Technical notes for systems that have to keep working.
Practical notes by Tudor Shandrov on Linux, Proxmox, networking, observability, storage, security and production operations. Focused on decisions, validation and failure modes rather than copy-paste recipes.
Featured notes
All notes →Diagnosing deferred Mailcow delivery: local firewall or remote MX refusal?
A short evidence-driven workflow for distinguishing local SMTP connectivity problems from selective refusal by a remote mail server.
Monitoring Proxmox VE with Prometheus using API tokens and a trusted CA
A production-oriented pattern for collecting Proxmox metrics without disabling TLS verification or using a full administrator account.
Migrating Ceph authentication keys to aes256k without losing cluster access
A staged operational approach to rotating Ceph service and client keys while preserving quorum and administrative access.
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Diagnosing deferred Mailcow delivery: local firewall or remote MX refusal?
A short evidence-driven workflow for distinguishing local SMTP connectivity problems from selective refusal by a remote mail server.
Monitoring Proxmox VE with Prometheus using API tokens and a trusted CA
A production-oriented pattern for collecting Proxmox metrics without disabling TLS verification or using a full administrator account.
Migrating Ceph authentication keys to aes256k without losing cluster access
A staged operational approach to rotating Ceph service and client keys while preserving quorum and administrative access.