Tag Archives: gateway

API Gateway for data egress

11 Wednesday Jan 2023

Posted by in Cloud, General, Technology

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Most larger organizations route their outbound web traffic through a web proxy. The primary motivation for this is to measure where traffic is going. Log traffic for analysis to try and detect activities trying to egress data that should remain within the organization and prevent access to websites that are considered harmful in one form or another.

So why consider an API Gateway as part of an outbound traffic flow? After all, isn’t a Gateway there to protect us? Several very good reasons. Let’s look at them:

  • Managing the use of an external paid service. You may have multiple solutions using a third-party service – for example, an SMS service. Rather than expecting all these different calls to the external API, each having a copy of the 3rd party credentials to manage, we could use the gateway as a single point to attach the credentials.
  • When it comes to being charged for a service, being able to identify the requests at the API level makes it very easy to track your own consumption and forecast forward before being billed. This is really helpful if you have an agreement that provides a good price for pre-booked capacity and a higher charge for overage/capacity not pre-booked.
  • Economies of scale for using 3rd party services can be very powerful. But it can also present two problems.
    • Switching providers quickly can be difficult as multiple points of possible change
    • How to partition the cost of the external service across different departments if everyone is using a common account.

The first of these issues can be easily overcome using the anti-corruption layer pattern where the gateway represents the correct route so it can reformat the requests in one place to work with a different provider.

At the same time, we can more intelligently use Gateway’s metering mechanisms rather than having to implement functionality to mine the proxy’s logs.

Of course you can achieve same effect without a gateway, but you don’t get the benefits that a gateway will offer out of the box. In addition the chances are that you have already got an API Gateway running for your current North-South traffic.

API Gateway Deployment Patterns

14 Tuesday Jan 2020

Posted by in APIs & microservices, General, Oracle, Technology

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When it comes to deployment of API Gateways, there are a couple of well-known patterns, that of the Internal Gateway and External Gateway (described in several resources including here).

These two deployments essentially reflect the considerations of offering endpoints up to less secure network segments such as the internet (external gateways) and trusted network zones (internal gateways). But in addition to the physical deployment within a network, these deployments are likely to host APIs with different characteristics, reflecting levels of trust, and emphasis on enterprise decoupling/abstraction (internal) –  the reason why APIs are sometimes associated with the idea of SOA 2.0. Compared with security sensitivity, and potentially monetization or at least usage metrics to help protect specific attack vectors.

These deployment patterns can be seen in the following diagram.

B06989_05_04

Both the internal and external gateways are reflective of interest in the origin of the API traffic. However a rarer 3rd pattern does exist.

Outbound Gateway

This pattern of crops up when you need to consider the ability to manage how internal solutions connect to outside services, for reasons such as:

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Handling Socket connectivity with API Gateway

30 Friday Aug 2019

Posted by in API Platform CS, General, Oracle, Technology

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At the time of writing the Oracle API Platform doesn’t support the use of Socket connections for handling API data flows. Whilst the API Platform does provide an SDK as we’ve described in other blogs and our book it doesn’t allow the extension of how connectivity is managed.

The use of API Gateways and socket-based connectivity is something that can engender a fair bit of debate – on the one hand, when a client is handling a large volume of data, or expects data updates, but doesn’t want to poll or utilize webhooks then a socket strategy will make sense. Think of an app wanting to listen to a Kafka topic. Conversely, API gateways are meant to be relatively lightweight components and not intended to deal with a single call to result in massive latency as the back-end produces or waits to forward on data as this is very resource-intensive and inefficient. However, a socket-based data transmission should be subject to the same kinds of security controls, and home brewing security solutions from scratch are generally not the best idea as you become responsible for the continual re-verification of the code being secure and handling dependency patching and mitigating vulnerabilities in other areas.

So how can we solve this?

As a general rule of thumb, web sockets are our least preferred way of driving connectivity, aside from the resource demand, it is a fairly fragile approach as connections are subject to the vagaries of network connections, which can drop etc. It can be difficult to manage state (i.e. knowing what data has or hasn’t reached the socket consumer). But sometimes, it just is the right answer. Therefore we have developed the following pattern as the following diagram illustrates.

API Protected Sockets

How it works …

The client initiates things by contacting the gateway to request a socket, with the details of the data wanted to flow through the socket. This can then be validated as both a legitimate request or (API Tokens, OAuth etc) and that the requester can have the data wanted via analyzing the request metadata.

The gateway works in conjunction with a service component and will if approved acquire a URI from the socket manager component. This component will provide a URL for the client to use for the socket request. The URL is a randomly generated string. This means that port scans of the exposed web service are going to be difficult. These URLs are handled in a cache, which ideally has a TTL (Time To Live). By using Something like Redis with its native TTL capabilities means that we can expire the URL if not used.

With the provided URL we could further harden the security by associating with it a second token.

Having received the response by the client, it can then establish the socket-based connection which gets routed around the API Gateway to the Socket component. This then takes the randomly-generated part of the URL and looks up the value in the cache, if it exists in the cache and the secondary token matches then the request for the socket is legitimate. With the socket connection having been accepted the logic that will feed the socket can commence execution.

If the request is some form of malicious intent such as a scan, probe or brute force attempt to call the URL then the attempt should fail because …

  • If the socket URL has never existed in or has been expired from the Cache and the request is rejected.
  • If a genuine URL is obtained, then the secondary key must correctly verify. If incorrect again the request is rejected.
  • Ironically, any malicious attack seeking to overload components is most likely to affect the cache and if this fails, then a brute access tempt gets harder as the persistence of all keys will be lost i.e. nothing to try brute force locate.

You could of course craft in more security checks such as IP whitelisting etc, but every-time this is done the socket service gets ever more complex, and we take on more of the capabilities expected from the API Gateway and aside from deploying a cache, we’ve not built much more than a simple service that creates some random strings and caches them, combined with a cache query and a comparison. All the hard security work is delegated to the gateway during the handshake request.

Thanks to James Neate and Adrian Lowe for kicking around the requirement and arriving at this approach with us.

 

Managing API Gateway Costs with Oracle API Platform

03 Wednesday Jul 2019

Posted by in API Platform CS, APIs & microservices, General, Oracle, Technology

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The Oracle API Platform adopted an intelligent pricing model by basing costs on API call volumes and Logical gateway node groupings per hour. In our book about the API Platform (more here). We suggested that a good logical grouping would be to reflect the development, test, pre-production and production model. This makes it nice and easy to use gateway based routing to different environments without needing to change the API policy configuration as you promote your solution through environments.

We have also leveraged naming and Role/Group Based Access Controls to make it easy to operate the API Platform as a shared service, rather than each team having its own complete instance. In doing so the number of logical gateways needed is limited (I.e. not logical gateway divisions on per team models needed). Group management is very easy through the leveraging of Oracle’s Identity Cloud Service – which is free for managing users on the Oracle solutions, and also happens to a respected product in its own right.

Most organisations are not conducting development and testing 365 days a year, for 24 hours a day (yes in an ideal world prolonged soak and load tests would be run to help tease out cumulative issues such as memory leaks, but even then it isn’t perpetual). As a result, it would be ideal to not be using logical gateways for part of the day such as outside the typical development day, and weekends.

Whilst out of the out of hours traffic may drop to zero calls and we may even shutdown the gateway nodes, this alone doesn’t effectively reduce the number of logical gateways as the logical gateway aspect of the platform counts as soon as you create the logical group in the management portal. This in itself isn’t a problem as the API Platform drinks it’s own Champagne as the saying goes, and everything in the UI is actually available as a published REST endpoint. Something covered in the book, and in previous blog posts (for example Making Scripts Work with IDCS Deployed PaaS and Analytics and Stats for APIs). Rather than providing all the code, you can see pretty much all the calls necessary in the other utilities published.

Before defining the steps, there are a couple of things to consider. Firstly, the version of the API deployed to a specific logical gateway may not necessarily be the latest version (iteration) and when to delete the logical gateway this information is lost, so before deleting the logical gateway we should record this information to allow us to reinstate the logical gateway later.

As deleting logical gateways will remove the gateway from the system, when recreating the gateway we can use the same name, but the gateway is not guaranteed to get the same Id as before, as a result, we should when rebuilding always discover the Id from the name to be safe.

A logical gateway can not be deleted until all the physical nodes are reallocated, so we need to iterate through the nodes removing them. When it comes to reconnecting the nodes, this is a little more tricky as reconnecting the gateway appears to only be achievable with information known to the gateway node. Therefore the simplest thing is when bringing the node back online we take the information from the gateway-props.json file and run a script that determines whether the management tier knows about the node. If not then just re-run the create, start, join cycle., otherwise just run the start command.

As with the logical gateway, re-running the create, deploy, start cycle will result in the node having a new Id. This does mean that whilst the logical gateway name and even the node names will remain the same, the analytics data is likely to become unavailable, so you may wish to extract the analytics data. But then, for development and test, this data is unlikely to provide much long term value.

So based on this, our sequence for releasing the logical gateway needs to be…

  1. Capture the deployed APIs and the iteration numbers,
  2. Ideally shutdown the gateway node process itself,
  3. Delete all the gateway nodes from the logical gateway,
  4. Delete the logical gateway,

Recover would then be …

  1. Construct the logical gateway,
  2. Redeploy the APIs with the correct iteration numbers to the logical gateway using the recorded information- if no nodes are connected at this stage, the UI will provide a warning
  3. As gateway nodes, come back online, determine if it is necessary to execute the create, start, join or just start

Of course, these processes can be all linked to scheduling such as a cron job and/or server startup and shutdown processes.