword.cloud_notm}} catalog.

Set up Strongswan

{: #strongswan-setup} {: step}

For more information about how to install strongSwan on an operating system other than CentOS, see the installation documentation.{: external} {: tip}

  1. Enable IP forwarding:

    1. Open the /etc/sysctl.conf file in a text editor and add the following line:

      net.ipv4.ip_forward = 1

      {: codeblock}

    2. Save and close the file.

    3. Apply the changes with the following command:

      sudo sysctl -p

      {: pre}

  2. Install strongSwan:

    sudo dnf install epel-release -y

    {: pre}

    sudo dnf install strongswan -y

    {: pre}

  3. Start the strongSwan service and enable it to start at system startup:

    systemctl start strongswan

    {: pre}

    systemctl enable strongswan

    {: pre}

    systemctl status strongswan

    {: pre}

  4. Configure security gateways:

    1. Open the /etc/strongswan/ipsec.conf file:

      In the following example, a connection is defined between the on-premises subnet 10.160.x.x/26 with the IP address 169.45.x.x for the strongSwan VPN gateway and the deployable architecture VPN gateway and management VSI subnets 10.10.30.0/24,10.20.10.0/24 with a {{site.data.keyword.vpn_vpc_short}} gateway IP address 169.61.x.x.

       conn all
     type=tunnel
     auto=start
     esp=aes256-sha256!
     ike=aes256-sha256-modp2048!
     left=%any
     leftsubnet=10.160.x.x/26                    #<== c. Subnet CIDR of your on-premises network
     rightsubnet=10.10.30.0/24,10.20.10.0/24     #<== d, e. Subnet CIDR of the deployable architecture VPN gateway. Subnet CIDR of the Management VSI
     right=169.61.x.x                            #<== f. Public IP of the VPN gateway
     leftauth=psk
     rightauth=psk
     leftid="169.45.x.x"                         #<== g. Public IP of your strongSwan server
     keyexchange=ikev2
     lifetime=10800s
     ikelifetime=36000s
     dpddelay=30s
     dpdaction=restart
     dpdtimeout=120s

      {: codeblock}

    2. Click the Navigation menu icon Navigation menu icon, and then click VPC Infrastructure > Virtual server instances from the Compute section.

    3. Specify the subnet of your on-premises network:

      1. Select the VSI that has the strongSwan gateway installed.
      2. In the Network Interfaces section, click the subnet name of the interface that has the floating IP assigned to it.
      3. Copy the subnet IP range of your on-premises network to the leftsubnet property in the ipsec.conf file.

    4. Specify the CIDR of the management VSI:

      1. Click Subnets in the Network section to open the Subnets for VPC page.
      2. Search for subnets associated with the management VPC (in our example, management-vpc).
      3. From the list of subnets, click the subnet name with the management VSI deployed.
      4. Copy the subnet IP range column to the rightsubnet property in the ipsec.conf file.

    5. Specify the CIDRs of the landing zone VPN gateway:

      1. Click VPNs in the Network section to open the VPNs for VPC page.

      2. Make sure that the Site-to-site gateways > VPN gateways tabs are selected.

      3. Select the site-to-site VPN associated with your landing zone deployable architecture (in our example, management-gateway).

      4. On the VPN gateway details page, click Subnet to see details about the subnet associated with your VPN gateway.

      5. Copy the subnet IP range column of the deployable architecture VPN gateway.

        Copy the IP range to the beginning of the rightsubnet property in the ipsec.conf file. Separate this range from the CIDR of the management VSI with a comma, as shown in the example.

    6. Specify the public IP address of the VPN gateway:

      1. On the VPNs for VPC page, make sure that the Site-to-site gateways > VPN gateways tabs are selected.
      2. Select the site-to-site VPN associated with your landing zone deployable architecture again (in our example, management-gateway).
      3. In the VPN gateway details page, click any Public IP to copy it and paste it in the right property in the ipsec.conf file.

    7. Verify the public IP of your strongSwan server:

      • Click Virtual server instances in the Compute section.
      • Click the name of the VSI that has the strongSwan gateway installed.
      • Click the Floating IP that is associated with the subnet you chose in the Step 1 in the Network Interfaces section.
      • Paste the IP address in the leftid property to identify the IP address of the strongSwan server.

  5. Configure a pre-shared key (PSK) for peer-to-peer authentication.

    1. On the command line, issue the following command to generate a strong PSK for the peers to use:

      head -c 24 /dev/urandom | base64

      {: pre}

    2. Add the PSK to the /etc/strongswan/ipsec.secrets file.

      # <Public IP of your strongSwan server> <Public IP of the Landing Zone VPN gateway> : PSK "***********"
169.45.x.x  169.61.x.x : PSK "***********"

      {: codeblock}

  6. Start the strongSwan service and check the status of connections.

    systemctl restart strongswan

    {: pre}

    ❯ strongswan status
  Security Associations (0 up, 1 connecting):
        all[1]: CONNECTING, 10.160.x.x[%any]...169.61.x.x[%any]

    {: screen}

    It's normal for the status to show '0 up, 1 connecting' because the connection on the landing zone side is not yet set up.

Edit the ACLs to allow connections from strongSwan

{: #solution-connect-site-vpn-strongswan-acls} {: step}

  1. In the {{site.data.keyword.cloud_notm}} console, click the Navigation menu icon Navigation menu icon, and then click VPC Infrastructure > Access control lists from the Network section.

  2. Select the ACL management-acl that is associated with your landing zone deployable architecture VPC (in our example, management-vpc).

  3. Create inbound rules for the on-premises subnet and public IP to access the VPN subnet.

    1. Click Create in the inbound rules section.

    2. Add two inbound rules with the following values:

      Priority Allow or deny Protocol Source Destination
      1 Allow ALL strongSwan VSI public IP LZ s2s VPN gateway's subnet
      2 Allow ALL strongSwan VSI subnet CIDR LZ VPC CIDR
      3 Allow ALL LZ VPC CIDR strongSwan VSI subnet CIDR
      4 Allow ALL strongSwan VSI public IP Management VSI subnet CIDR
      {: caption="Table 1. Inbound ACL rules" caption-side="bottom"}

  4. Create outbound rules for the VPN subnet and public IP to access the on-premises subnet.

    1. Click Create in the Outbound rules section.

    2. Add two outbound rules with the following values:

      Priority Allow or deny Protocol Source Destination
      1 Allow ALL LZ s2s VPN gateway's subnet strongSwan VSI public IP
      2 Allow ALL LZ VPC CIDR strongSwan VSI subnet CIDR
      3 Allow ALL strongSwan VSI subnet CIDR LZ VPC CIDR
      4 Allow ALL Management VSI subnet CIDR strongSwan VSI public IP
      {: caption="Table 2. Outbound ACL rules" caption-side="bottom"}

Create a VPN connection in the {{site.data.keyword.cloud_notm}} VPN

{: #create-vpn} {: step}

  1. Click the Navigation menu icon Navigation menu icon, and then click VPC Infrastructure > VPN from the Network section.

  2. Select the site-to-site VPN that is associated with your landing zone deployable architecture (in our example, management-gateway).

  3. On the gateway details page, click Create in the VPN connections section.

  4. Define a connection between this gateway and a network outside your VPC by specifying the following information:

    • VPN connection name: Enter a name for the connection, such as my-connection.
    • Peer gateway address: Specify the floating IP address of the strongSwan server.
    • Pre-shared key: Specify the authentication key of the VPN gateway. Make sure that you use the same pre-shared key that is mentioned in the strongSwan secrets.
    1. Create an IKE policy:
      1. From the VPN connection for VPC page, select Create IKE policy.
      2. Specify the following information:
        • Name: Enter a name for the IKE policy.
        • Resource group: Select the resource group for this IKE policy.
        • IKE version: Set the IKE protocol version to 2.
        • Encryption: Encryption algorithm to use for IKE Phase 1. Set Encryption to aes256.
        • Authentication: Authentication algorithm to use for IKE Phase 1. Set Authentication to sha256.
        • Diffie-Hellman group: DH group to use for IKE Phase 1. Set DH group to 14
        • Key lifetime: Lifetime in number of seconds of Phase 1 tunnel. Set Key lifetime to 36000
      3. Click Create.
    2. Create an IPsec policy:
      1. From the VPN connection for VPC page, select Create IPsec policy.
      2. Specify the following information:
        • Name: Enter a name for the IPsec policy.
        • Resource group: Select the resource group for this IPsec policy.
        • Encryption: Encryption algorithm to use for IKE Phase 2. Set Encryption to aes256.
        • Authentication: Authentication algorithm to use for IKE Phase 2. Set Authentication to sha256.
        • Perfect Forward Secrecy: Disable PFS.
        • Diffie-Hellman Group (If PFS is enabled): DH group to use for IKE Phase 2 key exchange. When PFS is disabled, the DH group is set to 14 by default.
        • Key lifetime: Lifetime in number of seconds of the Phase 2 tunnel. Set the lifetime to 10800.
      3. Click Create.

  5. Click Create VPN connection.

Create a route in the UI

{: #strongswan-create-route} {: step}

Follow these steps to create a route to control how the destination network traffic is directed.

  1. Click the Navigation menu icon Navigation menu icon, and then click VPC Infrastructure > Routing tables from the Network section.
  2. Select the management VPC (in our example, management-vpc).
  3. Click the default routing table that is associated with management-vpc.
  4. In the Routes section, click Create.
  5. On the Create route page, specify the following information:

    • Zone: Select the zone on which the VPN gateway is deployed.

    • Name: Type a name for the new route.

      You can create a name by using a combination of random names. {: tip}

    • Destination CIDR: Specify the subnet CIDR of your strongSwan VSI network.

    • Action: Select Deliver when the route destination is in the VPC or if an on-premises private subnet is connected with a VPN gateway.

    • Next hop type: Click VPN connection and select the VPN connection that you created in the previous step.

  6. Click Save.
  7. Similarly, create a separate route for the management VSI zone.
    • Zone: Select the zone on which management VSI is deployed.
    • Name: Type a name for the new route.
    • Destination CIDR: Specify the subnet CIDR of your strongSwan VSI network.
    • Action: Select Deliver when the route destination is in the VPC or if an on-premises private subnet is connected with a VPN gateway.
    • Next hop type: Click VPN connection and select the VPN connection that you created in the previous step.
  8. Click Save.

Check Strongswan Status

{: #strongswan-status} {: step}

After you complete the previous steps, check the status of the strongSwan process in the strongSwan VSI.

  1. Restart the strongSwan service.

    systemctl restart strongswan

    {: pre}

  2. Check the status of connections.

    ❯ strongswan status
  Security Associations (1 up, 0 connecting):
        all[1]: ESTABLISHED 59 minutes ago, 10.160.x.x[169.45.x.x]...169.61.x.x[169.61.x.x]
        all{1}:  INSTALLED, TUNNEL, reqid 1, ESP in UDP SPIs: cfbbd5d9_i c864dc75_o
        all{1}:   10.160.x.x/24 === 10.10.10.0/24 10.20.10.0/24

    {: pre}

Test the site-to-site gateway setup

{: #test-connection} {: step}

Follow these steps to verify that you have a working site-to-site gateway.

  1. Access the strongSwan VSI. On your computer, issue the following command on the command line:

    ssh -i <private-key> root@<Floating IP of strongswan VSI>

    {: pre}

  2. Access the management VSI by completing the following steps:

    1. Go to Virtual server instances for VPC. Copy the private IP (“Reserved IP”) for the VSI that's labeled <management-server-2> (10.20.10.4 in this example).
    2. On the strongSwan VSI, ping the management VSI.
    ❯ ping 10.20.10.4
PING 10.20.10.4 (10.20.10.4) 56(84) bytes of data.
64 bytes from 10.20.10.4: icmp_seq=1 ttl=62 time=99.5 ms
64 bytes from 10.20.10.4: icmp_seq=2 ttl=62 time=99.4 ms
64 bytes from 10.20.10.4: icmp_seq=3 ttl=62 time=99.4 ms
^C
--- 10.20.10.4 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 99.415/99.462/99.502/0.035 ms

    {: pre}

    1. You can also SSH to <management-server-2>. Copy the private key that corresponds to the public key used to deploy the landing zone to the strongSwan VSI and run the following command on the strongSwan command line:
    ssh -i <private-key> [email protected]

    {: pre}

Summary

{: #solution-connect-site-vpn-summary}

After you set up the site-to-site VPN to the management VPC, you can access the workload VPC through the management VSIs with the necessary ACL rules in place. With an established connection to the workload VPC, you can deploy your application on the workload VSIs.

Related content

{: #connect-site-vpn-related}

Tutorial: Connect to a VPC landing zone by using a client-to-site VPN