Product Management Methodologies – an overview of Agile and Lean

Posted on July 5, 2021March 26, 2022 by Marco Antonio Carcano

Skilled professionals nowadays, besides being skilled on technical matters, are supposed to know how to operate according to the principles of modern product management methodologies such as Agile and Lean. The traditional waterfall approach of gathering all the requirements, design everything as a whole, develop everything and test everything before deploying has been superseded since it cannot bear the demand of a quick time to the market of modern times: it is very likely that the delivery comes too late, when the service is no-more needed. The aim of this post is to explain what you should know about Agile and Lean methodologies so as to operate into teams that use them.

Cryptography quick guide – understand symmetric and asymmetric cryptography and how to use it with OpenSSL

Posted on May 20, 2021July 28, 2022 by Marco Antonio Carcano

When it comes to guarantee data confidentiality on the wire or on the disk we cannot be exempt to know how to use cryptography: this post provides a quick guide of both symmetric and asymmetric cryptography along with an overview of their bricks: RSA and DSA keys, Elliptic Curves keys, PGP Keys, Message Digest, HMAC, digital signature and encipherment. The aim is to provide the necessary terms and concepts to understand how to operate with cryptographic tools, providing examples with openssl.

POSIX compliant filesystems

Posted on May 3, 2021June 28, 2021 by Marco Antonio Carcano

Don’t be tempted to skip this post: you would miss something valuable. Of course most of us know how to operate a filesystem, but the underlying details of POSIX filesystems are not broadly known by most of the people. In this post I describe them quite accurately, trying to keep at a level that may intrigue, but avoiding to be too theoretical. Having such an expertise is certainly one of the things that make the difference from a technician and a skilled professional. In addition to that, this skill may really save your life when facing weird things that sometimes may arise.

SPC-3 Persistent Reservations and Fencing

Posted on April 13, 2021May 15, 2021 by Marco Antonio Carcano

Clustered file systems are powerful but they should be carefully implemented to avoid split brains, since it is very likely that these lead to data corruption. A very effective way to cope with this risk is SCSI fencing: this trick denies access to the shared disks from nodes that are considered failed by the majority of the nodes of the cluster. The only requisite to implement SCSI fencing is that the shared storage should support SPC-3 Persistent Reservations. This post talks about this topic and explains how to configure a stonith device that exploits SCSI fencing.

JSON Web Token – JWT

Posted on April 13, 2021June 15, 2021 by Marco Antonio Carcano

JWT provides a convenient and standard way to securely transport claims from an issuer to its audience over HTTP. It can be used for authentication and authorization purposes, as well as non repudiable information exchange. It's easiness of setup along with the pros of being transportable over a simple and plain-text protocol such as HTTP and of being stateless (session data can simply be put inside the claims) made it be broadly adopted by developers, whenever it does not worth to implement more cumbersome frameworks such as OpenID or OAuth. In this post we explore JWT and its related standards JWS and JWE.

Designing infrastructures – defining corporate’s standard tiers

Posted on April 13, 2021May 15, 2021 by Marco Antonio Carcano

Infrastructures are the foundations used to provide services: since services are subjected to confidentiality and availability requirements, infrastructures must be designed so to provide several confidentiality and availability tiers. This way a service can be placed on the part of the infrastructure that meets the availability and confidentiality requirements for its use case. This means that one of the very first things to do when designing infrastructures is defining the corporate's standard tiers.