netmask
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Netmask is a tool for generating terse netmasks in several common formats and converting netmasks from one format to another.
Summary
netmask is an open-source command-line utility, free to use, that generates and converts netmasks between common formats. You run it from the shell, feeding it IP ranges or existing rules, which makes it useful to firewall administrators and network engineers who need to clean up or generalize sloppy rules left behind by a previous netadmin, or reformat them for new firewall software. It sits in the network-utilities space alongside other CIDRCIDRA notation for a block of IP addresses, such as 10.0.0.0/24. The number after the slash says how many leading address bits identify the network. and subnet calculators rather than any single named tool. Under the hood it now uses patricia tree internals, letting it process millions of inputs in seconds rather than hours. The project dates to 2013 and has had four contributors, but there have been no commits in the past year and its most recent release was over a year ago, so it should be treated as stable rather than actively developed.
Netmask is a tool for generating terse netmasks in several common formats and converting netmasks from one format to another.
How netmask helps
Can this pile of overlapping firewall rules be reduced to something shorter?
reads the ranges in, merges and generalizes them through the same tree structure, and prints the smallest equivalent set of rules
What would these subnet rules look like in the format my new firewall expects?
takes existing netmasks or ranges and reprints them in the target notation, without changing which addresses they cover
Which single CIDR block actually covers this scattered list of IP ranges?
folds the list through its internal tree and reports the minimal covering blocks instead of the raw entries
Can a list of millions of addresses be turned into rules without the job taking all day?
walks the whole set through patricia tree internals in a single pass, so processing finishes in seconds instead of hours
Languages
Command line
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Score card
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Shipping velocity releases a month, last 12 months
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Documentation quality release-notes rubric, 0–100
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Breaking-change discipline how rarely a release breaks users, and notice given
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Maintenance risk quiet time against its own cadence, maintainers
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Innovation & surface new capabilities, API and MCP surface
- Community health
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Contributor trend distinct committers, this year against last
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Maintainer concentration bus factor now against a year ago
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Issue backlog trend issues closed per issue opened, 12 months
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Responsiveness median time to a maintainer’s first reply
Nine scores for netmask, each built from the releases, notes and API history this site tracks — and, on Researcher and Business, where it stands among every measured tool in its category and how that has moved.
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Blank means never measured; nothing here is a filled-in zero.
Peer standings are included with Researcher and Business. See how this tool ranks against its competitors, using data we don't publish anywhere else.
See plans →Each score is 0–100 on a published rubric, derived from data this site already shows. A dimension we cannot measure says so — it is never scored 0 and never enters a rank.
How this is scored
- Shipping velocity — releases a month over the last 12 months, on a log scale where 16 a month scores 100. Needs 3 releases in the window.
- Documentation quality — the release-notes rubric published on the analytics page, unchanged.
- Breaking-change discipline — the share of releases carrying a breaking change (none scores 100, half or more scores 0). Only projects that label breaking changes are measured: a clean record cannot be told from an unlabelled one.
- Maintenance risk — quiet time measured against the tool's own release cadence (quiet longer than 90 days and three typical gaps scores 0), plus the number of active maintainers and whether contributors are growing, where known. Higher is lower risk.
- Innovation & surface — new capabilities in the feature ledger this year, API and MCP operations added, and the share of commits that are features: the mean of whichever we hold.
- Community health (open-source tools only) — each is a direction, not a size: contributors this year against last, the bus factor now against a year ago, and issues closed per issue opened, where steady scores 50, doubled 100 and halved 0; plus the median time to a maintainer's first reply (an hour scores about 100, a month or more 0). A commercial card has no repository and carries none of the four.
- Documented delivery (commercial tools) — when a vendor's documented new capabilities have slowed against its own baseline, that counts against the overall standing as heavily as two low dimensions. Steady delivery, or too little history to judge, leaves the standing alone; it is never a sixth score.
- Open-source tools are scored on repository signals; commercial tools on their published changelog. Ranks compare tools within one category and one profile and need at least five measured peers; the overall standing needs three ranked dimensions. Best-in-breed or consolidator is a shape, not a quality, and is never scored.
Release-note detail over time
See how much detail netmask puts in its release notes, quarter by quarter, and compare it with tracked tools in the same category. This history uses up to ten retained, reviewed notes per tool; sparse or blank older quarters may reflect that limit.
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Releases
2 entries
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- July 20252
Project health
Issue, contributor and maintainer activity in tlby/netmask, 2023-10 – 2026-09, as of 2026-09-25. Twelve-month figures first; the trend lines run the whole window.
- Contributors 0 −1 vs prior 12 months
- Maintainers 0 +0 joined · −0 left, last 12 months
- Bus factor 0 committers behind half the commits
- Community-filed not measured of issues opened, last 12 months
- Median time to close not measured issues closed, last 12 months
- Open backlog 1 of 6 issues ever filed
- Issues opened / month 0 · 0 communitymaintainers
- Open backlog 1
- Contributors / month 0
- Commits / month 0
- Stars 40
Counts from the project's public repository and git history; no individuals are identified. Maintainers are the committers covering 80% of the last year's commits. how we measure this
Libraries its release ships
What its latest release locks, checked against known advisories.None of its release's images build from a lockfile we can read.
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