Tech

This article describes the process of configuring Keycloak for passwordless login using passkeys, webauthn, and OTP (One-Time Password). Some configurations in this article may require Keycloak 23 or higher to function properly. Configuring the Authentication Section In Keycloak’s Authentication - Flow menu, duplicate the browser flow. We’ll name the copy browser with optional webauth and otp. Duplicate Browser Flow In the new flow, delete browser password form and all steps/flows below it: ...

Recently, our laboratory acquired eight NVMe SSDs, which we connected to a server via PCIe adapter cards and configured into a RAID using ZFS. To enable rapid access to the storage pool from other servers in the lab, I picked up two ConnectX-4 CX4121A 10GbE network cards from a second-hand platform to link two servers, and set up NFS over RDMA. The seller on the second-hand platform did not include optical modules, so I randomly purchased two 10G Huawei modules, costing about 15-20 RMB each. ...

I recently obtained several “removable eSIM cards” from esim.me from a friend in a group chat. In short, these eSIM cards are manufactured in the form of ordinary SIM cards, so they can be directly inserted into any mobile phone that supports physical SIM cards, and profiles can be added to the eSIM cards through the Android app provided by esim.me. Although esim.me differentiates the prices of these eSIM cards based on the number of profiles that each eSIM card can join, when I later searched for blog posts online, some people mentioned that the hardware of these eSIM cards at different price points is exactly the same, and esim.me only imposed software restrictions on cards at different price points through the mobile configuration app. And if these eSIM cards are inserted into LTE modules that support eSIM, profiles can be directly added and deleted through the Windows eSIM management interface. However, the current LTE modules that support eSIM are mainly Quectel’s RM-50xQ series (used price 550 yuan) and Dell’s dw5821e (used price 300 yuan) / dw5829e modules. It’s obviously not cost-effective to purchase these LTE modules just to configure the eSIM card. ...

In many parts of the world, mobile phone numbers are increasingly intertwined with online services and personal identity. This is particularly true in mainland China, where a single user may find themselves managing multiple phone numbers for various applications and platforms. While solutions like telegram-sms and SMS-forwarder have emerged to address the inconvenience of managing multiple physical SIM cards, they come with limitations. These apps, typically installed on smartphones, are often hampered by aggressive background process management common on Android devices, leading to unreliable SMS forwarding. Furthermore, the practice of keeping older devices powered on long-term for this purpose introduces safety concerns, such as battery swelling. Perhaps the most significant limitation is the inability to handle phone calls; these apps only address SMS. This article details a project where the author, using an EC20 cellular module and a blend of software tools like asterisk, to overcame these limitations. The setup allows for SMS messaging through instant messaging applications like Telegram, and makes and receives phone calls over the internet using SIP clients, providing a more robust and flexible solution. ...