Ranges & ports
CIDR maths · overlapping ranges · host counts · port lookup
대역·포트
CIDR 이 어디부터 어디까지인지·몇 대가 들어가는지 세고, 두 대역이 겹치는지 봅니다. 포트 번호도 찾습니다
대역10.0.4.0 – 10.0.7.255
쓸 수 있는 주소10.0.4.1 – 10.0.7.254
주소 수1,024 (실제 1,022대)
마스크255.255.252.0 · 와일드카드 0.0.3.255
갈래사설 대역 (밖에서 못 온다)
셈 끝
Works out where 10.0.0.0/22 starts and ends and how many hosts fit, flags ranges that overlap, and keeps a small port dictionary alongside.
How to use it
- Enter a range (e.g. 10.0.0.0/22)
- Check the first and last address and how many hosts fit
- Enter several lines and overlaps are pointed out
- Look up a port number in the dictionary
Common questions
- Can I not just work it out in my head?
- You will get exactly one digit wrong, and in a firewall rule that one digit leaves a door open or shut.
- Why check for overlaps?
- When two rules overlap, either the later one never fires or the earlier one is far too wide. Both are accidents.
- How complete is the port dictionary?
- It lists only what we actually know — a small dictionary for "what was that number again".
Other tools
Stays on your device What you enter is handled inside your browser only — nothing is stored or sent anywhere.
This tool page states where what you enter goes — see the badge above. All tools · KarmoLab · Who made this · Built with AI. View source