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MtrXTools

Network planner

Merge CIDR blocks, addresses and ranges into the fewest blocks, find which range contains an address, convert between netmasks and Cisco wildcard masks with ready-made ACL snippets, and split an IPv6 prefix into one block per site. Runs in your browser.

Four planning tools

  • Summarise: merge CIDRs, single addresses and start - end ranges into the fewest blocks, plus the single supernet that covers them all. Add ranges to leave out to get "these blocks except those", for example all of IPv4 minus the private ranges.
  • Contains: find which of your ranges contains each address, most specific first.
  • Wildcard and ACL: convert between CIDR, netmask and Cisco wildcard masks, with ready-made Cisco, Juniper, iptables, nftables and cloud firewall snippets.
  • IPv6 plan: give each named site its own /52 to /64 from a prefix, with nibble-alignment warnings that keep reverse DNS simple.

Everything runs in your browser, and the plan is saved in the page URL so you can share it.

Questions

What is a wildcard mask?
The inverse of a netmask, used in Cisco ACLs and OSPF: 0.0.0.255 matches the same addresses as /24. Non-contiguous wildcards are possible and the tool explains what they match.
Why align IPv6 subnets on nibbles?
IPv6 reverse DNS works in 4-bit steps, so prefixes like /48, /52, /56 and /60 each map to a clean zone. Other lengths make delegation awkward.
Can I summarise a list of IPs from a log?
Yes. Paste addresses, CIDRs and ranges in any mix, one per line or comma-separated, and Summarise returns the smallest set of blocks that covers exactly those addresses.

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