SubnetTools.psm1
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function Find-ValidSubnet { <# .SYNOPSIS Takes an IPv4 network address and creates subnets based on hosts and networks needed. .DESCRIPTION This command calculates all possible subnet masks that will accommodate the required subnets and hosts/subnet. Once the masks are found it will then produce all of the possible subnet ranges per subnet mask. It also has the option to show only the smallest subnets in regard to hosts/subnet (largest CIDR mask). These is also an option to show all subnets and this is very useful when trying to plan for VLSM subnets. This is a basic example: Find-ValidSubnet -CIDRSubnetAddress 172.16.0.0/16 -SubnetsRequired 4 -HostsPerSubnetRequired 6000 | Format-Table -GroupBy Mask Mask: 18 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 18 172.16.0.0 172.16.0.1 172.16.63.254 172.16.63.255 16382 1 4 18 172.16.64.0 172.16.64.1 172.16.127.254 172.16.127.255 16382 2 4 18 172.16.128.0 172.16.128.1 172.16.191.254 172.16.191.255 16382 3 4 18 172.16.192.0 172.16.192.1 172.16.255.254 172.16.255.255 16382 4 4 Mask: 19 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 19 172.16.0.0 172.16.0.1 172.16.31.254 172.16.31.255 8190 1 8 19 172.16.32.0 172.16.32.1 172.16.63.254 172.16.63.255 8190 2 8 19 172.16.64.0 172.16.64.1 172.16.95.254 172.16.95.255 8190 3 8 19 172.16.96.0 172.16.96.1 172.16.127.254 172.16.127.255 8190 4 8 19 172.16.128.0 172.16.128.1 172.16.159.254 172.16.159.255 8190 5 8 19 172.16.160.0 172.16.160.1 172.16.191.254 172.16.191.255 8190 6 8 19 172.16.192.0 172.16.192.1 172.16.223.254 172.16.223.255 8190 7 8 19 172.16.224.0 172.16.224.1 172.16.255.254 172.16.255.255 8190 8 8 It will also make sure the original network address is a network address and if it is not it will AND the given address with the oiginal mask to find the network address. It is suggested that the output be formated into a table with a -groupby Mask parameter. .EXAMPLE Find-ValidSubnet -CIDRSubnetAddress 172.16.0.0/16 -SubnetsRequired 4 -HostsPerSubnetRequired 4000 | Format-Table -GroupBy Mask Using the 172.16.0.0/16 network as a base this will find all subnet masks that will allow for a minimum of 4 subnets, while still allowing 4000 hosts per subnet. The subnets willl be listed for each subnet mask discovered Mask: 18 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 18 172.16.0.0 172.16.0.1 172.16.63.254 172.16.63.255 16382 1 4 18 172.16.64.0 172.16.64.1 172.16.127.254 172.16.127.255 16382 2 4 18 172.16.128.0 172.16.128.1 172.16.191.254 172.16.191.255 16382 3 4 18 172.16.192.0 172.16.192.1 172.16.255.254 172.16.255.255 16382 4 4 Mask: 19 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 19 172.16.0.0 172.16.0.1 172.16.31.254 172.16.31.255 8190 1 8 19 172.16.32.0 172.16.32.1 172.16.63.254 172.16.63.255 8190 2 8 19 172.16.64.0 172.16.64.1 172.16.95.254 172.16.95.255 8190 3 8 19 172.16.96.0 172.16.96.1 172.16.127.254 172.16.127.255 8190 4 8 19 172.16.128.0 172.16.128.1 172.16.159.254 172.16.159.255 8190 5 8 19 172.16.160.0 172.16.160.1 172.16.191.254 172.16.191.255 8190 6 8 19 172.16.192.0 172.16.192.1 172.16.223.254 172.16.223.255 8190 7 8 19 172.16.224.0 172.16.224.1 172.16.255.254 172.16.255.255 8190 8 8 Mask: 20 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 20 172.16.0.0 172.16.0.1 172.16.15.254 172.16.15.255 4094 1 16 20 172.16.16.0 172.16.16.1 172.16.31.254 172.16.31.255 4094 2 16 20 172.16.32.0 172.16.32.1 172.16.47.254 172.16.47.255 4094 3 16 20 172.16.48.0 172.16.48.1 172.16.63.254 172.16.63.255 4094 4 16 20 172.16.64.0 172.16.64.1 172.16.79.254 172.16.79.255 4094 5 16 20 172.16.80.0 172.16.80.1 172.16.95.254 172.16.95.255 4094 6 16 20 172.16.96.0 172.16.96.1 172.16.111.254 172.16.111.255 4094 7 16 20 172.16.112.0 172.16.112.1 172.16.127.254 172.16.127.255 4094 8 16 20 172.16.128.0 172.16.128.1 172.16.143.254 172.16.143.255 4094 9 16 20 172.16.144.0 172.16.144.1 172.16.159.254 172.16.159.255 4094 10 16 20 172.16.160.0 172.16.160.1 172.16.175.254 172.16.175.255 4094 11 16 20 172.16.176.0 172.16.176.1 172.16.191.254 172.16.191.255 4094 12 16 20 172.16.192.0 172.16.192.1 172.16.207.254 172.16.207.255 4094 13 16 20 172.16.208.0 172.16.208.1 172.16.223.254 172.16.223.255 4094 14 16 20 172.16.224.0 172.16.224.1 172.16.239.254 172.16.239.255 4094 15 16 20 172.16.240.0 172.16.240.1 172.16.255.254 172.16.255.255 4094 16 16 .EXAMPLE Find-ValidSubnet -CIDRSubnetAddress 192.168.20.0/24 -AllSubnets | Format-Table -GroupBy Mask Using the 192.168.20.0/24 network as a base this will find all subnets that are possible, this is very handy when trying to plan VLSM subnets. Mask: 24 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 24 192.168.20.0 192.168.20.1 192.168.20.254 192.168.20.255 254 1 1 Mask: 25 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 25 192.168.20.0 192.168.20.1 192.168.20.126 192.168.20.127 126 1 2 25 192.168.20.128 192.168.20.129 192.168.20.254 192.168.20.255 126 2 2 Mask: 26 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 26 192.168.20.0 192.168.20.1 192.168.20.62 192.168.20.63 62 1 4 26 192.168.20.64 192.168.20.65 192.168.20.126 192.168.20.127 62 2 4 26 192.168.20.128 192.168.20.129 192.168.20.190 192.168.20.191 62 3 4 26 192.168.20.192 192.168.20.193 192.168.20.254 192.168.20.255 62 4 4 Mask: 27 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 27 192.168.20.0 192.168.20.1 192.168.20.30 192.168.20.31 30 1 8 27 192.168.20.32 192.168.20.33 192.168.20.62 192.168.20.63 30 2 8 27 192.168.20.64 192.168.20.65 192.168.20.94 192.168.20.95 30 3 8 27 192.168.20.96 192.168.20.97 192.168.20.126 192.168.20.127 30 4 8 27 192.168.20.128 192.168.20.129 192.168.20.158 192.168.20.159 30 5 8 27 192.168.20.160 192.168.20.161 192.168.20.190 192.168.20.191 30 6 8 27 192.168.20.192 192.168.20.193 192.168.20.222 192.168.20.223 30 7 8 27 192.168.20.224 192.168.20.225 192.168.20.254 192.168.20.255 30 8 8 Mask: 28 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 28 192.168.20.0 192.168.20.1 192.168.20.14 192.168.20.15 14 1 16 28 192.168.20.16 192.168.20.17 192.168.20.30 192.168.20.31 14 2 16 28 192.168.20.32 192.168.20.33 192.168.20.46 192.168.20.47 14 3 16 28 192.168.20.48 192.168.20.49 192.168.20.62 192.168.20.63 14 4 16 28 192.168.20.64 192.168.20.65 192.168.20.78 192.168.20.79 14 5 16 28 192.168.20.80 192.168.20.81 192.168.20.94 192.168.20.95 14 6 16 28 192.168.20.96 192.168.20.97 192.168.20.110 192.168.20.111 14 7 16 28 192.168.20.112 192.168.20.113 192.168.20.126 192.168.20.127 14 8 16 28 192.168.20.128 192.168.20.129 192.168.20.142 192.168.20.143 14 9 16 28 192.168.20.144 192.168.20.145 192.168.20.158 192.168.20.159 14 10 16 28 192.168.20.160 192.168.20.161 192.168.20.174 192.168.20.175 14 11 16 28 192.168.20.176 192.168.20.177 192.168.20.190 192.168.20.191 14 12 16 28 192.168.20.192 192.168.20.193 192.168.20.206 192.168.20.207 14 13 16 28 192.168.20.208 192.168.20.209 192.168.20.222 192.168.20.223 14 14 16 28 192.168.20.224 192.168.20.225 192.168.20.238 192.168.20.239 14 15 16 28 192.168.20.240 192.168.20.241 192.168.20.254 192.168.20.255 14 16 16 Mask: 29 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 29 192.168.20.0 192.168.20.1 192.168.20.6 192.168.20.7 6 1 32 29 192.168.20.8 192.168.20.9 192.168.20.14 192.168.20.15 6 2 32 29 192.168.20.16 192.168.20.17 192.168.20.22 192.168.20.23 6 3 32 29 192.168.20.24 192.168.20.25 192.168.20.30 192.168.20.31 6 4 32 29 192.168.20.32 192.168.20.33 192.168.20.38 192.168.20.39 6 5 32 29 192.168.20.40 192.168.20.41 192.168.20.46 192.168.20.47 6 6 32 29 192.168.20.48 192.168.20.49 192.168.20.54 192.168.20.55 6 7 32 29 192.168.20.56 192.168.20.57 192.168.20.62 192.168.20.63 6 8 32 29 192.168.20.64 192.168.20.65 192.168.20.70 192.168.20.71 6 9 32 29 192.168.20.72 192.168.20.73 192.168.20.78 192.168.20.79 6 10 32 29 192.168.20.80 192.168.20.81 192.168.20.86 192.168.20.87 6 11 32 29 192.168.20.88 192.168.20.89 192.168.20.94 192.168.20.95 6 12 32 29 192.168.20.96 192.168.20.97 192.168.20.102 192.168.20.103 6 13 32 29 192.168.20.104 192.168.20.105 192.168.20.110 192.168.20.111 6 14 32 29 192.168.20.112 192.168.20.113 192.168.20.118 192.168.20.119 6 15 32 29 192.168.20.120 192.168.20.121 192.168.20.126 192.168.20.127 6 16 32 29 192.168.20.128 192.168.20.129 192.168.20.134 192.168.20.135 6 17 32 29 192.168.20.136 192.168.20.137 192.168.20.142 192.168.20.143 6 18 32 29 192.168.20.144 192.168.20.145 192.168.20.150 192.168.20.151 6 19 32 29 192.168.20.152 192.168.20.153 192.168.20.158 192.168.20.159 6 20 32 29 192.168.20.160 192.168.20.161 192.168.20.166 192.168.20.167 6 21 32 29 192.168.20.168 192.168.20.169 192.168.20.174 192.168.20.175 6 22 32 29 192.168.20.176 192.168.20.177 192.168.20.182 192.168.20.183 6 23 32 29 192.168.20.184 192.168.20.185 192.168.20.190 192.168.20.191 6 24 32 29 192.168.20.192 192.168.20.193 192.168.20.198 192.168.20.199 6 25 32 29 192.168.20.200 192.168.20.201 192.168.20.206 192.168.20.207 6 26 32 29 192.168.20.208 192.168.20.209 192.168.20.214 192.168.20.215 6 27 32 29 192.168.20.216 192.168.20.217 192.168.20.222 192.168.20.223 6 28 32 29 192.168.20.224 192.168.20.225 192.168.20.230 192.168.20.231 6 29 32 29 192.168.20.232 192.168.20.233 192.168.20.238 192.168.20.239 6 30 32 29 192.168.20.240 192.168.20.241 192.168.20.246 192.168.20.247 6 31 32 29 192.168.20.248 192.168.20.249 192.168.20.254 192.168.20.255 6 32 32 Mask: 30 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 30 192.168.20.0 192.168.20.1 192.168.20.2 192.168.20.3 2 1 64 30 192.168.20.4 192.168.20.5 192.168.20.6 192.168.20.7 2 2 64 30 192.168.20.8 192.168.20.9 192.168.20.10 192.168.20.11 2 3 64 30 192.168.20.12 192.168.20.13 192.168.20.14 192.168.20.15 2 4 64 30 192.168.20.16 192.168.20.17 192.168.20.18 192.168.20.19 2 5 64 30 192.168.20.20 192.168.20.21 192.168.20.22 192.168.20.23 2 6 64 30 192.168.20.24 192.168.20.25 192.168.20.26 192.168.20.27 2 7 64 30 192.168.20.28 192.168.20.29 192.168.20.30 192.168.20.31 2 8 64 30 192.168.20.32 192.168.20.33 192.168.20.34 192.168.20.35 2 9 64 30 192.168.20.36 192.168.20.37 192.168.20.38 192.168.20.39 2 10 64 30 192.168.20.40 192.168.20.41 192.168.20.42 192.168.20.43 2 11 64 30 192.168.20.44 192.168.20.45 192.168.20.46 192.168.20.47 2 12 64 30 192.168.20.48 192.168.20.49 192.168.20.50 192.168.20.51 2 13 64 30 192.168.20.52 192.168.20.53 192.168.20.54 192.168.20.55 2 14 64 30 192.168.20.56 192.168.20.57 192.168.20.58 192.168.20.59 2 15 64 30 192.168.20.60 192.168.20.61 192.168.20.62 192.168.20.63 2 16 64 30 192.168.20.64 192.168.20.65 192.168.20.66 192.168.20.67 2 17 64 30 192.168.20.68 192.168.20.69 192.168.20.70 192.168.20.71 2 18 64 30 192.168.20.72 192.168.20.73 192.168.20.74 192.168.20.75 2 19 64 30 192.168.20.76 192.168.20.77 192.168.20.78 192.168.20.79 2 20 64 30 192.168.20.80 192.168.20.81 192.168.20.82 192.168.20.83 2 21 64 30 192.168.20.84 192.168.20.85 192.168.20.86 192.168.20.87 2 22 64 30 192.168.20.88 192.168.20.89 192.168.20.90 192.168.20.91 2 23 64 30 192.168.20.92 192.168.20.93 192.168.20.94 192.168.20.95 2 24 64 30 192.168.20.96 192.168.20.97 192.168.20.98 192.168.20.99 2 25 64 30 192.168.20.100 192.168.20.101 192.168.20.102 192.168.20.103 2 26 64 30 192.168.20.104 192.168.20.105 192.168.20.106 192.168.20.107 2 27 64 30 192.168.20.108 192.168.20.109 192.168.20.110 192.168.20.111 2 28 64 30 192.168.20.112 192.168.20.113 192.168.20.114 192.168.20.115 2 29 64 30 192.168.20.116 192.168.20.117 192.168.20.118 192.168.20.119 2 30 64 30 192.168.20.120 192.168.20.121 192.168.20.122 192.168.20.123 2 31 64 30 192.168.20.124 192.168.20.125 192.168.20.126 192.168.20.127 2 32 64 30 192.168.20.128 192.168.20.129 192.168.20.130 192.168.20.131 2 33 64 30 192.168.20.132 192.168.20.133 192.168.20.134 192.168.20.135 2 34 64 30 192.168.20.136 192.168.20.137 192.168.20.138 192.168.20.139 2 35 64 30 192.168.20.140 192.168.20.141 192.168.20.142 192.168.20.143 2 36 64 30 192.168.20.144 192.168.20.145 192.168.20.146 192.168.20.147 2 37 64 30 192.168.20.148 192.168.20.149 192.168.20.150 192.168.20.151 2 38 64 30 192.168.20.152 192.168.20.153 192.168.20.154 192.168.20.155 2 39 64 30 192.168.20.156 192.168.20.157 192.168.20.158 192.168.20.159 2 40 64 30 192.168.20.160 192.168.20.161 192.168.20.162 192.168.20.163 2 41 64 30 192.168.20.164 192.168.20.165 192.168.20.166 192.168.20.167 2 42 64 30 192.168.20.168 192.168.20.169 192.168.20.170 192.168.20.171 2 43 64 30 192.168.20.172 192.168.20.173 192.168.20.174 192.168.20.175 2 44 64 30 192.168.20.176 192.168.20.177 192.168.20.178 192.168.20.179 2 45 64 30 192.168.20.180 192.168.20.181 192.168.20.182 192.168.20.183 2 46 64 30 192.168.20.184 192.168.20.185 192.168.20.186 192.168.20.187 2 47 64 30 192.168.20.188 192.168.20.189 192.168.20.190 192.168.20.191 2 48 64 30 192.168.20.192 192.168.20.193 192.168.20.194 192.168.20.195 2 49 64 30 192.168.20.196 192.168.20.197 192.168.20.198 192.168.20.199 2 50 64 30 192.168.20.200 192.168.20.201 192.168.20.202 192.168.20.203 2 51 64 30 192.168.20.204 192.168.20.205 192.168.20.206 192.168.20.207 2 52 64 30 192.168.20.208 192.168.20.209 192.168.20.210 192.168.20.211 2 53 64 30 192.168.20.212 192.168.20.213 192.168.20.214 192.168.20.215 2 54 64 30 192.168.20.216 192.168.20.217 192.168.20.218 192.168.20.219 2 55 64 30 192.168.20.220 192.168.20.221 192.168.20.222 192.168.20.223 2 56 64 30 192.168.20.224 192.168.20.225 192.168.20.226 192.168.20.227 2 57 64 30 192.168.20.228 192.168.20.229 192.168.20.230 192.168.20.231 2 58 64 30 192.168.20.232 192.168.20.233 192.168.20.234 192.168.20.235 2 59 64 30 192.168.20.236 192.168.20.237 192.168.20.238 192.168.20.239 2 60 64 30 192.168.20.240 192.168.20.241 192.168.20.242 192.168.20.243 2 61 64 30 192.168.20.244 192.168.20.245 192.168.20.246 192.168.20.247 2 62 64 30 192.168.20.248 192.168.20.249 192.168.20.250 192.168.20.251 2 63 64 30 192.168.20.252 192.168.20.253 192.168.20.254 192.168.20.255 2 64 64 .Example Find-ValidSubnet -AzureSubnet -CIDRSubnetAddress 200.107.30.0/24 -HostsPerSubnetRequired 12 -SubnetsRequired 4 | ft -GroupBy mask This will calculate the required subnet ranges taking into account that Azure reserves 5 addresses by convention instead of the 2 for a standard subnet: for a /24 subnet Azure reserves the folloing: x.x.x.x.0 Subnet ID x.x.x.x.1 Default gateway x.x.x.x.2 & x.x.x.x.3 DNS x.x.x.x.255 Broadcast Mask: 26 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 26 200.107.30.0 200.107.30.4 200.107.30.62 200.107.30.63 59 1 4 26 200.107.30.64 200.107.30.68 200.107.30.126 200.107.30.127 59 2 4 26 200.107.30.128 200.107.30.132 200.107.30.190 200.107.30.191 59 3 4 26 200.107.30.192 200.107.30.196 200.107.30.254 200.107.30.255 59 4 4 Mask: 27 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet Subnet TotalSubnets ---- -------- ------------ ----------- ----------- -------------- ------ ------------ 27 200.107.30.0 200.107.30.4 200.107.30.30 200.107.30.31 27 1 8 27 200.107.30.32 200.107.30.36 200.107.30.62 200.107.30.63 27 2 8 27 200.107.30.64 200.107.30.68 200.107.30.94 200.107.30.95 27 3 8 27 200.107.30.96 200.107.30.100 200.107.30.126 200.107.30.127 27 4 8 27 200.107.30.128 200.107.30.132 200.107.30.158 200.107.30.159 27 5 8 27 200.107.30.160 200.107.30.164 200.107.30.190 200.107.30.191 27 6 8 27 200.107.30.192 200.107.30.196 200.107.30.222 200.107.30.223 27 7 8 27 200.107.30.224 200.107.30.228 200.107.30.254 200.107.30.255 27 8 8 .EXAMPLE Find-ValidSubnet -CIDRSubnetAddress 122.1.1.0/24 -VLSMSubnetHostNumbers 90,20,10,2,2 | Format-Table This would create multiple subnets from the Class C address to allow the following number of hosts to be accommodated by seperate subnets of varying sizes. Subnet Host Count ------ ---------- Subnet1 90 Subnet2 20 Subnet3 10 Subnet4 2 Subnet5 2 Mask SubnetID FirstValidIP LastValidIP BroadcastIP HostsPerSubnet ---- -------- ------------ ----------- ----------- -------------- 25 122.1.1.0 122.1.1.1 122.1.1.126 122.1.1.127 126 27 122.1.1.128 122.1.1.129 122.1.1.158 122.1.1.159 30 28 122.1.1.160 122.1.1.161 122.1.1.174 122.1.1.175 14 30 122.1.1.176 122.1.1.177 122.1.1.178 122.1.1.179 2 30 122.1.1.180 122.1.1.181 122.1.1.182 122.1.1.183 2 .PARAMETER CIDRSubnetAddress This parameter requires the network address to be entered with the CIDR mask as well. In this format 172.16.0.0/16 .PARAMETER SubnetsRequired This parameter declares how many subnets the CIDR network will need to be broken into as a minimum. Because this is a minimum, this command will also look for all valid subnets as long as it still allows for the number of hosts per subnet, -HostsPerSubnetRequired parameter value. .PARAMETER HostsPerSubnetRequired This parameter dictates the minimum amount of hosts that are required per subnet. .PARAMETER SmallestSubnetMask This parameter only shows the smallest subnets, those with the biggest subnet mask value. .PARAMETER LargestSubnetMask This parameter only shows the largest subnets, those with the smallest subnet mask value. .PARAMETER AllSubnets This parameter show all possible subnets. .PARAMETER AzureSubnet This parameter changes the ranges of each subnet removing 5 host IDs as Azure uses x.x.x.1 for Default Gateway, x.x.x.2 & x.x.x.3 for DNS mapping. .PARAMETER VLSMSubnetHostNumbers This is the list of hosts per subnet to create VLSM subnets from .NOTES General notes Created by: Brent Denny Created on: 09 Mar 2021 Last Modified: 14 Dec 2021 Change Log: 14-Dec-2022 I noticed that when run on Linux OS the output for the number of hosts and subnets was of type [double], however these should be [int]. Modifying this to present the data correctly. #> [cmdletbinding(DefaultParameterSetName='Default',PositionalBinding=$false)] Param ( [Parameter(ParameterSetName='VLSM')] [Parameter(ParameterSetName='AllSubnets')] [Parameter(ParameterSetName='Subnet')] [switch]$AzureSubnet, [Parameter(Mandatory=$true,ParameterSetName='AllSubnets')] [Parameter(Mandatory=$true,ParameterSetName='Subnet')] [Parameter(ParameterSetName='VLSM')] [string]$CIDRSubnetAddress, [Parameter(Mandatory=$true,ParameterSetName='Subnet')] [int]$SubnetsRequired, [Parameter(Mandatory=$true,ParameterSetName='Subnet')] [int]$HostsPerSubnetRequired, [Parameter(ParameterSetName='Subnet')] [switch]$SmallestSubnetMask, [Parameter(ParameterSetName='Subnet')] [switch]$LargestSubnetMask, [Parameter(ParameterSetName='AllSubnets')] [switch]$AllSubnets, [Parameter(ParameterSetName='VLSM')] [int[]]$VLSMSubnetHostNumbers ) function ConvertTo-IPAddressObject { [cmdletbinding(DefaultParameterSetName='Default')] Param ( [int]$BitCount, [Parameter(ParameterSetName='IPAddress')] [string]$IPAddress, [Parameter(ParameterSetName='DecAddress')] [int64]$DecAddress ) # this function will take a bit count, IPaddress or decimal address, and # convert any of them into an object that contains a forward and reverse versions # of the IPAddresses and their decimal values if ($PSCmdlet.ParameterSetName -eq 'Default') { $BinaryString = '1' * $BitCount + '0' * (32 - $BitCount) $IPObj = [ipaddress]([convert]::ToInt64($BinaryString,2)) $FwdAddrIPObj = [ipaddress]($IPObj.IPAddressToString -replace '^(\d+)\.(\d+)\.(\d+)\.(\d+)$','$4.$3.$2.$1') $RevAddrIPObj = $IPObj } elseif ($PSCmdlet.ParameterSetName -eq 'IPAddress') { $FwdAddrIPObj = [ipaddress]$IPAddress $RevAddrIPObj = [ipaddress]($IPAddress -replace '^(\d+)\.(\d+)\.(\d+)\.(\d+)$','$4.$3.$2.$1') } elseif ($PSCmdlet.ParameterSetName -eq 'DecAddress') { $IPObj = [ipaddress]$DecAddress $FwdAddrIPObj = [ipaddress]($IPObj.IPAddressToString -replace '^(\d+)\.(\d+)\.(\d+)\.(\d+)$','$4.$3.$2.$1') $RevAddrIPObj = $IPObj } $ObjProp = [ordered]@{ FwdAddrIP = $FwdAddrIPObj.IPAddressToString FwdAddrDec = $FwdAddrIPObj.Address RevAddrIP = $RevAddrIPObj.IPAddressToString RevAddrDec = $RevAddrIPObj.Address } New-object -TypeName psobject -Property $ObjProp } function Find-IPSubnetRange { [cmdletbinding()] Param ( [string]$IPAddress, [int]$InitialMask, [int]$SubnetMask, [switch]$Azure ) # This function will find all of the valid subnets for a subnetted mask, and list the following # Mask,Subnet,FirstValidIP,LastValidIP,BroadcastIP,HostsPerSubnet and Subnet Number $MaxSubnetIndex = [math]::Pow(2,$SubnetMask - $InitialMask) - 1 $JumpValue = [math]::Pow(2,8-$SubnetMask % 8) $JumpIndex = [math]::Truncate($SubnetMask / 8) if ($JumpValue -eq 256) { $JumpValue = 1 $JumpIndex = $JumpIndex - 1 } if ($Azure -eq $true) {$AzureReserved = 3} else {$AzureReserved = 0} [int[]]$JumpIPArray = 0,0,0,0 $JumpIPArray[$JumpIndex] = $JumpValue $JumpIPAddr = $JumpIPArray -join '.' $JumpIPAddressSet = ConvertTo-IPAddressObject -IPAddress $JumpIPAddr $IPAddressSet = ConvertTo-IPAddressObject -IPAddress $IPAddress foreach ($SubnetIndex in (0..$MaxSubnetIndex)) { # The ...RevDec refers to the IP addresses decimal value, it 'turns out' that the # [IPAddress] object reverses the decimal value of the IP, so by reversing the # reverse we get the actual decimal value. This is why you see this everywhere # within this function $ThisSubnetRevDec = $IPAddressSet.RevAddrDec + ($SubnetIndex * $JumpIPAddressSet.RevAddrDec) $ThisSubnetSet = ConvertTo-IPAddressObject -DecAddress $ThisSubnetRevDec $FirstValidRevDec = $ThisSubnetRevDec + 1 + $AzureReserved $LastValidRevDec = $ThisSubnetRevDec + $JumpIPAddressSet.RevAddrDec - 2 $BroadCastRevDec = $ThisSubnetRevDec + $JumpIPAddressSet.RevAddrDec - 1 $FirstValidSet = ConvertTo-IPAddressObject -DecAddress $FirstValidRevDec $LastValidSet = ConvertTo-IPAddressObject -DecAddress $LastValidRevDec $BroadCastSet = ConvertTo-IPAddressObject -DecAddress $BroadCastRevDec $ObjProp = [ordered]@{ Mask = $SubnetMask SubnetID = $ThisSubnetSet.FwdAddrIP FirstValidIP = $FirstValidSet.FwdAddrIP LastValidIP = $LastValidSet.FwdAddrIP BroadcastIP = $BroadCastSet.FwdAddrIP HostsPerSubnet = ([math]::Pow(2,32 -$SubnetMask) - (2 + $AzureReserved)) -as [int] Subnet = $SubnetIndex + 1 TotalSubnets = ($MaxSubnetIndex + 1) -as [int] } New-Object -TypeName psobject -Property $ObjProp } } ## MAIN Function BODY if ($AllSubnets -eq $true) { $SubnetsRequired = 1 $HostsPerSubnetRequired = 1 } $BadEntry = $false if ($PSCmdlet.ParameterSetName -in ('AllSubnets','VLSM') -and $CIDRSubnetAddress -eq '') {$BadEntry = $true} elseif ($CIDRSubnetAddress -eq '' -and ($SubnetsRequired -eq 0 -or $SubnetsRequired -gt 4194304 -or $HostsPerSubnetRequired -gt 16777214 -or $VLSMSubnetHostNumbers.count -eq 0)) {$BadEntry = $true} if ($BadEntry -eq $true) { Write-Warning "Invalid or incomplete information was entered for this command, Please use Get-Help -Full $($MyInvocation.InvocationName) to learn more about how to run this command" break } if ($PSCmdlet.ParameterSetName -eq 'VLSM') { $VLSMSubnetHostNumbers = $VLSMSubnetHostNumbers | Sort-Object -Descending $SubnetsRequired = 1 $HostsPerSubnetRequired = 1 } $CIDRParts = $CIDRSubnetAddress -split '\/' $SubnetID = $CIDRParts[0] -as [string] $InitialMask = $CIDRParts[1] -as [int] if ($AzureSubnet -eq $true) {$Reserved = 5} # Azure reserves 5 hostids for internal and netork reasons else {$Reserved = 2} # This is the subnetID and BroadcastID $HostBitsRequired = [math]::Ceiling([math]::Log($HostsPerSubnetRequired+$Reserved)/[math]::log(2)) # +2 to cater for NetworkId and BroadcastID addresses $NetworkBitsRequired = [math]::Ceiling([math]::Log($SubnetsRequired)/[math]::log(2)) $TotalBitsRequired = $InitialMask + $HostBitsRequired + $NetworkBitsRequired # Make sure the given IP addres is an IP Address if ($CIDRSubnetAddress -notmatch '^([1-9]|[1-9][0-9]|1[01][0-9]|12[0-6]|12[89]|1[3-9][0-9]|2[0-2][0-3])(\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}\/([2-9]|[12][0-9]|30)$') { write-warning "$CIDRSubnetAddress - is not a valid address please enter the address and mask, for example: 164.12.0.0/16" break } elseif ($TotalBitsRequired -gt 32) { Write-Warning "The solution you requested requires $TotalBitsRequired bits in the address, we only have 32 bits in IPv4" break } else { $MaskSet = ConvertTo-IPAddressObject -BitCount $InitialMask $SubnetSet = ConvertTo-IPAddressObject -IPAddress $SubnetID # ANDing the Network address with original mask to produce a real network address # this is just in case an address that was entered was a host address and # not the network address. $NetBinAndMaskDec = $SubnetSet.RevAddrDec -band $MaskSet.RevAddrDec # Fixed IP uses ANDing to make sure the subnet address is the actual address of the subnet and not a host address # the subnet. $ActualNetworkAddrSet = ConvertTo-IPAddressObject -DecAddress $NetBinAndMaskDec $SubnetingBitsArray = 0..(32 - $TotalBitsRequired ) | ForEach-Object { # Finding how many subnet bits are required for the number of subnets requested [math]::Ceiling([math]::Log($SubnetsRequired)/[math]::log(2)) + $_ + $InitialMask } $SubnetResults = foreach ($SubnettedBits in $SubnetingBitsArray) { # Go find the valid subnet ranges per valid subnet mask if ($AzureSubnet -eq $true) { Find-IPSubnetRange -IPAddress $ActualNetworkAddrSet.FwdAddrIP -InitialMask $InitialMask -SubnetMask $SubnettedBits -Azure | Where-Object {$_.HostsPerSubnet -ge $HostsPerSubnetRequired -and $_.TotalSubnets -ge $SubnetsRequired} } else { Find-IPSubnetRange -IPAddress $ActualNetworkAddrSet.FwdAddrIP -InitialMask $InitialMask -SubnetMask $SubnettedBits | Where-Object {$_.HostsPerSubnet -ge $HostsPerSubnetRequired -and $_.TotalSubnets -ge $SubnetsRequired} } } if ($PSCmdlet.ParameterSetName -ne 'VLSM') { if ($SmallestSubnets -eq $true) {$SubnetResults | Where-Object {$_.Mask -eq $SubnetResults[-1].Mask}} if ($LargestSubnets -eq $true) {$SubnetResults | Where-Object {$_.Mask -eq $SubnetResults[0].Mask}} if ($SmallestSubnets -ne $true -and $LargestSubnets -ne $true) {$SubnetResults} } else { [System.Collections.ArrayList]$ArrayListSubnets = $SubnetResults Remove-Variable -Name Subnet -ErrorAction SilentlyContinue $VLSMSubnets = @() foreach ($HostCount in $VLSMSubnetHostNumbers) { $TotalHosts = $HostCount + 2 $VLSMHostBits = [math]::Ceiling([math]::Log($TotalHosts)/[math]::Log(2)) $VlSMMask = 32 - $VLSMHostBits if ($Subnet) { $AddOneToBcIPLastOctet = (($Subnet.BroadcastIP -split '\.')[3] -as [int]) + 1 Write-Verbose " add one $AddOneToBcIPLastOctet" Write-Verbose "subnet $Subnet" $NextSubnetIP = (($Subnet.SubnetID -replace '^(\d{1,3}\.\d{1,3}\.\d{1,3}\.).+$','$1') + $AddOneToBcIPLastOctet ) -join '.' Write-Verbose "Next subnet $NextSubnetIP" $Subnet = $ArrayListSubnets | Where-Object {$_.Mask -eq $VlSMMask -and $_.SubnetID -eq $NextSubnetIP} } else { $Subnet = $ArrayListSubnets | Where-Object {$_.Mask -eq $VlSMMask} | Select-Object -First 1 } $VLSMSubnets += $Subnet | Select-Object -Property * -ExcludeProperty Subnet,TotalSubnets } if ($VLSMSubnets.Count -eq $VLSMSubnetHostNumbers.count) {$VLSMSubnets} else {Write-Warning "This address space is not big enough to accommodate the subnets required"} } } } function Show-IPFwdAndRev { <# .SYNOPSIS Given an IP address in one of different forms it shows forward and reverse IP address information .DESCRIPTION You can enter the IP address in one of five forms: Reverse IP Address Forward IP Address Reverse Decimal IP Address Forward Decimal IP Address CIDR Mask integer .EXAMPLE Show-IPFwdAndRev -FwdIPAddress 192.168.20.13 This will show the following information: ForwardIP : 192.168.20.13 FwdDecIP : 3232240653 FwdBinary : 11000000101010000001010000001101 FwdBinaryGroups : 11000000 10101000 00010100 00001101 ReverseIP : 13.20.168.192 RevDecIP : 219457728 RevBinary : 00001101000101001010100011000000 FwdBinaryGroups : 00001101 00010100 10101000 11000000 .PARAMETER RevIPAddress This will take an IP that has been reversed and show all forms of that IP address .PARAMETER FwdIPAddress This will take an IP and show all forms of that IP address .PARAMETER FwdDecIP This will take the decimal equivilent of the IP address and show all forms of the IP address .PARAMETER RevDecIP This will take the reverse decimal equivilent of the IP address and show all forms of the IP address .PARAMETER CIDRMask This will take a CIDR Mask integer and show it in all the address forms .NOTES General notes Created by: Brent Denny Created on: 25 Mar 2021 Modified on: 25 Mar 2021 #> [CmdletBinding(DefaultParameterSetName='Default')] Param ( [Parameter(ParameterSetName='ReverseIP')] [string]$RevIPAddress, [Parameter(ParameterSetName='ForwardIP')] [string]$FwdIPAddress, [Parameter(ParameterSetName='ForwardDecIP')] [string]$FwdDecIP, [Parameter(ParameterSetName='ReverseDecIP')] [string]$RevDecIP, [Parameter(ParameterSetName='CIDRMask')] [int]$CIDRMask ) if ($PSCmdlet.ParameterSetName -eq 'ReverseIP') { $IPOctetsArray = $RevIPAddress -split '\.' $FwdArray = 3..0 $RevArray = 0..3 } elseif ($PSCmdlet.ParameterSetName -eq 'ForwardIP') { $IPOctetsArray = $FwdIPAddress -split '\.' $FwdArray = 0..3 $RevArray = 3..0 } elseif ($PSCmdlet.ParameterSetName -eq 'ForwardDecIP') { $IPObj = [ipaddress]$FwdDecIP $IPOctetsArray = $IPObj.IPAddressToString -split '\.' $FwdArray = 0..3 $RevArray = 3..0 } elseif ($PSCmdlet.ParameterSetName -eq 'ReverseDecIP') { $IPObj = [ipaddress]$RevDecIP $IPOctetsArray = $IPObj.IPAddressToString -split '\.' $FwdArray = 3..0 $RevArray = 0..3 } elseif ($PSCmdlet.ParameterSetName -eq 'CIDRMask') { $BinaryMask = ('1' * $CIDRMask) + ('0' * (32 - $CIDRMask)) $DecimalMask = [convert]::ToInt64($BinaryMask,2) $IPObj = [ipaddress]$DecimalMask $IPOctetsArray = $IPObj.IPAddressToString -split '\.' $FwdArray = 3..0 $RevArray = 0..3 } $FwdIP = $IPOctetsArray[$FwdArray] -join '.' $FwdBinary = ($FwdArray | ForEach-Object { $Bin = [convert]::ToString($IPOctetsArray[$_],2) ('0' * (8 - $Bin.Length)) + $Bin }) -join '' $RevIP = $IPOctetsArray[$RevArray] -join '.' $RevBinary = ($RevArray | ForEach-Object { $Bin = [convert]::ToString($IPOctetsArray[$_],2) ('0' * (8 - $Bin.Length)) + $Bin }) -join '' $FnObjProp = [ordered]@{ ForwardIP = $FwdIP FwdDecIP = ([ipaddress]$RevIP).Address FwdBinary = $FwdBinary FwdBinaryGroups = $FwdBinary -replace '(\d{8})(\d{8})(\d{8})(\d{8})','$1 $2 $3 $4' ReverseIP = $RevIP RevDecIP = ([ipaddress]$FwdIP).Address RevBinary = $RevBinary RevBinaryGroups = $RevBinary -replace '(\d{8})(\d{8})(\d{8})(\d{8})','$1 $2 $3 $4' } New-Object -TypeName psobject -Property $FnObjProp } function Convert-CIDRMask { <# .SYNOPSIS Takes a CIDR subnet mask integer and displays it in many different formats .DESCRIPTION Using the CIDR mask provided, this will convert it to the following formats: CIDR Mask Binary Mask IPV4 Mask (forward and reverse) Decimal Mask (forward and reverse) Jump information (the count from subnet to subnet) .EXAMPLE Convert-CIDRMask -CIDRMask 20 This would produce this output, the reverse values are useful in PowerShell IP calulations CidrMask : 20 BinaryMask : 11111111111111111111000000000000 BinaryGroups : 11111111 11111111 11110000 00000000 IPv4FwdMask : 255.255.240.0 DecimalFwdMask : 4294963200 IPv4RevMask : 0.240.255.255 DecimalRevMask : 15794175 JumpIPs : 0.0.16.0 JumpDecIP : 4096 JumpRevIPs : 0.16.0.0 JumpDecRevIP : 1048576 JumpValue : 16 .PARAMETER CIDRMask Enter an integer for the CIDR subnet mask, for example if the mask is 255.255.240.0 the mask you would enter would be 20. .PARAMETER IPV4Mask Enter an IPV4 subnet mask, for example 255.255.240.0 .NOTES General notes Created by: Brent Denny Created on: 25 Mar 2021 Modified on: 25 Mar 2021 #> [cmdletbinding(DefaultParameterSetName='default')] Param ( [Parameter(ParameterSetName='CIDR')] [int]$CIDRMask, [Parameter(ParameterSetName='IP')] [string]$IPV4Mask ) if ($PSCmdlet.ParameterSetName -eq 'IP') { if ($IPV4Mask -notmatch '^(255\.(0|128|192|224|240|248|252|254|255)(\.0){2}|(255\.){2}(0|128|192|224|240|248|252|254|255)\.0|(255\.){3}(0|128|192|224|240|248|252|254|255))$') { Write-Warning 'Not a valid subnet mask' break } $Binary = (Show-IPFwdAndRev -FwdIPAddress $IPV4Mask).FwdBinary $CIDRMask = ($Binary -replace '^(1+)0+$','$1').length } else { if ($CIDRMask -notin @(8..30)) { Write-Warning 'Not a valid subnet mask' break } } $IPAddrInfo = Show-IPFwdAndRev -CIDRMask $CIDRMask $JumpRevDec = (Show-IPFwdAndRev -CIDRMask ($CIDRMask)).RevDecIP - (Show-IPFwdAndRev -CIDRMask ($CIDRMask-1)).RevDecIP $JumpInfo = Show-IPFwdAndRev -RevDecIP $JumpRevDec $JumpVal = [math]::Pow(2,(8-($CIDRMask % 8))) $FnObjProp = [ordered]@{ CidrMask = $CIDRMask BinaryMask = $IPAddrInfo.FwdBinary BinaryGroups = $IPAddrInfo.FwdBinary -replace '(\d{8})(\d{8})(\d{8})(\d{8})','$1 $2 $3 $4' IPv4FwdMask = $IPAddrInfo.ForwardIP DecimalFwdMask = $IPAddrInfo.FwdDecIP IPv4RevMask = $IPAddrInfo.ReverseIP DecimalRevMask = $IPAddrInfo.RevDecIP JumpIPs = $JumpInfo.ForwardIP JumpDecIP = $JumpInfo.FwdDecIP JumpRevIPs = $JumpInfo.ReverseIP JumpDecRevIP = $JumpInfo.RevDecIP JumpValue = $JumpVal } New-Object -TypeName psobject -Property $FnObjProp } function New-SubnetPSSessions { <# .SYNOPSIS Creates PS Sessions with every host in subnet .DESCRIPTION Creates PS sessions with all machines that are in the subnet .EXAMPLE New-SubnetPSSessions After the command runs use $Sessions = Get-PSSession to collect the sessions into a single variable .NOTES General notes Created by: Brent Denny Created on: 25 Mar 2021 Modified on: 25 Mar 2021 #> Set-Item -Path WSMan:\localhost\Client\TrustedHosts -Value * -Force $MyIp = ((ipconfig /all).trim() | Select-String -Pattern '^IPV4 Address' ) -replace '(^.+\:\s|\(Preferred\))','' | Sort-Object @{e={($_ -replace '.*\.','') -as [int] }} $MySubnetMask = ((ipconfig /all).trim() | Select-String -Pattern '^Subnet Mask' ) -replace '^.+\:\s','' $IPRawText = (ipconfig /all).trim() | Select-String -Pattern '^(DHCP Server|Default Gateway|DNS Servers|IPV4 Address)' $IPArrayToExclude = $IPRawText -replace '(^.+\:\s|\(Preferred\))','' | Sort-Object @{e={($_ -replace '.*\.','') -as [int] }} $Mask = (Convert-CIDRMask -IPV4Mask $MySubnetMask).CIDRMask $MaskFormats = Convert-CIDRMask -CIDRMask $Mask $JumpSize = $MaskFormats.JumpValue $ValidIPJump = $JumpSize - 2 $IP = [ipaddress]$MyIp $DecSubnetID = $IP.Address -band $MaskFormats.DecimalRevMask $SubnetIDIP = Show-IPFwdAndRev -FwdIPAddress ([ipaddress]$DecSubnetID).IPAddressToString $FirstDecIP = [ipaddress](1 + $SubnetIDIP.FwdDecIP) $FirstIP = Show-IPFwdAndRev -RevIPAddress $FirstDecIP.IPAddressToString $ClassRoomIPs = foreach ($LastOctet in (1..$ValidIPJump)) { $NewIP = $FirstIP.ForwardIP -replace '\.\d{1,3}$',".$LastOctet" if ($NewIP -notin $IPArrayToExclude) { $NewIP } } New-PSSession -ComputerName $ClassRoomIPs *> $null } |