Linux

The most powerful tool you can have is the ability to move information freely. Efficiently transferring files between your host machine and a QEMU‑emulated Buildroot system becomes essential when testing kernel modules, applications, or firmware artifacts. This guide explains how to enable SSH inside Buildroot, verify connectivity, and use scp to move files seamlessly from host to guest. Prerequisite Before proceeding, ensure your Buildroot filesystem includes the OpenSSH server. Inside Buildroot, enable: ...

Overview Buildroot is a powerful tool that automates building cross‑compilers, kernel images, bootloaders, root filesystems, and entire minimal Linux environments. Combined with QEMU, it provides a fast and fully emulated setup without needing physical hardware. Steps 0. Dependencies Before building Buildroot, ensure the following packages are installed on your host system: For Debian/Ubuntu: sudo apt install build-essential git wget cpio unzip rsync bc python3 \ qemu-system-arm qemu-system-misc qemu-utils flex bison libssl-dev For Fedora: ...

Android and Linux systems rely on various communication methods for processes and threads to interact. Linux provides several IPC (Inter-Process Communication) mechanisms such as pipes, message queues, shared memory, sockets, semaphores, and signals. Android adds its own Binder IPC mechanism, which is widely used for communication between system components and apps. The Zygote process uses sockets for communication, while higher-level services (System Server, Media Server, Apps) primarily use Binder. For communication within the same process, especially between threads, Android uses the Handler message mechanism. ...

Overview ssh-audit is a tool for ssh server & client configuration auditing(banner, key exchange, encryption, mac, compression, compatibility, security, etc). Installation On Arch pacman -S ssh-audit pip pip3 install ssh-audit Generic - Download and extract tarball from release Usage ./ssh-audit.py 192.168.101.201 References https://github.com/jtesta/ssh-audit https://www.ssh-audit.com/hardening_guides.html

Install nfs-kernel-server mkdir ~/Public Export the rootfs folder Add the following entry to /etc/exports: /home/rishav/Public *(rw,async,nohide,insecure,no_root_squash,no_subtree_check) Update the NFS server’s exports sudo exportfs -arv Make the NFS server serve over UDP Add the following to /etc/nfs.conf [nfsd] udp=y vers2=y Restart the NFS server systemctl restart nfs-server.service

Compression Format Comparison Format Compression Ratio Speed (Compression/ Decompression) Encryption Speciality/Uniqueness Open Source/ License gz (.gz) Moderate Fast / Fast No native (use gpg) Widely supported and fast for most general uses. Yes GNU GPL bzip2 (.bz2) Better than gzip Slow / Moderate No native (use gpg) Higher compression ratio and robust error detection. Yes BSD xz (.xz) Best Very slow / Fast No native (use gpg) Highest compression ratio; slow compression speed. Yes GNU GPL zip (.zip) Moderate Fast / Fast Built-in encryption Commonly used with built-in encryption and wide software support. Yes Various (Info-ZIP) tar (.tar) Depends on method Fast (archive only) / Fast (archive only) No native (use gpg) Primarily used for archiving; compression depends on additional tools. Yes GNU GPL 7z (.7z) Excellent Moderate / Slow at high settings AES-256 encryption Excellent compression with advanced encryption options. Yes LGPL rar (.rar) Good Moderate / Moderate AES-256 encryption Includes error recovery and strong encryption; proprietary format. No Proprietary lzma (.lzma) Very high Very slow / Moderate No native (use gpg) High compression ratio with reliable decompression; requires separate decompressor. Yes GNU GPL Key Points gz (.gz): Well-rounded for speed and compatibility, commonly used for general purposes. bzip2 (.bz2): Provides a higher compression ratio compared to gzip, though slower. xz (.xz): Offers the best compression ratio but at the cost of slower compression speed. zip (.zip): Convenient with built-in encryption and broad compatibility. tar (.tar): Primarily an archiving format; often used in combination with other compression methods. 7z (.7z): Excellent compression and strong encryption; requires specific software for full support. rar (.rar): Known for robust recovery features and encryption, but is proprietary. lzma (.lzma): Delivers a high compression ratio and reliable decompression, though it’s slow.

Official Description The cu command is used to call up another system and act as a dial-in terminal (mostly on a serial line ie. serial monitor). It can also do simple file transfers with no error checking. cu is part of the UUCP(Unix to Unix Copy Program) source but has been split into its own package because it can be useful even if you do not do uucp. Usage Start ...

Sections Executable programs or shell commands System calls (functions provided by the kernel) Library calls (functions within program libraries) Special files (usually found in /dev) File formats and conventions, e.g. /etc/passwd Games Miscellaneous (including macro packages and conventions), e.g. man(7), groff(7), man-pages(7) System administration commands (usually only for root) Kernel routines (Non standard) To see if any COMMAND has available sections use whatis of man -f man -f COMMAND

What is Operating System ? An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. What is Kernel? The kernel is a part of operating system which has complete control over everything in the system. It is the portion of the operating system code that is always resident in memory,[2] and facilitates interactions between hardware and software components. What is Linux? Linux is a clone of the operating system Unix, written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX and Single UNIX Specification compliance. ...

Preparation Install Dependencies sudo pacman -S base-devel xmlto kmod inetutils bc libelf git --needed Downloading source and local setup It is recommended to create a separate build directory for your kernel(s). In this example, the directory kernelbuild will be created in the home directory: mkdir ~/kernelbuild cd ~/kernelbuild Goto kernel.org and download kernel source wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.14.5.tar.xz Note: you can verify signature of the downloaded tarball if you want Extract tarball tar -xvJf linux-5.14.5.tar.xz Check ...