Microsoft PowerShell can be uses to a lot of amazing stuff. I have been using PowerShell for years now, but I am still learning new cool stuff it can do.
PowerShell contains a lot of cmdlets making it easy to complete all kinds of tasks. This also includes network tasks. Furthermore I will demonstrate some of these for cmdlets for you in this post .
Ping, just smarter
One of the must used command for any IT workers across the world, is the ping command. It is used to check if a computer(host) is “alive”. PowerShell has a command for that as well. In PowerShell the command is named Test-Connection. It can do the same as a normal ping command, but have other options as well:
Source Destination IPV4Address IPV6Address Bytes Time(ms)
WINDOWS10 google.com 172.217.17.142 32 19
WINDOWS10 google.com 172.217.17.142 32 23
WINDOWS10 google.com 172.217.17.142 32 19
WINDOWS10 google.com 172.217.17.142 32 19
You can also ping multiple host in one command like this:
Source Destination IPV4Address IPV6Address Bytes Time(ms)WINDOWS10 google.com 172.217.17.46 32 23
WINDOWS10 google.com 172.217.17.46 32 19
WINDOWS10 localhost 127.0.0.1 ::1 32 0
WINDOWS10 localhost 127.0.0.1 ::1 32 0
WINDOWS10 WINDOWS10 192.168.1.78 fe80::dd74:b80f:5c2c:21cc%12 32 0
WINDOWS10 WINDOWS10 192.168.1.78 fe80::dd74:b80f:5c2c:21cc%12 32 0
Test if a firewall port is open at a remote host using PowerShell
Another useful PowerShell cmdlets is the Test-NetConnetion. This command can be useful testing if a specific port is open at a remote hosts firewall.
Let us try and see if port 3389 (RDP) is open on my RDS server named WIN2012-RDS01:
ComputerName : WIN2012-RDS01
RemoteAddress : fe80::2c5f:6662:d4a9:8286%12
RemotePort : 3389
InterfaceAlias : vEthernet (vSwitch1) 2
SourceAddress : fe80::dd74:b80f:5c2c:21cc%12
TcpTestSucceeded : True
As you can see the command returns “TcpTestSucceeded: True” which means that the port is open. If it was not the case it would have returned “False”
Now let us test of telnet port 21 is also open:
WARNING: TCP connect to (fe80::2c5f:6662:d4a9:8286%12 : 21) failed
WARNING: TCP connect to (192.168.1.100 : 21) failedComputerName : WIN2012-RDS01
RemoteAddress : fe80::2c5f:6662:d4a9:8286%12
RemotePort : 21
InterfaceAlias : vEthernet (vSwitch1) 2
SourceAddress : fe80::dd74:b80f:5c2c:21cc%12
PingSucceeded : True
PingReplyDetails (RTT) : 0 ms
TcpTestSucceeded : False
As you can see in this case the TcpTestSucceeded returns “False” means that there is nothing answering on port 21 on my server. It might be the servers firewall that is blocking this port or just the fact that no software is listening on port 21.
PowerShell script using Test-Netconnection
With the above in mind, let’s try to write a small PowerShell script that checks a number of computers on a list for respond on a given port. In this example it is port 3389, but you can change it to whatever you like:
$ComputerList = @(“localhost”, “Windows10”, “Server”)
$port = 80
foreach ($computer in $ComputerList)
{
Write-Host “Checking RDP on $Computer…” -ForegroundColor Cyan
$Testresult = Test-NetConnection -Computername $Computer -Port $port -InformationLevel Detailed
}
Test this script above, by coping the code to the PowerShell ISE and just change the name of the computers you want to test. It does not need to be computers. It can be any device with an IP address, like a printer or a router.
Questions or Comments below
I hope you found the above as interesting as I do and that you got inspired to use PowerShell the next time you want to perform simple network tasks. If you want to dig deeper, there is many more great PowerShell commands working with network. Furthermore, if you have questions or comments, please use the comment formular below.
This is only for TCP ports, How to test a UDP port? E.G NetTime uses UDP port 123
It is difficult to test UDP ports because there is no response in UDP communication.