CIDR aggregator
Paste a messy allow-list and get the tidiest set of blocks that covers exactly the same addresses.
One per line, or separated by commas. Comments after # are ignored.
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よくある質問
What does aggregating actually do?
It merges entries that overlap or sit next to each other, then splits each merged run into the fewest CIDR blocks that cover it exactly — no more and no fewer addresses than you started with. Two neighbouring /25 blocks become a single /24.
Why did my two blocks not merge?
A CIDR block has to start on a multiple of its own size. 10.0.0.0/24 and 10.0.1.0/24 merge into 10.0.0.0/23 because the pair is aligned, but 10.0.1.0/24 and 10.0.2.0/24 cannot, even though they touch.
What can I paste in?
CIDR blocks (10.0.0.0/8), bare addresses, an IPv4 netmask (10.0.0.0 255.0.0.0) and dashed ranges (10.0.0.1 - 10.0.0.50). IPv4 and IPv6 can be mixed; they are aggregated separately.