Update @ 3:58 pm: At risk of losing the one-liner nomenclature at a very worthwhile increase in speed, read below.
The One-Liner WMI Version
One-liner to retrieve the first IP address of the first adapter which has a default gateway set. This is a very reliable, yet not perfect technique for determining the "right" IP address. It will work well in all but the most complex of network configuration scenarios.
@( Get-WmiObject Win32_NetworkAdapterConfiguration | Where-Object { $_.DefaultIpGateway } )[0].IPAddress[0]
Note that I have used the @() array notation around the Get-WmiObject call so that I don’t have to worry about how many network adapters come back. If only one comes back, I have an array with one item. If I didn’t do this, then I would have to do an if statement to check whether it’s an array (meaning that the system has multiple NICs with default gateways—which is super-rare but possible).
The .NET Class Method
It’s no longer a single line, but honestly, length is not a measure of quality in scripting. I noticed that the above WMI call was noticeably sluggish. Measurements with Measure-Command cmdlet showed an average execution time of 455 milliseconds. Here’s a different way using the Net.NetworkInformation.NetworkInterface .NET class.
$allNIC = [system.Net.NetworkInformation.NetworkInterface]::GetAllNetworkInterfaces()
$PrimaryNIC = $allNIC | Where-Object { $_.GetIPProperties().GatewayAddresses }
$PrimaryNIC.GetIPProperties().UnicastAddresses[0].Address.IPAddressToString
New time averages 13 milliseconds on my system. That’s a huge difference which I was not surprised to see based on past experience.
You could keep it as a oneliner
PS>[system.Net.NetworkInformation.NetworkInterface]::GetAllNetworkInterfaces() |
Where-Object {$_.GetIPProperties().GatewayAddresses} |
ForEach-Object {$_.GetIPProperties().UnicastAddresses|
Foreach-object{$_.Address.IPAddressToString}
}
I added the second foreach loop b/c my systems have both an IPv4 & IPv6 address
~Glenn
I ran into an issue with the .NET part. The first example runs fine for me, but on 2 different systems I have I got the following when running the second method:
Method invocation failed because [System.Object[]] doesn’t contain a method named ‘GetIPProperties’.
At :line:3 char:27
+ $PrimaryNIC.GetIPProperties <<<< ().UnicastAddresses[0].Address.IPAddressToString
if I replace your last line with:
foreach ($nic in $PrimaryNIC){
$nic.GetIPProperties()
}
I get:
Object reference not set to an instance of an object.
At :line:0 char:0
I have attempted some debugging of my own but have run to the end of my knowledge of PowerShell.
Brad, Glenn’s version doesn’t work? I suspect that you’ve got IPV6 enabled, right?
No IPV6 configured and no output from Glenn’s script.