Можно еще использовать вот такую табличку:Адресов Маски
1 /32 255.255.255.255 0xffffffff
2 /31 255.255.255.254 0xfffffffe
4 /30 255.255.255.252 0xfffffffc
8 /29 255.255.255.248 0xfffffff8
16 /28 255.255.255.240 0xfffffff0
32 /27 255.255.255.224 0xffffffe0
64 /26 255.255.255.192 0xffffffc0
128 /25 255.255.255.128 0xffffff80
256 /24 255.255.255.0 0xffffff00
CIDR # IPs netmask Cisco Inverted mask
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/32 1 255.255.255.255 0.0.0.0
/31 2 255.255.255.254 0.0.0.1
/30 4 255.255.255.252 0.0.0.3
/29 8 255.255.255.248 0.0.0.7
/28 16 255.255.255.240 0.0.0.15
/27 32 255.255.255.224 0.0.0.31
/26 64 255.255.255.192 0.0.0.63
/25 128 255.255.255.128 0.0.0.127
/24 256 255.255.255.0 0.0.0.255
/23 2C 255.255.254.0 0.0.1.255
/22 4C 255.255.252.0 0.0.3.255
/21 8C 255.255.248.0 0.0.7.255
/20 16C 255.255.240.0 0.0.15.255
/19 32C 255.255.224.0 0.0.31.255
/18 64C 255.255.192.0 0.0.63.255
/17 128C 255.255.128.0 0.0.127.255
/16 1B 255.255.0.0 0.0.255.255
/15 2B 255.254.0.0 0.1.255.255
/14 4B 255.252.0.0 0.3.255.255
/13 8B 255.248.0.0 0.7.255.255
/12 16B 255.240.0.0 0.15.255.255
/11 32B 255.224.0.0 0.31.255.255
/10 64B 255.192.0.0 0.63.255.255
/9 128B 255.128.0.0 0.127.255.255
/8 1A 255.0.0.0 0.255.255.255
/7 2A 254.0.0.0 1.255.255.255
/6 4A 252.0.0.0 3.255.255.255
/5 8A 248.0.0.0 7.255.255.255
/4 16A 240.0.0.0 15.255.255.255
/3 32A 224.0.0.0 31.255.255.255
/2 64A 192.0.0.0 63.255.255.255
/1 128A 128.0.0.0 127.255.255.255
/0 ALL 0.0.0.0 255.255.255.255
