CYBERTOOLS / 0x2A
[SYS_NODE: 0x2A // UNIX PERMISSION MATRIX]

CHMOD PERMISSIONS CALCULATOR

Visual interactive Unix permissions grid. Bidirectionally converts between octal notation (755, 644, 600) and symbolic flags (-rwxr-xr-x). Computes terminal commands for files, scripts, and recursive directory trees.

SECURITY PRESETS:
OCTAL NOTATION VALUE
[EDITABLE]
Owner: 7 (rwx) | Group: 5 (r-x) | Public: 5 (r-x)
SYMBOLIC NOTATION VALUE
[EDITABLE]
File Type: Regular File (-)
PERMISSION MATRIX
OWNER (USER) 7
GROUP 5
OTHERS (PUBLIC) 5
COPYABLE TERMINAL EXECUTION SNIPPETS
Standard Octal:
chmod 755 filename
Symbolic Syntax:
chmod u=rwx,g=rx,o=rx filename
Recursive Directory:
chmod -R 755 /path/to/directory/

UNIX DISCRETIONARY ACCESS CONTROL (DAC) & PERMISSION ARCHITECTURE

Technical specifications for POSIX permission bits, octal calculation mathematics, symbolic operators, and hardened security best practices.

1. Binary Weight Mathematics

Unix file permissions are implemented as a set of 9 primary bit flags organized into three distinct triplets (User, Group, Other). Each bit corresponds to an exact power of two:

  • Read (r): Bit value 4 (binary 100). Grants read access to file contents or directory file listings.
  • Write (w): Bit value 2 (binary 010). Grants file modification and directory file creation/deletion rights.
  • Execute (x): Bit value 1 (binary 001). Grants binary program execution or directory directory-traversal (cd).

2. Standard Security Baselines

Hardened POSIX environments enforce strict principle of least privilege permissions:

600 / 400 (Private Keys) Required by OpenSSH for id_rsa and TLS private keys. The SSH client will reject keys with group/other permissions.
644 (Static Assets) Standard baseline for HTML, CSS, JS, and server assets. Owner can write; world can only read.
755 (Executables) Standard for system binaries, shell scripts, and web server directories allowing directory traversal.
1. Air-Gapped Privacy 100% in-browser calculations. No terminal logs, paths, or file telemetry are transmitted externally.
2. Bidirectional Parsing Seamlessly calculate between octal numbers and symbolic strings in real time without page refreshes.
3. Automated Risk Audits Integrated warning triggers whenever insecure flags (777) are detected.