security

子网掩码表

子网掩码表及计算方法

host VLSM Subnet Mask subnet
n-2 /
--------------------------------------------------------------------------
n log2 n (32 - log2 n) 256/n
--------------------------------------------------------------------------
8 3 29 255.255.255.248 32
16 4 28 255.255.255.240 16
32 5 27 255.255.255.224 8
64 6 26 255.255.255.192 4
128 7 25 255.255.255.128 2
256 8 24 255.255.255.0 1
512 9 23 255.255.254.0
1024 10 22 255.255.252.0
2048 11 21 255.255.248.0
4096 12 20 255.255.240.0
8192 13 19 255.255.224.0
16384 14 18 255.255.192.0
32768 15 17 255.255.128.0
65536 16 16 255.255.0.0

shorewall

iptables

Firewall (防火墙)

Security (安全)

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