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Barracuda NextGen Firewall X

This Product is End-of-Life and End-Of-Support

End-Of-Life and End-Of-Support on December 1st, 2020: All Barracuda Firewall X-Series sales will cease; neither new sales nor any renewals will be available. If you currently hold a maintenance and support contract, you will continue to receive our award-winning support and services until your contract expires. Please see the End-Of-Life definition as described in the End of Support and End of Life Information.

How to Configure Apple iOS VPN Client for IPsec VPN with Certificate Authentication

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Because certificates longer than 512-bit do not work for iOS VPN clients with iOS version 6.0, it is recommended that you update to the latest version of iOS.

For client-to-site IPsec VPN connections, you can use Apple iOS devices. Follow the steps in this article to configure Apple iOS devices for IPsec VPN connections with the Barracuda NextGen Firewall X-Series.


Before you Begin

To use Apple iOS devices to connect to a client-to-site IPsec VPN, you must have the following:

  • Apple device with iOS 5.1 or above.
  • How to Configure a Client-to-Site VPN with Certificate Authentication.
  • Root, server, and client certificates that meet the requirements set by Apple.
    The following table shows the required X.509 certificates, their settings, and where they must be installed.

    X.509 Certificate TypeInstallation DeviceFile TypeChain of TrustX.509 Extensions and Values
    Root CertificateBarracuda NextGen Firewall X-Series + Apple iOS DevicePEMTrust Anchor
    • Mandatory option for key usage: Certificate sign; CRL sign.
    Server CertificateBarracuda NextGen Firewall X-SeriesPKCS12End Instance
    • Subject Alternative Name: Only use the DNS tag with a FQDN which resolves to the IP address the VPN Service or a wildcard certificate. Do not use the IP tag. E.g., or DNS:*
    • Key Usage - Including the "Digital Signature" flag.
    Client CertificateApple iOS DevicePKCS12End Instance
    • Key Usage - Including the "Digital Signature" flag.

When creating X.509 certificates:

  • Do not use identical Subject Alternative Names settings. Subject Alternative Names must also not contain the management IP address of the X-Series Firewall.
  • Only use the X.509 extensions that are listed in the table above.
Example iOS Certificate Settings
Root Certificate
StatusSignature Algorithmsha1WithRSAEncryption
SubjectRFC,OU=documentation,O=Barracuda Networks,L=Innsbruck,ST=Tirol,C=AT
ExtensionsX509v3 Basic ConstraintsCA:TRUE
X509v3 Key UsageDigital Signature, Key Agreement, Certificate Sign
Server Certificate
StatusSignature Algorithmsha1WithRSAEncryption
SubjectRFC,OU=docu,O=Barracuda Network AG,L=Innsbruck,ST=Tyrol,C=AT
IssuerRFC,OU=documentation,O=Barracuda Networks,L=Innsbruck,ST=Tirol,C=AT
ExtensionsX509v3 Key UsageDigital Signature, Key Agreement, Certificate Sign
 X509v3 Subject Alternative
Client Certificate
StatusSignature Algorithmsha1WithRSAEncryption
SubjectRFC,OU=documentation,O=Barracuda Networks,L=Innsbruck,ST=Tyrol,C=AT
IssuerRFC,OU=documentation,O=Barracuda Networks,L=Innsbruck,ST=Tirol,C=AT
ExtensionsX509v3 Key UsageDigital Signature

Configure the Apple iOS Device

Import the certificates

You must import the root and the client certificate on the Apple iOS device. You can import the certificate via email or by downloading it from a web server. If you are using a Mobile Device Management (MDM) server, you can also push the certificates to your devices.

Configure the Client-To-Site VPN

To configure an Apple iOS device for IPsec VPN connections with the X-Series Firewall:

  1. On the iOS device, tap Settings > General > VPN > Add VPN Configuration.
  2. On the Add VPN configuration screen, tap the IPsec tab.
  3. Configure the following settings:
    • Server – The Subject Alternative Name used in your certificates.
    • Account and Password – The XAUTH username and password.
    • Use Certificate – Enable this setting.
    • Certificate – The X.509 client certificate.
  4. Tap Save in the top right corner. The VPN configuration then appears on the VPN screen.

Connect to the VPN with the Apple iOS Device

After configuring the Apple device, you can connect to the IPsec VPN.

On your Apple iOS device, tap Settings and then turn on VPN. After a few seconds, the VPN icon appears in the status bar to indicate that the connection is successful.

Establishing VPN through NAT can be problematic. If you experience connection losses, increase the UDP timeout on the NAT'd device. For example, the iPhone sends keepalive packets every 60 seconds, so you can enter any value over 60 seconds.

Unfortunately, many cell phone providers use NAT to connect mobile devices to the internet. Contact your cell phone provider support for help.