14.12.2020

Azure Pre Shared Key Generator

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Azure S2S VPN connections provide secure, cross-premises connectivity between customer premises and Azure. This tutorial walks through IPsec S2S VPN connection life cycles such as creating and managing a S2S VPN connection. You learn how to:

If the PSK (Pre-Shared Key) is too short, or too long, an alert will pop up saying the following: 'The secret must be at least six characters long, no more than 64 characters, and contain four different characters'.

Sign in to the Azure dashboard. In the navigation pane, click on All Resources. Choose the desired storage account. Click on the Key icon to view the access keys for the storage account. Note: Each storage account has two storage access keys. To copy a storage access key, click on the Copy icon next to the key you want to copy. Azure S2S VPN connection uses a pre-shared key (secret) to authenticate between your on-premises VPN device and the Azure VPN gateway. You can view and update the pre-shared key for a connection with Get-AzVirtualNetworkGatewayConnectionSharedKey and Set-AzVirtualNetworkGatewayConnectionSharedKey. Pre-shared keys. Let's start with an easy authentication option: pre-shared keys. For pre-shared key authentication to work, a common key is defined on each host. The key definition binds the key to the remote peer's ISAKMP identity. From a security perspective, the pest practice is to use a unique key for each peer pair. Jul 25, 2016  Last week I’ve did an implementation of Microsoft Intune for managing mobile devices. In this setup I’ve configured several settings including a WiFi profile with Pre-Shared key. May 28, 2015 The downside to creating a WiFi policy with a Pre-Shared Key is the hoops you have to jump through. So instead of using Apple Configurator or locating the WiFi XML File on a Windows device you can use these PSK XML Generators. Android WiFi PSK XML Generator 1. The pre-shared key to be encrypted can be configured either as standard, under an ISAKMP key ring, in aggressive mode, or as the group password under an EzVPN server or client setup. This sample configuration details how to set up encryption of both existing and new pre-shared keys.

  • Create an S2S VPN connection
  • Update the connection property: pre-shared key, BGP, IPsec/IKE policy
  • Add more VPN connections
  • Delete a VPN connection

The following diagram shows the topology for this tutorial:

Working with Azure Cloud Shell and Azure PowerShell

This article uses PowerShell cmdlets. To run the cmdlets, you can use Azure Cloud Shell. The Azure Cloud Shell is a free interactive shell that you can use to run the steps in this article. It has common Azure tools preinstalled and configured to use with your account.

To open the Cloud Shell, just select Try it from the upper right corner of a code block. You can also launch Cloud Shell in a separate browser tab by going to https://shell.azure.com/powershell. Select Copy to copy the blocks of code, paste it into the Cloud Shell, and press enter to run it.

Requirements

Complete the first tutorial: Create VPN gateway with Azure PowerShell to create the following resources:

  1. Resource group (TestRG1), virtual network (VNet1), and the GatewaySubnet
  2. VPN gateway (VNet1GW)
Azure

The virtual network parameter values are listed below. Note the additional values for the local network gateway which represent your on-premises network. Change the values below based on your environment and network setup, then copy and paste to set the variables for this tutorial. If your Cloud Shell session times out, or you need to use a different PowerShell window, copy and paste the variables to your new session and continue the tutorial.

Note

If you are using this to make a connection, be sure to change the values to match your on-premises network. If you are just running these steps as a tutorial, you don't need to make changes, but the connection will not work.

The workflow to create an S2S VPN connection is straightforward:

  1. Create a local network gateway to represent your on-premises network
  2. Create a connection between your Azure VPN gateway and the local network gateway

Create a local network gateway

A local network gateway represents your on-premises network. You can specify the properties of your on-premises network in the local network gateway, including:

  • Public IP address of your VPN device
  • On-premises address space
  • (Optional) BGP attributes (BGP peer IP address and AS number)

Create a local network gateway with the New-AzLocalNetworkGateway command.

Create a S2S VPN connection

Next, create a Site-to-Site VPN connection between your virtual network gateway and your VPN device with the New-AzVirtualNetworkGatewayConnection. Notice that the '-ConnectionType' for Site-to-Site VPN is IPsec.

Add the optional '-EnableBGP $True' property to enable BGP for the connection if you are using BGP. It is disabled by default. Parameter '-ConnectionProtocol' is optional with IKEv2 as default. You can create the connection with IKEv1 protocols by specifying -ConnectionProtocol IKEv1.

Update the VPN connection pre-shared key, BGP, and IPsec/IKE policy

View and update your pre-shared key

Azure S2S VPN connection uses a pre-shared key (secret) to authenticate between your on-premises VPN device and the Azure VPN gateway. You can view and update the pre-shared key for a connection with Get-AzVirtualNetworkGatewayConnectionSharedKey and Set-AzVirtualNetworkGatewayConnectionSharedKey.

Important

The pre-shared key is a string of printable ASCII characters no longer than 128 in length.

This command shows the pre-shared key for the connection:

The output will be 'Azure@!b2C3' following the example above. Use the command below to change the pre-shared key value to 'Azure@!_b2=C3':

Enable BGP on VPN connection

Azure VPN gateway supports BGP dynamic routing protocol. You can enable BGP on each individual connection, depending on whether you are using BGP in your on-premises networks and devices. Specify the following BGP properties before enabling BGP on the connection:

  • Azure VPN ASN (Autonomous System Number)
  • On-premises local network gateway ASN
  • On-premises local network gateway BGP peer IP address

If you have not configured the BGP properties, the following commands add these properties to your VPN gateway and local network gateway: Set-AzVirtualNetworkGateway and Set-AzLocalNetworkGateway.

Use the following example to configure BGP properties:

Enable BGP with Set-AzVirtualNetworkGatewayConnection.

You can disable BGP by changing the '-EnableBGP' property value to $False. Refer to BGP on Azure VPN gateways for more detailed explanations of BGP on Azure VPN gateways.

Apply a custom IPsec/IKE policy on the connection

You can apply an optional IPsec/IKE policy to specify the exact combination of IPsec/IKE cryptographic algorithms and key strengths on the connection, instead of using the default proposals. The following sample script creates a different IPsec/IKE policy with the following algorithms and parameters:

  • IKEv2: AES256, SHA256, DHGroup14
  • IPsec: AES128, SHA1, PFS14, SA Lifetime 14,400 seconds & 102,400,000 KB

Refer to IPsec/IKE policy for S2S or VNet-to-VNet connections for a complete list of algorithms and instructions.

Add another S2S VPN connection

Add an additional S2S VPN connection to the same VPN gateway, create another local network gateway, and create a new connection between the new local network gateway and the VPN gateway. Use the following examples, making sure to modify the variables to reflect your own network configuration.

There are now two S2S VPN connections to your Azure VPN gateway.

Delete a S2S VPN connection

Delete a S2S VPN connection with Remove-AzVirtualNetworkGatewayConnection.

Delete the local network gateway if you no longer need it. You cannot delete a local network gateway if there are other connections associated with it.

Clean up resources

If this configuration is part of a prototype, test, or proof-of-concept deployment, you can use the Remove-AzResourceGroup command to remove the resource group, the VPN gateway, and all related resources.

Next steps

In this tutorial, you learned about creating and managing S2S VPN connections such as how to:

  • Create an S2S VPN connection
  • Update the connection property: pre-shared key, BGP, IPsec/IKE policy
  • Add more VPN connections
  • Delete a VPN connection

/could-not-generate-key-in-keystore-samsung-galaxy-s4-mini.html. Advance to the following tutorials to learn about S2S, VNet-to-VNet, and P2S connections.

Pre-shared keys (PSK) are the most common authentication method for site-to-site IPsec VPN tunnels. So what’s to say about the security of PSKs? What is its role for the network security? How complex should PSKs be? Should they be stored additionally? What happens if an attacker catches my PSKs?

I am listing my best practice steps for generating PSKs.

This is one of many VPN tutorials on my blog. –> Have a look at this full list. <–

Pre-Shared Keys in IPsec

The following section is related to site-to-site VPNs only and NOT to remote access VPNs.

  1. The pre-shared key is merely used for authentication, not for encryption! IPsec tunnels rely on the ISAKMP/IKE protocols to exchange the keys for encryption, etc. But before IKE can work, both peers need to authenticate each other (mutual authentication). This is the only part in which the PSKs are used (RFC 2409).
  2. If static IP addresses are used on both sides (= main mode can be used), an attacker who has the PSK must also spoof/redirect these public addresses over himself in order to establish a VPN connection. That is: Even if an attacker has a PSK, he must spoof a public IP address to use it to authenticate against the other side. This is quite unrealistic for normal persons with common ISP connections. Even skilled hackers must be able to inject falsified BGP routes or to sit nearby the customers default gateway/router.
  3. But: If one remote side has only a dynamic IP address, IKE must use the aggressive mode for its authentication. In this scenario, a hash from the PSK traverses the Internet. An attacker can do an offline brute-force attack against this hash. That is: If the PSK is not complex enough, the attacker could succeed and would be able to establish a VPN connection to the network (if he furthermore knows the IDs of the site-to-site VPN peers which is no problem since they traverse through the Internet in plaintext, too).

Best Practice for PSKs

Since the PSKs must be configured on each side only once, it should be no problem to write 20-40 letters on the firewall. Thereby, a really complex key can be generated and used for the authentication of the VPN peer. Here are my tips:

  1. Generate a new/different PSK for every VPN tunnel.
  2. Use a password/passphrase generator for the creation of the PSK.
  3. Generate a long PSK with at least 30 chars, to resist a brute-force attack. (See my article about password complexity.) To avoid problems, use only alphanumeric chars. Since the PSK with 30 chars is really long, the “small” character set of only 62 alphabets and numerals is no problem. The security level in this example would be round about 178 bit (since ).
  4. Do NOT send the PSK to your peer over the Internet, but via phone, fax, or SMS.
  5. There is no need to store the PSK anywhere else. If it is configured on both sides, you can discard it. In the worst case, you need to generate and transfer a new one.

Further Reading

  • RFC 2409: The Internet Key Exchange (IKE)
  • RFC 4301: Security Architecture for the Internet Protocol
  • Michael Thumann, Enno Rey: PSK Cracking using IKE Aggressive Mode [PDF]
  • eTutorials: Attacking IPsec VPNs

Azure Pre Shared Key Generator Reviews

Featured image: “Scrabble” by Wasili is licensed under CC BY-NC-ND 2.0.