Calculate octal numbers and symbolic notation for Linux server files and folders to keep web servers safe from attacks.
Setting file permissions on Linux servers determines who can read, write, or execute files. Using incorrect permissions can either break website loading or leave servers vulnerable to unauthorized edits. Standard web permissions follow simple best practices.
Worked example: Set secure permissions for a public website folder
Input
Owner has Read, Write, Execute; Group has Read, Execute; Public has Read, Execute.
Expected result
Octal notation 755 (rwxr-xr-x) with the terminal command: chmod 755 foldername.
755 allows the web server to access and serve folder files, while preventing unauthorized outside visitors from modifying files.
Before you use the result
- Use 755 for standard web directories and executable scripts.
- Use 644 for standard files (HTML, images, CSS) so visitors can view them without editing rights.
- Never use 777 on public production servers as it grants everyone full write access.
If the result is not what you expected
Visitors get a 403 Forbidden error on my website.
The folder or file permissions are likely too restrictive. Check that web folders are set to 755 and HTML/image files are set to 644.
Step-by-Step Walkthrough
Select Permissions
Check the read, write, and execute boxes for owner, group, and others.
Or Use a Preset
Click standard options like 644 for public files or 755 for scripts.
Copy Command
Copy the numeric code or the full terminal command.
Key Capabilities & Features
Interactive 3x3 permission matrix for Owner, Group, and Public access
Instant conversion between numeric octal notation and symbolic flags (rwxr-xr-x)
Quick preset buttons for common server setups like 755, 644, and 777
Ready-to-copy terminal commands for individual files or recursive folders
Frequently Asked Questions
Ready to try Chmod Permissions Calculator?
Open Chmod Permissions Calculator and try the example from this guide. Check the tool page for supported formats, limits, and access requirements.