DevOps, Cloud & System Administration Hub
Chmod octal permissions, IPv4 subnetting, Nginx reverse proxies, and Crontab parsers.
Included In-Browser Utilities (7)
No Install RequiredLinux Chmod Permissions Matrix
Calculate Unix/Linux file and folder permissions across Owner, Group, and Public/Others.
IPv4 Subnet Mask & Host Sizer
Calculate IPv4 subnet boundaries, total and usable hosts, subnet masks, and wildcard masks.
NGINX Reverse Proxy Sizer
Generate optimized, security-hardened NGINX server blocks for Node.js, Next.js, Python, and Docker backends.
Crontab Schedule Humanizer
Translate standard 5-part crontab expressions into readable English schedules and compute cadence intervals.
Docker Compose Container Sizer
Calculate and generate production Docker Compose service blocks with port exposure and volume bindings.
Semantic Versioning (SemVer) Bumper
Calculate next release version numbers under SemVer 2.0.0 and test dependency compatibility ranges.
Password Entropy & Brute Force Time Calculator
Calculate Shannon entropy in bits, character keyspace, and realistic crack times across modern GPU clusters.
Production Linux Server Hardening & Networking Rules
Sysadmins manage infrastructure security where simple typos can take down mission-critical services or expose sensitive databases. Uploading server configurations or IP layouts to third-party tools creates unacceptable security risks.
Our DevOps suite runs 100% in local browser memory with zero network calls. Calculate octal and symbolic chmod permissions, generate production-ready Nginx reverse proxy blocks with SSL headers, and translate complex crontab schedules.
Network subnet calculations provide instant network IDs, broadcast IPs, and usable host address ranges across standard CIDR notation (/8 through /32).
Frequently Asked Questions
Why should I never use chmod 777 on web server folders?▼
Chmod 777 grants Read, Write, and Execute permissions to everyone on the operating system. Any compromised daemon or uploaded script can overwrite your source code or replace index files with malware. Use 755 for directories and 644 for files instead.
How many usable host IP addresses are in a /24 subnet?▼
A /24 subnet contains 256 total IP addresses ($2^8$). The first address is reserved for the Network ID (e.g., .0) and the last address is reserved for Broadcast (e.g., .255), leaving 254 usable host IP addresses.