EnvSetup.ps1

param(
    [Parameter(Mandatory = $false,HelpMessage="What you want to rename comp to")][String] $hostName,
    [Parameter(Mandatory = $false,HelpMessage="What you want ip to be")][String] $ip,
    [Parameter(Mandatory = $false,HelpMessage="Repoint to 192.168.1.166")][Switch] $DNS,
#    [Parameter(Mandatory = $true)][String] $ipMode,
    [Parameter(Mandatory = $false,HelpMessage="Name of rule, e.g. Allow My Rules")][String] $firewallRuleName,
    [Parameter(Mandatory = $false,HelpMessage="The port numbers: 25,587,32400,8080,8085")] $firewallRulePort
)

$Logfile = "C:\Logs\$($MyInvocation.MyCommand.Name).log"
function LogWrite($logString)
{
   Add-content $Logfile -value $logString 
}

function changeIP ($ip) {
    try {
        $currName = hostname
        $ipOld = Test-Connection -ComputerName $currName -Count 1 | Select-Object IPV4Address

        if ($ipOld -ne $ip) {
            #Write-Host "IP changed"
            Remove-NetIPAddress -IPAddress $ipOld -InterfaceAlias Ethernet0 -AddressFamily IPv4 -PrefixLength 24 -DefaultGateway 192.168.1.1
            New-NetIPAddress -IPAddress $ip -InterfaceAlias 'Ethernet0' -PrefixLength 24 -DefaultGateway 192.168.1.1
        }else {
            Write-Host "Current IP is: $($ipOld) and new IP is : $($ip). Nothing changed"
        }
    }
    catch{
        LogWrite($_.Exception.Message)
    }
}

function changeDNS (){
    try{
        #Write-Host "DNS changed"
        Set-DnsClientServerAddress -ServerAddresses ("192.168.1.166", "8.8.8.8") -InterfaceAlias Ethernet0
    }
    catch{
        LogWrite($_.Exception.Message)
    }
}

function firewallRules($name, $port){
    try{
        #Write-Host "firewall rule changed"
        New-NetFirewallRule -DisplayName $name -Direction Inbound -LocalPort $port -Protocol TCP -Action Allow -Group 
    }
    catch{
        LogWrite($_.Exception.Message)
    }
}

function renameComputer ($newName){
    try{
        #Write-Host "computer name changed"
        Rename-Computer -NewName $hostName 
    }
    catch{
        LogWrite($_.Exception.Message)
    }
}

changeIP -ip $ip
changeDNS
firewallRules -name $firewallRuleName -port $firewallRulePort
renameComputer -newName $hostName