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Barracuda CloudGen Firewall

Example - Client-to-Site IKEv1 IPsec VPN with Client Certificate Authentication

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Use a client-to-site VPN to let mobile workers connect securely to your CloudGen Firewall. Each client must have a valid client certificate as well as the username and password to authenticate. Use CudaLaunch on iOS and Android to fully manage the VPN configuration remotely through the SSL VPN templates. To manually configure the native IPsec clients on iOS and Android, verify that you are using encryption settings compatible with the version of your mobile operating system. By default, each user can have only one concurrent client-to-site VPN connection. An Advanced Remote Access subscription is required to enable multiple concurrent client-to-site VPN sessions by the same user. You can connect from any IPv4 or IPv6 address, as long as an external IPv4 and IPv6 address are configured as a service IP address for the VPN service. Traffic passing through the client-to-site VPN is limited to IPv4.


Supported VPN Clients

Although any standard-compliant IPsec client should be able to connect via IPsec, Barracuda Networks recommends using the following clients:

Before You Begin

  • Configure an external or local authentication service. For more information, see Authentication.
  • Identify the subnet (static route) or a range in a local network (proxy ARP) to be used for the VPN clients.

Step 1. Configure the VPN Service Listeners

Configure the IPv4 and IPv6 listener addresses for the VPN service.

  1. From the Service Availability list, select the source for the IPv4 listeners of the VPN service.

    • When selecting Explicit, click + for each IP address and enter the IPv4 addresses in the Explicit Service IPs list.

  2. Click +  to add an entry to the Explicit IPv6 Service IPs.
  3. Select an IPv6 listener from the list of configured explicit IPv6 service IP addresses.

Step 2. Create the VPN Client Network

All VPN clients will receive an IP address from the VPN client network with a static gateway. You can choose the gateway IP address freely from the subnet.

  1. Go to CONFIGURATION > Configuration Tree > Box > Assigned Services > VPN-Service > VPN Settings.
  2. Click Lock.
  3. Verify that the Default Server Certificate and Private key are both valid (green). If the Default Server Certificate and Private key are not valid, see How to Set Up Barracuda VPN CA VPN Certificates.
  4. Configure the client network.
    1. In the left menu, select Client Networks.
    2. Right-click the table and select New Client Network. The Client Network window opens.
    3. In the Client Network window, configure the following settings:
      • Name – Enter a descriptive name for the network. 

      • Type – Select routed (Static Route) . VPN clients are assigned an address via DHCP (fixed or dynamic) in a separate network reserved for the VPN. A static route on the firewall leads to the local network.
      • Network Address – Enter the base network address for the VPN clients.

      • Gateway – Enter the gateway network address.

  5. Click OK.
  6. Click Send Changes and Activate.

Step 3. Configure VPN Group Match Settings

  1. Go to CONFIGURATION > Configuration Tree > Box > Assigned Services > VPN-Service > Client to Site.
  2. Click Lock.
  3. Click the External CA tab.
  4. Click the Click here for options link. The Group VPN Settings window opens.
  5. In the Group VPN Settings window, configure the following settings:
    1. In the X509 Client Security section, select the External Authentication check box.
    2. Select the Authentication Scheme:
      • Default Authentication Scheme – The default authentication scheme is used for all VPN group policies.
      • Extract from username – The authentication scheme is appended to the username. The authentication scheme with the appended name is used with the default authentication scheme acting as a fallback if the authentication scheme name is not present on the firewall. E.g., user1@msad1 or
    3. Select the Default Authentication Scheme from the drop-down list. This authentication scheme must be configured on box level of the firewall.
  6. Click OK.
  7. Click Send Changes and Activate.

Step 4. Create a VPN Group Policy

The VPN group policy specifies the network IPsec settings. You can group patterns to require users to meet certain criteria, as provided by the group membership of the external authentication server (e.g., CN=vpnusers*). You can also define conditions to be met by the certificate (e.g., O(Organization) must be the company name).

  1. Go to CONFIGURATION > Configuration Tree > Box > Assigned Services > VPN-Service > Client to Site.
  2. Click Lock.
  3. Click the External CA tab, and then click the Group Policy tab.
  4. Right-click the table and select New Group Policy. The Edit Group Policy window opens.
  5. Enter a name for the Group Policy.

  6. From the Network list, select the VPN client network.
  7. In the Network Routes table, enter the network that must be reachable through the VPN connection. For example,

    To route all traffic through the client-to-site VPN tunnel, add a network route.


  8. Configure the group policy.
    1. Right-click the Group Policy Condition table and select New Rule. The Group Policy Condition window opens.
    2. In the Group Pattern field, define the groups that will be assigned the policy. E.g., CN=vpnusers*
    3. In the Peer Condition section, verify that IPsec Client check box is selected.

    4. In the X509 Certificate Conditions section, enter matching conditions for the X.509 client certificates.
  9. Click OK.
  10. Configure the encryption and hashing settings:
    1. Click the IPSec IKEv1 tab.
    2. Clear the check box in the top-right corner.
    3. From the IPsec Phase II - Settings list, select the entry that includes (Create New) in its name. For example, if you choose Group Policy as a name, the entry name is Group Policy (Create new)
    4. Set the following encryption algorithm settings for Phase II:
      • Encryption – Select AES.
      • Hash Meth. – Select SHA256.
      • DH-Group – Select None.

      • Time – Enter 3600
      • Minimum – Enter 1200
      • Maximum – Enter 28800
    5. Click Edit IPsec Phase I and select the encryption algorithm in the For XAuth Authentication section:
      • Encryption – Select AES.
      • Hash Meth. – Select SHA . 
      • DH-Group – Select Group2.

      • Time – Enter 3600
      • Minimum – Enter 1200
      • Maximum – Enter 86400
    6. Click OK .
  11. Click Send Changes and then click Activate.

Step 5. Add Access Rules

Add an access rule to connect your client-to-site VPN to your network. For more information, see How to Configure an Access Rule for a Client-to-Site VPN.

Monitoring VPN Connections

On the VPN > Client-to-Site page, you can monitor VPN connections.


The page lists all available client-to-site VPN tunnels. In the Tunnel column, the color of the square indicates the status of the VPN:

  • Blue – The client is currently connected.
  • Green  The VPN tunnel is available, but currently not in use. 
  • Grey – The VPN tunnel is currently disabled. To enable the tunnel, right-click it and select Enable Tunnel.

For more information about the VPN > Client-to-Site page, see VPN Tab.


To troubleshoot VPN connections, see the /VPN/VPN and /VPN/ike log files. For more information, see LOGS Tab.

Next Steps

Configure the remote access clients to connect to the client-to-site VPN.

For more information, see Remote Access Clients.