sipcalc - IPv4/IPv6 subnet calculator

此工具特點是有支援 IPv6, 大部份的 Distro 應該都沒這個套件,
需至 sipcalc 網站 下載 Source 來編譯
以目前 TWNIC 配發的 IPv6 最小區段為例 2001:07FA:0001::/48
就有 2001:07fa:0001:0000:0000:0000:0000:0000 - 2001:07fa:0001:ffff:ffff:ffff:ffff:ffff
共 1208925819614629174706176 個 IP, 已經多到不曉得要用什麼單位來稱呼了

# sipcalc 2001:07FA:0001::/48
-[ipv6 : 2001:07FA:0001::/48] - 0

[IPV6 INFO]
Expanded Address - 2001:07fa:0001:0000:0000:0000:0000:0000
Compressed address - 2001:7fa:1::
Subnet prefix (masked) - 2001:7fa:1:0:0:0:0:0/48
Address ID (masked) - 0:0:0:0:0:0:0:0/48
Prefix address - ffff:ffff:ffff:0:0:0:0:0
Prefix length - 48
Address type - Aggregatable Global Unicast Addresses
Network range - 2001:07fa:0001:0000:0000:0000:0000:0000 -
2001:07fa:0001:ffff:ffff:ffff:ffff:ffff

當然也可計算 IPv4
# sipcalc 192.168.22.1/23
-[ipv4 : 192.168.22.1/23] - 0

[CIDR]
Host address - 192.168.22.1
Host address (decimal) - 3232241153
Host address (hex) - C0A81601
Network address - 192.168.22.0
Network mask - 255.255.254.0
Network mask (bits) - 23
Network mask (hex) - FFFFFE00
Broadcast address - 192.168.23.255
Cisco wildcard - 0.0.1.255
Addresses in network - 512
Network range - 192.168.22.0 - 192.168.23.255
Usable range - 192.168.22.1 - 192.168.23.254

ref. Linux上好用的IP計算工具-sipcalc