DDNS without DDNS: The PowerShell Edition

I've been meaning to do this for a while. My Wife needs tech support at home while I am at work every once in a while, but it is often something that I need to see to help her with. However, I don't afford the convenience of a static IP address from my ISP, so I am usually unable to connect to her computer remotely. Hence, the need to know what my public address is.

Now I know that anyone lured into this blog post by the title will be asking, "Colin, why not use a DDNS provider?", and the answer would be, "Because I don't want to!". It's a lot easier to justify spent time on technology to your wife than it is to justify spent money. ;)

So, the code:


#Send-IP2Gmail.ps1
#$F = File
#$U = Username
#$P = Password
#$B = Browser
#$C = Credentials
#$E = Email Address
#$I = IP Address
#$S = SMTP Server

function Store-myPass
{
$global:U = $args[0]
$global:F = $args[1]
$Credential = Get-Credential $U
$credential.Password | ConvertFrom-SecureString | Set-Content $F
}

function Get-myCred
{
$U = $args[0]
$F = $args[1]
$P = Get-Content $F | ConvertTo-SecureString
$C = New-Object System.Management.Automation.PsCredential($U,$P)
$C
}

function Send-IP
{
$U = $args[0]
$F = $args[1]
$C = get-myCred $U $F
$url = "http://www.whatismyip.com/automation/n09230945.asp"
$browser = New-Object Net.Webclient
$S = "smtp.gmail.com"
$E = $U + "@gmail.com"
$I = $browser.DownloadString($url)
Send-MailMessage -to $E -from $E -Subject $I -Credential $C -SmtpServer $S -UseSsl
}

$Uv1 = $args[0]
$Setup = $args[1]

if ($args[0] -eq $null){
Write-Host ""
Write-Host ""
Write-Host -ForegroundColor Yellow "Welcome to Send-IP2Gmail Usage Instructions!"
Write-Host ""
Write-Host ""
Write-Host -ForegroundColor Yellow "Running this cmdlet without specifying a username will bring you to this message."
Write-Host -ForegroundColor Yellow 'For initial configuration, or to change your password, use the "setup" command:'
Write-Host ""
Write-Host -ForegroundColor Red ".\Send-IP2Gmail davidcolinsmith setup"
Write-Host ""
Write-Host ""
Write-Host -ForegroundColor Yellow "After this command is run, your password is securely hashed in a file in the "
Write-Host -ForegroundColor Yellow 'C:\creds\ folder. Subsequent use of this command without the "setup"'
Write-Host -ForegroundColor Yellow "feature can be schedule or scripted using this syntax:"
Write-Host ""
Write-Host -ForegroundColor Red ".\Send-IP2Gmail davidcolinsmith"
Write-Host ""
}
else{

if ($Setup -eq "setup")
{
$U = $Uv1
$Result = test-path -path "c:\creds"
if (!(test-path -path "c:\creds"))
{
new-item c:\creds -type directory
$credspath = "c:\creds\" + $U + ".txt"
if (!(test-path -path $credspath))
{
new-item $credspath -type file
}
else{}
Write-Host "Send your Public DHCP-assigned IP address to your gMail account"
[environment]::SetEnvironmentVariable("Send-IP-Username", $U, "User")
$global:F = "c:\creds\" + $U + ".txt"
[environment]::SetEnvironmentVariable("Send-IP-CredPath", $F, "User")
Store-myPass $U $F
}
else{
Write-Host "Send your Public DHCP-assigned IP address to your gMail account"
[environment]::SetEnvironmentVariable("Send-IP-Username", $U, "User")
$global:F = "c:\creds\" + $U + ".txt"
[environment]::SetEnvironmentVariable("Send-IP-CredPath", $F, "User")
Store-myPass $U $F
}
}
else {
$U = get-childitem env:send-ip-username
$F = get-childitem env:Send-IP-CredPath
$U = $U.value
$F = $F.value
}
Send-IP $U $F
}


Comments, questions, concerns, or suggestions are welcome!