The recent articles cover the primitives an attacker and a defender both work with: authentication, permissions, ACLs and file attributes, namespaces and isolation, SECCOMP filtering and the Linux Security Modules on top of it.
Older French articles cover day-to-day administration: SSH access, hard and symbolic links, backups, and intrusion testing against a running service.
19 posts
How Ubuntu uses AppArmor to restrict unprivileged user namespaces, why that stops the headless Chrome behind sol2uml's PNG export, and five remediations.
2026, Oct 15 —
How a system call crosses from user space to the kernel (svc, syscall number, ABI registers), how compiler and linker build an ELF image, and what a process is.
2026, Sep 16 —
The five process states and their transitions, what a thread owns and shares, the TCB, pthread_create/join/exit, and why two threads on a counter lose updates.
2026, Sep 16 —
What a Process Control Block holds, how fork(), exec(), waitpid() and exit() create, replace and reap processes, and what a context switch costs the kernel.
2026, Sep 16 —
How descriptor tables point into the kernel open-file table, what dup2() redirects, the IPC families, and how pipe(), fork() and exec() build ls | more.
2026, Sep 16 —
Fail2Ban reads logs and rewrites the firewall as root. Its jail architecture, the tag-escaping pipeline, and why a filter regex is a security boundary.
2026, Sep 03 —
How sshsig signs arbitrary files with an SSH key, why the namespace field prevents cross-protocol replay, and how allowed_signers controls verification.
2026, Aug 27 —
How the OpenSSH SFTP client keeps requests in flight, ramps its window from one to sixty-four, negotiates buffer sizes with the server and backs scp.
2026, Aug 27 —
How ControlMaster works in OpenSSH, the mux protocol spoken over the ControlPath socket, and the difference between passenger mode and proxy mode.
2026, Aug 27 —
How channels.c implements port forwarding, X11, SOCKS proxying, agent access and tunnels as one abstraction, with per-channel windows and half-close.
2026, Aug 27 —
How an OpenSSH certificate is validated, why unknown critical options are fatal while unknown extensions are ignored, and how KRL revocation lists compress.
2026, Aug 27 —
A technical survey of Linux isolation primitives (mount options, chroot, netfilter, cgroups, namespaces) and how they compose into containers, hypervisors, and Qubes OS as defense in depth.
2026, Jun 29 —
A technical walkthrough of the base GNU/Linux security primitives - login and authentication, POSIX file permissions, ACLs, extended attributes, and capabilities - with their adversary models and trade-offs.
2026, Jun 29 —
Testing GNU/Linux security by bypassing its primitives - stack buffer overflows and their mitigations, the boot chain under a physical adversary, and a remote attack from web exploit to root.
2026, Jun 29 —
How SECCOMP filters system calls and how Linux Security Modules (SELinux, AppArmor, and others) add mandatory access control on top of the base UNIX permission model.
2026, Jun 29 —
Cet article présente la réalisation d'un backup "fait maison" sous le système d'exploitation Ubuntu 18.04 LTS
2021, Nov 05 —
cet article présente un test d'intrusion sur une ancien version d'un serveur apache tomcat afin de sensibiliser le lecteur aux différentes vulnérabilités possibles pour qu'il s'en prémunisse.
2021, Oct 19 —
Cet article présente comment accéder à distance à un shell ainsi que la mise en place d'une connexion sécurisée entre un client et un serveur.
2021, Oct 14 —
Cet article présente les liens symboliques et physiques sur un système d'exploitation GNU/Linux
2021, Jun 15 —
