# Guide: How to Set Up and Use IKEv2 VPN *Read this in other languages: [English](ikev2-howto.md), [简体中文](ikev2-howto-zh.md).* **Note:** You may also connect using [IPsec/L2TP](clients.md) or [IPsec/XAuth](clients-xauth.md) mode. * [Introduction](#introduction) * [Using helper scripts](#using-helper-scripts) * [Configure IKEv2 VPN clients](#configure-ikev2-vpn-clients) * [Manage client certificates](#manage-client-certificates) * [Manually set up IKEv2 on the VPN server](#manually-set-up-ikev2-on-the-vpn-server) * [Troubleshooting](#troubleshooting) * [Remove IKEv2](#remove-ikev2) * [References](#references) ## Introduction Modern operating systems (such as Windows 7 and newer) support the IKEv2 standard. Internet Key Exchange (IKE or IKEv2) is the protocol used to set up a Security Association (SA) in the IPsec protocol suite. Compared to IKE version 1, IKEv2 contains improvements such as Standard Mobility support through MOBIKE, and improved reliability. Libreswan can authenticate IKEv2 clients on the basis of X.509 Machine Certificates using RSA signatures. This method does not require an IPsec PSK, username or password. It can be used with: - Windows 7, 8.x and 10 - OS X (macOS) - iOS (iPhone/iPad) - Android 4.x and newer (using the strongSwan VPN client) - Linux After following this guide, you will be able to connect to the VPN using IKEv2 in addition to the existing [IPsec/L2TP](clients.md) and [IPsec/XAuth ("Cisco IPsec")](clients-xauth.md) modes. ## Using helper scripts **New:** For macOS and iOS clients, the helper script can now create .mobileconfig files to simplify client setup and improve VPN performance. **Important:** Before continuing, you should have successfully set up your own VPN server, and (optional but recommended) updated Libreswan. **Docker users, see here**. Use this helper script to automatically set up IKEv2 on the VPN server: ``` wget https://git.io/ikev2setup -O ikev2.sh && sudo bash ikev2.sh --auto ``` The script must be run using `bash`, not `sh`. The command above runs the helper script in auto mode, using default options. Remove the `--auto` parameter if you want to customize IKEv2 setup options. When finished, continue to [configure IKEv2 VPN clients](#configure-ikev2-vpn-clients).

You may optionally specify a DNS name and/or custom DNS servers. Click here for details.

When running IKEv2 setup in auto mode, advanced users can optionally specify a DNS name to be used as the VPN server's address. The DNS name must be a fully qualified domain name (FQDN). Example: ``` sudo VPN_DNS_NAME='vpn.example.com' bash ikev2.sh --auto ``` By default, IKEv2 clients are set to use Google Public DNS when the VPN is active. When running IKEv2 setup in auto mode, you may optionally specify custom DNS server(s). Example: ``` sudo VPN_DNS_SRV1=1.1.1.1 VPN_DNS_SRV2=1.0.0.1 bash ikev2.sh --auto ```

Click here to view detailed usage information for the IKEv2 helper script.

``` Usage: bash ikev2.sh [options] Options: --auto run IKEv2 setup in auto mode using default options (for initial IKEv2 setup only) --addclient [client name] add a new IKEv2 client using default options (after IKEv2 setup) --exportclient [client name] export an existing IKEv2 client using default options (after IKEv2 setup) --listclients list the names of existing IKEv2 clients (after IKEv2 setup) --removeikev2 remove IKEv2 and delete all certificates and keys from the IPsec database -h, --help show this help message and exit To customize IKEv2 or client options, run this script without arguments. ```

## Configure IKEv2 VPN clients *Read this in other languages: [English](ikev2-howto.md#configure-ikev2-vpn-clients), [简体中文](ikev2-howto-zh.md#配置-ikev2-vpn-客户端).* **Note:** If you want to generate certificates for additional VPN clients, or export configuration for an existing client, just run the [helper script](#using-helper-scripts) again. Use option `-h` to show detailed usage information. * [Windows 7, 8.x and 10](#windows-7-8x-and-10) * [OS X (macOS)](#os-x-macos) * [iOS (iPhone/iPad)](#ios) * [Android](#android) * [Linux](#linux) ### Windows 7, 8.x and 10 1. Securely transfer the generated `.p12` file to your computer, then import it into the "Computer account" certificate store. To import the `.p12` file, run the following from an elevated command prompt: ```console # Import .p12 file (replace with your own value) certutil -f -importpfx "\path\to\your\file.p12" NoExport ``` Alternatively, you can manually import the `.p12` file. Click here for instructions. Make sure that the client cert is placed in "Personal -> Certificates", and the CA cert is placed in "Trusted Root Certification Authorities -> Certificates". **Note:** Ubuntu 18.04 users may encounter the error "The password you entered is incorrect" when trying to import the `.p12` file. See [Troubleshooting](#troubleshooting). 1. On the Windows computer, add a new IKEv2 VPN connection. For Windows 8.x and 10, it is recommended to create the VPN connection using the following commands from a command prompt, for improved security and performance. Windows 7 does not support these commands, you may manually create the VPN connection (see below). ```console # Create VPN connection (replace server address with your own value) powershell -command "Add-VpnConnection -ServerAddress 'Your VPN Server IP (or DNS name)' -Name 'My IKEv2 VPN' -TunnelType IKEv2 -AuthenticationMethod MachineCertificate -EncryptionLevel Required -PassThru" # Set IPsec configuration powershell -command "Set-VpnConnectionIPsecConfiguration -ConnectionName 'My IKEv2 VPN' -AuthenticationTransformConstants GCMAES128 -CipherTransformConstants GCMAES128 -EncryptionMethod AES256 -IntegrityCheckMethod SHA256 -PfsGroup None -DHGroup Group14 -PassThru -Force" ``` Alternatively, you can manually create the VPN connection. Click here for instructions. If you specified the server's DNS name (instead of its IP address) during IKEv2 setup, you must enter the DNS name in the **Internet address** field. 1. Enable stronger ciphers for IKEv2 with a one-time registry change. This is optional, but recommended. Download and import the `.reg` file below, or run the following from an elevated command prompt. Read more here. - For Windows 7, 8.x and 10 ([download .reg file](https://dl.ls20.com/reg-files/v1/Enable_Stronger_Ciphers_for_IKEv2_on_Windows.reg)) ```console REG ADD HKLM\SYSTEM\CurrentControlSet\Services\RasMan\Parameters /v NegotiateDH2048_AES256 /t REG_DWORD /d 0x1 /f ``` To connect to the VPN: Click on the wireless/network icon in your system tray, select the new VPN entry, and click **Connect**. Once successfully connected, you can verify that your traffic is being routed properly by looking up your IP address on Google. It should say "Your public IP address is `Your VPN Server IP`". If you get an error when trying to connect, see [Troubleshooting](#troubleshooting). ### OS X (macOS) First, securely transfer the generated `.mobileconfig` file to your Mac, then double-click and follow the prompts to import as a macOS profile. When finished, check to make sure "IKEv2 VPN" is listed under System Preferences -> Profiles. To connect to the VPN: 1. Open System Preferences and go to the Network section. 1. Select the VPN connection with `Your VPN Server IP` (or DNS name). 1. Check the **Show VPN status in menu bar** checkbox. 1. Click **Connect**. (Optional feature) You can choose to enable VPN On Demand. This is an "always-on" feature that can automatically connect to the VPN while on Wi-Fi. To enable, check the **Connect on demand** checkbox for the VPN connection, and click **Apply**.

If you manually set up IKEv2 without using the helper script, click here for instructions.

First, securely transfer the generated `.p12` file to your Mac, then double-click to import into the **login** keychain in **Keychain Access**. Next, double-click on the imported `IKEv2 VPN CA` certificate, expand **Trust** and select **Always Trust** from the **IP Security (IPsec)** drop-down menu. Close the dialog using the red "X" on the top-left corner. When prompted, use Touch ID or enter your password and click "Update Settings". When finished, check to make sure both the new client certificate and `IKEv2 VPN CA` are listed under the **Certificates** category of **login** keychain. 1. Open System Preferences and go to the Network section. 1. Click the **+** button in the lower-left corner of the window. 1. Select **VPN** from the **Interface** drop-down menu. 1. Select **IKEv2** from the **VPN Type** drop-down menu. 1. Enter anything you like for the **Service Name**. 1. Click **Create**. 1. Enter `Your VPN Server IP` (or DNS name) for the **Server Address**. **Note:** If you specified the server's DNS name (instead of its IP address) during IKEv2 setup, you must enter the DNS name in the **Server Address** and **Remote ID** fields. 1. Enter `Your VPN Server IP` (or DNS name) for the **Remote ID**. 1. Enter `Your VPN client name` in the **Local ID** field. **Note:** This must match exactly the client name you specified during IKEv2 setup. Same as the first part of your `.p12` filename. 1. Click the **Authentication Settings...** button. 1. Select **None** from the **Authentication Settings** drop-down menu. 1. Select the **Certificate** radio button, then select the new client certificate. 1. Click **OK**. 1. Check the **Show VPN status in menu bar** checkbox. 1. Click **Apply** to save the VPN connection information. 1. Click **Connect**.

If you manually set up IKEv2 without using the helper script, click here for instructions.

First, securely transfer the generated `ikev2vpnca.cer` and `.p12` files to your iOS device, then import them one by one as iOS profiles. To transfer the files, you may use: 1. AirDrop, or 1. Upload to your device using "File Sharing" in iTunes, then open the "Files" app on your iOS device, move the uploaded files to the "On My iPhone" folder. After that, tap each file and go to "Settings" to import, or 1. Host the files on a secure website of yours, then download and import them in Mobile Safari. When finished, check to make sure both the new client certificate and `IKEv2 VPN CA` are listed under Settings -> General -> Profiles. 1. Go to Settings -> General -> VPN. 1. Tap **Add VPN Configuration...**. 1. Tap **Type**. Select **IKEv2** and go back. 1. Tap **Description** and enter anything you like. 1. Tap **Server** and enter `Your VPN Server IP` (or DNS name). **Note:** If you specified the server's DNS name (instead of its IP address) during IKEv2 setup, you must enter the DNS name in the **Server** and **Remote ID** fields. 1. Tap **Remote ID** and enter `Your VPN Server IP` (or DNS name). 1. Enter `Your VPN client name` in the **Local ID** field. **Note:** This must match exactly the client name you specified during IKEv2 setup. Same as the first part of your `.p12` filename. 1. Tap **User Authentication**. Select **None** and go back. 1. Make sure the **Use Certificate** switch is ON. 1. Tap **Certificate**. Select the new client certificate and go back. 1. Tap **Done**. 1. Slide the **VPN** switch ON.

If your device runs Android 6.0 or older, click here for additional instructions.

If your device runs Android 6.0 (Marshmallow) or older, in order to connect using the strongSwan VPN client, you must make the following change on the VPN server: Edit `/etc/ipsec.d/ikev2.conf` on the server. Append `authby=rsa-sha1` to the end of the `conn ikev2-cp` section, indented by two spaces. Save the file and run `service ipsec restart`.

(Optional feature) You can choose to enable the "Always-on VPN" feature on Android. Launch the **Settings** app, go to Network & internet -> Advanced -> VPN, click the gear icon on the right of "strongSwan VPN Client", then enable the **Always-on VPN** and **Block connections without VPN** options.

If you manually set up IKEv2 without using the helper script, click here for instructions.

**Android 10 and newer:** 1. Securely transfer the generated `.p12` file to your Android device. 1. Install strongSwan VPN Client from **Google Play**. 1. Launch the **Settings** application. 1. Go to Security -> Advanced -> Encryption & credentials. 1. Tap **Install certificates from storage (or SD card)**. 1. Choose the `.p12` file you transferred from the VPN server, and follow the prompts. **Note:** To find the `.p12` file, tap the three-line menu button, then browse to the location you saved the file. 1. Launch the strongSwan VPN client and tap **Add VPN Profile**. 1. Enter `Your VPN Server IP` (or DNS name) in the **Server** field. **Note:** If you specified the server's DNS name (instead of its IP address) during IKEv2 setup, you must enter the DNS name in the **Server** field. 1. Select **IKEv2 Certificate** from the **VPN Type** drop-down menu. 1. Tap **Select user certificate**, select the new client certificate and confirm. 1. **(Important)** Tap **Show advanced settings**. Scroll down, find and enable the **Use RSA/PSS signatures** option. 1. Save the new VPN connection, then tap to connect. **Android 4 to 9:** 1. Securely transfer the generated `.p12` file to your Android device. 1. Install strongSwan VPN Client from **Google Play**. 1. Launch the strongSwan VPN client and tap **Add VPN Profile**. 1. Enter `Your VPN Server IP` (or DNS name) in the **Server** field. **Note:** If you specified the server's DNS name (instead of its IP address) during IKEv2 setup, you must enter the DNS name in the **Server** field. 1. Select **IKEv2 Certificate** from the **VPN Type** drop-down menu. 1. Tap **Select user certificate**, then tap **Install certificate**. 1. Choose the `.p12` file you transferred from the VPN server, and follow the prompts. **Note:** To find the `.p12` file, tap the three-line menu button, then browse to the location you saved the file. 1. **(Important)** Tap **Show advanced settings**. Scroll down, find and enable the **Use RSA/PSS signatures** option. 1. Save the new VPN connection, then tap to connect.

Once successfully connected, you can verify that your traffic is being routed properly by looking up your IP address on Google. It should say "Your public IP address is `Your VPN Server IP`". If you get an error when trying to connect, see [Troubleshooting](#troubleshooting). ### Linux Before configuring Linux VPN clients, you must make the following change on the VPN server: Edit `/etc/ipsec.d/ikev2.conf` on the server. Append `authby=rsa-sha1` to the end of the `conn ikev2-cp` section, indented by two spaces. Save the file and run `service ipsec restart`. To configure your Linux computer to connect to IKEv2 as a VPN client, first install the strongSwan plugin for NetworkManager: ```bash # Ubuntu and Debian sudo apt-get update sudo apt-get install network-manager-strongswan # Arch Linux sudo pacman -Syu # upgrade all packages sudo pacman -S networkmanager-strongswan # Fedora sudo yum install NetworkManager-strongswan-gnome # CentOS sudo yum install epel-release sudo yum --enablerepo=epel install NetworkManager-strongswan-gnome ``` Next, securely transfer the generated `.p12` file from the VPN server to your Linux computer. After that, extract the CA certificate, client certificate and private key. Replace `vpnclient.p12` in the example below with the name of your `.p12` file. ```bash # Example: Extract CA certificate, client certificate and private key. # You may delete the .p12 file when finished. # Note: You will need to enter the import password, which can be found # in the output of the IKEv2 helper script. openssl pkcs12 -in vpnclient.p12 -cacerts -nokeys -out ikev2vpnca.cer openssl pkcs12 -in vpnclient.p12 -clcerts -nokeys -out vpnclient.cer openssl pkcs12 -in vpnclient.p12 -nocerts -nodes -out vpnclient.key rm vpnclient.p12 # (Important) Protect certificate and private key files # Note: This step is optional, but strongly recommended. sudo chown root.root ikev2vpnca.cer vpnclient.cer vpnclient.key sudo chmod 600 ikev2vpnca.cer vpnclient.cer vpnclient.key ``` You can then set up and enable the VPN connection: 1. Go to Settings -> Network -> VPN. Click the **+** button. 1. Select **IPsec/IKEv2 (strongswan)**. 1. Enter anything you like in the **Name** field. 1. In the **Gateway (Server)** section, enter `Your VPN Server IP` (or DNS name) for the **Address**. 1. Select the `ikev2vpnca.cer` file for the **Certificate**. 1. In the **Client** section, select **Certificate(/private key)** in the **Authentication** drop-down menu. 1. Select **Certificate/private key** in the **Certificate** drop-down menu (if exists). 1. Select the `vpnclient.cer` file for the **Certificate (file)**. 1. Select the `vpnclient.key` file for the **Private key**. 1. In the **Options** section, check the **Request an inner IP address** checkbox. 1. In the **Cipher proposals (Algorithms)** section, check the **Enable custom proposals** checkbox. 1. Leave the **IKE** field blank. 1. Enter `aes128gcm16` in the **ESP** field. 1. Click **Add** to save the VPN connection information. 1. Turn the **VPN** switch ON. Once successfully connected, you can verify that your traffic is being routed properly by looking up your IP address on Google. It should say "Your public IP address is `Your VPN Server IP`". If you get an error when trying to connect, see [Troubleshooting](#troubleshooting). ## Manage client certificates ### List existing clients If you want to list the names of existing IKEv2 clients, run the [helper script](#using-helper-scripts) with the `--listclients` option. To view detailed usage information for the IKEv2 helper script, see [this section](#using-helper-scripts). ### Add a client certificate To generate certificates for additional IKEv2 clients, just run the [helper script](#using-helper-scripts) again. Refer to the usage information above. Or you may refer to step 4 in [this section](#manually-set-up-ikev2-on-the-vpn-server). ### Export configuration for an existing client By default, the [IKEv2 helper script](#using-helper-scripts) exports client configuration after running. If later you want to export configuration for an existing client, run the helper script again and select the appropriate option. Refer to the usage information above. ### Revoke a client certificate In certain circumstances, you may need to revoke a previously generated VPN client certificate. This can be done using `crlutil`. See example steps below, commands must be run as `root`. 1. Check the database, and identify the nickname of the client certificate you want to revoke. ```bash certutil -L -d sql:/etc/ipsec.d ``` ``` Certificate Nickname Trust Attributes SSL,S/MIME,JAR/XPI IKEv2 VPN CA CTu,u,u ($PUBLIC_IP) u,u,u vpnclient-to-revoke u,u,u ``` In this example, we will revoke the certificate with nickname `vpnclient-to-revoke`, issued by `IKEv2 VPN CA`. 1. Find the serial number of this client certificate. ```bash certutil -L -d sql:/etc/ipsec.d -n "vpnclient-to-revoke" ``` ``` Certificate: Data: Version: 3 (0x2) Serial Number: 00:cd:69:ff:74 ... ... ``` From the output, we see that the serial number is `CD69FF74` in hexadecimal, which is `3446275956` in decimal. It will be used in the next steps. 1. Create a new Certificate Revocation List (CRL). You only need to do this once for each CA. ```bash if ! crlutil -L -d sql:/etc/ipsec.d -n "IKEv2 VPN CA" 2>/dev/null; then crlutil -G -d sql:/etc/ipsec.d -n "IKEv2 VPN CA" -c /dev/null fi ``` ``` CRL Info: : Version: 2 (0x1) Signature Algorithm: PKCS #1 SHA-256 With RSA Encryption Issuer: "O=IKEv2 VPN,CN=IKEv2 VPN CA" This Update: Sat Jun 06 22:00:00 2020 CRL Extensions: ``` 1. Add the client certificate you want to revoke to the CRL. Here we specify the certificate's serial number in decimal, and the revocation time in GeneralizedTime format (YYYYMMDDhhmmssZ) in UTC. ```bash crlutil -M -d sql:/etc/ipsec.d -n "IKEv2 VPN CA" <here. 1. Finally, let Libreswan re-read the updated CRL. ```bash ipsec crls ``` ## Manually set up IKEv2 on the VPN server As an alternative to using the [helper script](#using-helper-scripts), advanced users can manually set up IKEv2. Before continuing, it is recommended to update Libreswan to the latest version. The following example shows how to manually configure IKEv2 with Libreswan. Commands below must be run as `root`. 1. Find the VPN server's public IP, save it to a variable and check. ```bash PUBLIC_IP=$(dig @resolver1.opendns.com -t A -4 myip.opendns.com +short) [ -z "$PUBLIC_IP" ] && PUBLIC_IP=$(wget -t 3 -T 15 -qO- http://ipv4.icanhazip.com) printf '%s\n' "$PUBLIC_IP" ``` Check to make sure the output matches the server's public IP. This variable is required in the steps below. **Note:** Alternatively, you may specify the server's DNS name here. e.g. `PUBLIC_IP=myvpn.example.com`. 1. Add a new IKEv2 connection: ```bash if ! grep -qs '^include /etc/ipsec\.d/\*\.conf$' /etc/ipsec.conf; then echo >> /etc/ipsec.conf echo 'include /etc/ipsec.d/*.conf' >> /etc/ipsec.conf fi ``` **Note:** If you specified the server's DNS name (instead of its IP address) in step 1 above, you must replace `leftid=$PUBLIC_IP` in the command below with `leftid=@$PUBLIC_IP`. ```bash cat > /etc/ipsec.d/ikev2.conf <> /etc/ipsec.d/ikev2.conf <MOBIKE IKEv2 extension allows VPN clients to change network attachment points, e.g. switch between mobile data and Wi-Fi and keep the IPsec tunnel up on the new IP. If your server (or Docker host) is **NOT** running Ubuntu Linux, and you wish to enable MOBIKE support, replace `mobike=no` with `mobike=yes` in the command above. **DO NOT** enable this option on Ubuntu systems or Raspberry Pis. For Libreswan 3.19-3.22: ```bash cat >> /etc/ipsec.d/ikev2.conf <> /etc/ipsec.d/ikev2.conf < Is this a critical extension [y/N]? N ``` Generate VPN server certificate: **Note:** If you specified the server's DNS name (instead of its IP address) in step 1 above, you must replace `--extSAN "ip:$PUBLIC_IP,dns:$PUBLIC_IP"` in the command below with `--extSAN "dns:$PUBLIC_IP"`. ```bash certutil -z <(head -c 1024 /dev/urandom) \ -S -c "IKEv2 VPN CA" -n "$PUBLIC_IP" \ -s "O=IKEv2 VPN,CN=$PUBLIC_IP" \ -k rsa -v 120 \ -d sql:/etc/ipsec.d -t ",," \ --keyUsage digitalSignature,keyEncipherment \ --extKeyUsage serverAuth \ --extSAN "ip:$PUBLIC_IP,dns:$PUBLIC_IP" ``` ``` Generating key. This may take a few moments... ``` 1. Generate client certificate(s), then export the `.p12` file that contains the client certificate, private key, and CA certificate. **Note:** You may repeat this step to generate certificates for additional VPN clients, but make sure to replace every `vpnclient` with `vpnclient2`, etc. To connect multiple VPN clients simultaneously, you must generate a unique certificate for each. Generate client certificate: ```bash certutil -z <(head -c 1024 /dev/urandom) \ -S -c "IKEv2 VPN CA" -n "vpnclient" \ -s "O=IKEv2 VPN,CN=vpnclient" \ -k rsa -v 120 \ -d sql:/etc/ipsec.d -t ",," \ --keyUsage digitalSignature,keyEncipherment \ --extKeyUsage serverAuth,clientAuth -8 "vpnclient" ``` ``` Generating key. This may take a few moments... ``` Export `.p12` file: ```bash pk12util -d sql:/etc/ipsec.d -n "vpnclient" -o vpnclient.p12 ``` ``` Enter password for PKCS12 file: Re-enter password: pk12util: PKCS12 EXPORT SUCCESSFUL ``` Enter a secure password to protect the exported `.p12` file (when importing into an iOS or macOS device, this password cannot be empty). 1. (For iOS clients) Export the CA certificate as `ikev2vpnca.cer`: ```bash certutil -L -d sql:/etc/ipsec.d -n "IKEv2 VPN CA" -a -o ikev2vpnca.cer ``` 1. The database should now contain: ```bash certutil -L -d sql:/etc/ipsec.d ``` ``` Certificate Nickname Trust Attributes SSL,S/MIME,JAR/XPI IKEv2 VPN CA CTu,u,u ($PUBLIC_IP) u,u,u vpnclient u,u,u ``` **Note:** To display a certificate, use `certutil -L -d sql:/etc/ipsec.d -n "Nickname"`. To revoke a client certificate, follow [these steps](#revoke-a-client-certificate). For other `certutil` usage, read here. 1. **(Important) Restart the IPsec service**: ```bash service ipsec restart ``` Before continuing, you **must** restart the IPsec service. The IKEv2 setup on the VPN server is now complete. Follow instructions to [configure VPN clients](#configure-ikev2-vpn-clients). ## Troubleshooting *Read this in other languages: [English](ikev2-howto.md#troubleshooting), [简体中文](ikev2-howto-zh.md#故障排除).* ### Incorrect password when trying to import client config files If you forgot the password for client config files, you may [export configuration for the IKEv2 client](#export-configuration-for-an-existing-client) again. Ubuntu 18.04 users may encounter the error "The password you entered is incorrect" when trying to import the generated `.p12` file into Windows. This is due to a bug in `NSS`. Read more here.

Workaround for the NSS bug on Ubuntu 18.04

**Note:** This workaround should only be used on Ubuntu 18.04 systems running on the `x86_64` architecture. As of 2021-01-21, the IKEv2 helper script was updated to automatically apply this workaround. First, install newer versions of `libnss3` related packages: ``` wget https://mirrors.kernel.org/ubuntu/pool/main/n/nss/libnss3_3.49.1-1ubuntu1.5_amd64.deb wget https://mirrors.kernel.org/ubuntu/pool/main/n/nss/libnss3-dev_3.49.1-1ubuntu1.5_amd64.deb wget https://mirrors.kernel.org/ubuntu/pool/universe/n/nss/libnss3-tools_3.49.1-1ubuntu1.5_amd64.deb apt-get -y update apt-get -y install "./libnss3_3.49.1-1ubuntu1.5_amd64.deb" \ "./libnss3-dev_3.49.1-1ubuntu1.5_amd64.deb" \ "./libnss3-tools_3.49.1-1ubuntu1.5_amd64.deb" ``` After that, [export configuration for the IKEv2 client](#export-configuration-for-an-existing-client) again.

### IKEv2 disconnects after one hour If the IKEv2 connection disconnects automatically after one hour (60 minutes), apply this fix: Edit `/etc/ipsec.d/ikev2.conf` on the VPN server (or `/etc/ipsec.conf` if it does not exist), append these lines to the end of section `conn ikev2-cp`, indented by two spaces: ``` ikelifetime=24h salifetime=24h ``` Save the file and run `service ipsec restart`. As of 2021-01-20, the IKEv2 helper script was updated to include this fix. ### Unable to connect multiple IKEv2 clients To connect multiple IKEv2 clients simultaneously, you must [generate a unique certificate](#add-a-client-certificate) for each. If you are unable to connect multiple IKEv2 clients simultaneously from behind the same NAT (e.g. home router), apply this fix: Edit `/etc/ipsec.d/ikev2.conf` on the VPN server, find the line `leftid=@` and remove the `@`, i.e. replace it with `leftid=`. Save the file and run `service ipsec restart`. Do not apply this fix if `leftid` is a DNS name, which is not affected. As of 2021-02-01, the IKEv2 helper script was updated to include this fix. ### Other known issues 1. The built-in VPN client in Windows may not support IKEv2 fragmentation (this feature requires Windows 10 v1803 or newer). On some networks, this can cause the connection to fail or have other issues. You may instead try the IPsec/L2TP or IPsec/XAuth mode. 1. If using the strongSwan Android VPN client, you must update Libreswan on your server to version 3.26 or above. ### Additional troubleshooting Click here for additional troubleshooting information. ## Remove IKEv2 If you want to remove IKEv2 from the VPN server, but keep the [IPsec/L2TP](clients.md) and [IPsec/XAuth ("Cisco IPsec")](clients-xauth.md) modes, run the [helper script](#using-helper-scripts) again and select the "Remove IKEv2" option. Note that this will delete all IKEv2 configuration including certificates and keys, and **cannot be undone**!

Alternatively, you can manually remove IKEv2. Click here for instructions.

To manually remove IKEv2 from the VPN server, but keep the [IPsec/L2TP](clients.md) and [IPsec/XAuth ("Cisco IPsec")](clients-xauth.md) modes, follow these steps. Commands must be run as `root`. Note that this will delete all IKEv2 configuration including certificates and keys, and **cannot be undone**! 1. Rename (or delete) the IKEv2 config file: ```bash mv /etc/ipsec.d/ikev2.conf /etc/ipsec.d/ikev2.conf.bak ``` **Note:** If you used an older version (before 2020-05-31) of the IKEv2 helper script or instructions, file `/etc/ipsec.d/ikev2.conf` may not exist. In this case, please instead remove the `conn ikev2-cp` section from file `/etc/ipsec.conf`. 1. **(Important) Restart the IPsec service**: ```bash service ipsec restart ``` 1. List certificates in the IPsec database: ```bash certutil -L -d sql:/etc/ipsec.d ``` Example output: ``` Certificate Nickname Trust Attributes SSL,S/MIME,JAR/XPI IKEv2 VPN CA CTu,u,u ($PUBLIC_IP) u,u,u vpnclient u,u,u ``` 1. Delete certificates and keys. Replace "Nickname" below with each certificate's nickname. Repeat these commands for each certificate. When finished, list certificates in the IPsec database again, and confirm that the list is empty. ```bash certutil -F -d sql:/etc/ipsec.d -n "Nickname" certutil -D -d sql:/etc/ipsec.d -n "Nickname" 2>/dev/null ```

## References * https://libreswan.org/wiki/VPN_server_for_remote_clients_using_IKEv2 * https://libreswan.org/wiki/HOWTO:_Using_NSS_with_libreswan * https://libreswan.org/man/ipsec.conf.5.html * https://wiki.strongswan.org/projects/strongswan/wiki/WindowsClients * https://wiki.strongswan.org/projects/strongswan/wiki/AndroidVpnClient * https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/tools/NSS_Tools_certutil * https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/tools/NSS_Tools_crlutil ## License Copyright (C) 2016-2021 Lin Song

This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License Attribution required: please include my name in any derivative and let me know how you have improved it!