SubNetCalc
From Wikipedia, the free encyclopedia
Other namesIPv4/IPv6 Subnet Calculator
Original authorThomas Dreibholz
DevelopersThomas Dreibholz, Simula Research Laboratory, Simula Metropolitan Center for Digital Engineering
Initial releaseJanuary 30, 2009[1]
| SubNetCalc | |
|---|---|
 | |
| Other names | IPv4/IPv6 Subnet Calculator |
| Original author | Thomas Dreibholz |
| Developers | Thomas Dreibholz, Simula Research Laboratory, Simula Metropolitan Center for Digital Engineering |
| Initial release | January 30, 2009[1] |
| Stable release | 2.6.6[2]
/ April 19, 2026 |
| Written in | C++ |
| Operating system | Linux, FreeBSD, MacOS |
| Platform | cross-platform |
| Available in | 4 languages |
List of languages | |
| Type | IP network utility |
| License | GPL-3.0-or-later |
| Website | www |
| Repository | github |
SubNetCalc is an open-source IPv4 and IPv6 subnet address calculator. It is distributed in several major software distributions, including Debian[3], Ubuntu[4], and FreeBSD[5].
SubNetCalc calculates a breakdown of IP network information. It provides:
- Address Analysis: Calculates the network address, broadcast address (IPv4), host address range, and the maximum number of hosts for a given subnet.
- Binary Visualization: Displays addresses in binary format, highlighting the network and host portions.
- Address Classification: Identifies address types and scopes, such as multicast, unique local (ULA), and link-local.
- Unique Local Prefix Generation: Can generate randomly chosen IPv6 Unique Local prefixes according to RFC 4193, using /dev/random or /dev/urandom for entropy.[6]
- Hostname Resolution: Supports resolving hostnames (including Internationalized Domain Names) to IP addresses before performing calculations.
- Geo-Location: Integration with MaxMind GeoIP library to identify the country associated with a given IP address.
Components and Integration
The tool is portable and is maintained as part of the FreeBSD Ports collection and the Debian/Ubuntu package repositories. It also features bash shell-completion support.