The network and systems admin
toolbox.
Plan subnets, read cron schedules and permissions, and checksum files without sending anything out.
Keep this toolbox for offline use
15 useful places to start.
Address maths follows the standard CIDR rules. Cron times are UTC and use classic Vixie semantics. MD5 and SHA-1 are for comparison only, not security.
IPv4 subnet calculator
Find the network, broadcast, host range, mask and address type from a CIDR block.
VLSM subnet planner
Split one network into right-sized subnets for departments, links and VLANs.
IP range to CIDR converter
Turn a first and last IPv4 address into the smallest list of CIDR blocks.
IPv6 address formatter
Compress, expand and classify an IPv6 address, with an optional prefix range.
Unix chmod calculator
Convert between octal and symbolic Unix permissions, including setuid, setgid and sticky bits.
Cron expression explainer
Read a five-field cron schedule in plain terms and list its next run times.
Bitwise calculator
Run AND, OR, XOR, shifts and rotates on fixed-width integers in decimal, hex and binary.
MD5, SHA-1, CRC-32 and Adler-32 generator
Compute classic checksums for text or hex bytes without uploading anything.
SHA hash generator
Create SHA-256, SHA-384 or SHA-512 hashes of text.
Number base converter
Convert whole numbers between bases 2 to 36 exactly.
Data transfer rate converter
Convert data transfer rate units with clearly labelled standards.
File transfer time estimate
Estimate a transfer duration from file size, link rate and achieved efficiency.
Base64 encoder & decoder
Encode Unicode text to Base64, or decode it back.
UUID generator
Generate random version 4 UUIDs.
JWT decoder
Inspect a JSON Web Token’s header and payload locally.
A few things you
can tick off.
- Divide a /24 into right-sized department subnets
- Convert an IP range into firewall CIDR blocks
- Check when a cron job next runs