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Announcing Anycast IPsec: a new on-ramp to Cloudflare One


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Announcing Anycast IPsec: a new on-ramp to Cloudflare One

Today, we're excited to announce support for IPsec as an on-ramp to Cloudflare One. As a customer, you should be able to use whatever method you want to get your traffic to Cloudflare's network. We've heard from you that IPsec is your method of choice for connecting to us at the network layer, because of its near-universal vendor support and blanket layer of encryption across all traffic. So we built support for it! Read on to learn how our IPsec implementation is faster and easier to use than traditional IPsec connectivity, and how it integrates deeply with our Cloudflare One suite to provide unified security, performance, and reliability across all your traffic.

Using the Internet as your corporate network

With Cloudflare One, customers can connect any traffic source or destination — branch offices, data centers, cloud properties, user devices — to our network. Traffic is routed to the closest Cloudflare location, where security policies are applied before we send it along optimized routes to its destination — whether that’s within your private network or on the Internet. It is good practice to encrypt any traffic that’s sensitive at the application level, but for customers who are transitioning from forms of private connectivity like Multiprotocol Label Switching (MPLS), this often isn’t a reality. We’ve talked to many customers who have legacy file transfer and other applications running across their MPLS circuits unencrypted, and are relying on the fact that these circuits are “private” to provide security. In order to start sending this traffic over the Internet, customers need a blanket layer of encryption across all of it; IPsec tunnels are traditionally an easy way to accomplish this.

Traditional IPsec implementations

IPsec as a technology has been around since 1995, and is broadly implemented across many hardware and software platforms. Many companies have adopted IPsec VPNs for securely transferring corporate traffic over the Internet. These VPNs tend to have one of two main architectures: hub and spoke, or mesh.

Hub and spoke architecture

In the hub and spoke model, each “spoke” node establishes an IPsec tunnel back to a core “hub,” usually a headquarters or data center location. Traffic between spokes flows through the hub for routing and in order to have security policies applied (like by an on-premise firewall). This architecture is simple because each node only needs to maintain one tunnel to get connectivity to other locations, but it can introduce significant performance penalties. Imagine a global network with two “spokes”, one in India and another one in Singapore, but a “hub” located in the United States — traffic needs to travel a round trip thousands of miles back and forth in order to get to its destination.

Mesh architecture

In the mesh model, every node is connected to every other node with a dedicated IPsec tunnel. This improves performance because traffic can take more direct paths, but in practice means an unmanageable number of tunnels after even a handful of locations are added.

Customers we’ve talked to about IPsec know they want it for the blanket layer of encryption and broad vendor support, but they haven’t been particularly excited about it because of the problems with existing architecture models. We knew we wanted to develop something that was easier to use and left those problems in the past, so that customers could get excited about building their next-generation network on Cloudflare. So how are we bringing IPsec out of the 90s? By delivering it on our global Anycast network: customers establish one IPsec tunnel to us and get automatic connectivity to 250+ locations. It’s conceptually similar to the hub and spoke model, but the “hub” is everywhere, blazing fast, and easy to manage.

So how does IPsec actually work?

IPsec was designed back in 1995 to provide authentication, integrity, and confidentiality for IP packets. One of the ways it does this is by creating tunnels between two hosts, encrypting the IP packets, and adding a new IP header onto encrypted packets. To make this happen, IPsec has two components working together: a userspace Internet Key Exchange (IKE) daemon and an IPsec stack in kernel-space. IKE is the protocol which creates Security Associations (SAs) for IPsec. An SA is a collection of all the security parameters, like those for authentication and encryption, that are needed to establish an IPsec tunnel.

When a new IPsec tunnel needs to be set up, one IKE daemon will initiate a session with another and create an SA. All the complexity of configuration, key negotiation, and key generation happens in a handful of packets between the two IKE daemons safely in userspace. Once the IKE Daemons have started their session, they hand off their nice and neat SA to the IPsec stack in kernel-space, which now has all the information it needs to intercept the right packets for encryption and decryption.

There are plenty of open source IKE daemons, including strongSwan, Libreswan, and Openswan, that we considered using for our IPsec implementation. These “swans” all tie speaking the IKE protocol tightly with configuring the IPsec stack. This is great for establishing point-to-point tunnels — installing one “swan” is all you need to speak IKE and configure an encrypted tunnel. But we’re building the next-generation network that takes advantage of Cloudflare’s entire global Anycast edge. So how do we make it so that a customer sets up one tunnel with Cloudflare with every single edge server capable of exchanging data on it?

Anycast IPsec: an implementation for next-generation networks

The fundamental problem in the way of Anycast IPsec is that the SA needs to be handed off to the kernel-space IPsec stack on every Cloudflare edge server, but the SA is created on only one server — the one running the IKE daemon that the customer’s IKE daemon connects to. How do we solve this problem? The first thing that needs to be true is that every server needs to be able to create that SA.

Every Cloudflare server now runs an IKE daemon, so customers can have a fast, reliable connection to start a tunnel anywhere in the world. We looked at using one of the existing “swans” but that tight coupling of IKE with the IPsec stack meant that the SA was hard to untangle from configuring the dataplane. We needed the SA totally separate and neatly sharable from the server that created it to every other server on our edge. Naturally, we built our own “swan” to do just that.

To send our SA worldwide, we put a new spin on an old trick. With Cloudflare Tunnels, a customer’s cloudflared tunnel process creates connections to a few nearby Cloudflare edge servers. But traffic destined for that tunnel could arrive at any edge server, which needs to know how to proxy traffic to the tunnel-connected edge servers. So, we built technology that enables an edge server to rapidly distribute information about its Cloudflare Tunnel connections to all other edge servers.

Fundamentally, the problem of SA distribution is similar -- a customer’s IKE daemon connects to a single Cloudflare edge server’s IKE daemon, and information about that connection needs to be distributed to every other edge server. So, we upgraded the Cloudflare Tunnel technology to make it more general and are now using it to distribute SAs as part of Anycast IPsec support. Within seconds of an SA being created, it is distributed to every Cloudflare edge server where a streaming protocol applies the configuration to the kernel-space IPsec stack. Cloudflare’s Anycast IPsec benefits from the same reliability and resilience we’ve built in Cloudflare Tunnels and turns our network into one massively scalable, resilient IPsec tunnel to your network.

On-ramp with IPsec, access all of Cloudflare One

We built IPsec as an on-ramp to Cloudflare One on top of our existing global system architecture, putting the principles customers care about first. You care about ease of deployment, so we made it possible for you to connect to your entire virtual network on Cloudflare One with a single IPsec tunnel. You care about performance, so we built technology that connects your IPsec tunnel to every Cloudflare location, eliminating hub-and-spoke performance penalties. You care about enforcing security policies across all your traffic regardless of source, so we integrated IPsec with the entire Cloudflare One suite including Magic Transit, Magic Firewall, Zero Trust, and more.

IPsec is in early access for Cloudflare One customers. If you’re interested in trying it out, contact your account team today!

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Annika Garbers|@annikagarbers
Michael Vanderwater|@MVanderwater

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