Better than Just Pinging

Last updated Oct 21, 2023

• Troubleshooting
• Powershell
• Bash
• Terminal tip tuesdays

I’m sure we have all pinged something during troubleshooting at one point or another. But what if, in the same amount of steps as pinging, we could test more than just if the IP address was reachable?

PowerShell has a great command built in Test-NetConnection. This command lets you both ping the target host, but also test if you can connect on a specific port. This is extremely helpful when troubleshooting web services or interfaces that listen on specific ports.

Let’s say you have some kind of interface server and you’re trying to verify if it is listening properly. You could just ping the server, but all that tells you is that the remote host is connected to the network. It doesn’t mean anything as far as that interface service goes. Say your server is “server” and it has an interface that listens on port 443. Instead of just pinging, you can do this:

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Test-NetConnection server -Port 443

This will ping the server and also attempt a TCP connect on Port 443. The successful results look something like this:

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ComputerName     : server
RemoteAddress    : 192.168.0.1
RemotePort       : 443
InterfaceAlias   : Ethernet
SourceAddress    : 192.168.0.2
PingSucceeded    : True
TcpTestSucceeded : True

If the ping is successful but the test fails to connect on the specified port, the output looks something like this:

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ComputerName     : server
RemoteAddress    : 192.168.0.1
RemotePort       : 443
InterfaceAlias   : Ethernet
SourceAddress    : 192.168.0.2
PingSucceeded    : True
TcpTestSucceeded : False

If the host isn’t even pingable, the output looks like this instead:

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ComputerName           : server
RemoteAddress          : 192.168.0.1
RemotePort             : 443
InterfaceAlias         : Ethernet 3
SourceAddress          : 192.168.0.2
PingSucceeded          : False
PingReplyDetails (RTT) : 0 ms
TcpTestSucceeded       : False

Now we know that not only is the remote server up, but we’re able to connect on the port that the interface uses. That puts us one step closer to a solution, and takes no more steps than simply pinging!

Note: If you want to shorten up this command, you can use it’s alias! You can replace Test-NetConnection with simply tnc.

Many Linux distributions either have netcat built-in, or available for installation. This tool offers at least the same functionality as the above PowerShell method. To perform the same test:

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netcat -vz server 443

This will attempt a ping and then TCP connect on Port 443 of the remote server. The output will look something like this if successful:

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Connection to 192.168.0.1 443 port [tcp/http] succeeded!

If the host is pingable but the test failed to connect on the specified port, it will look like this:

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nc: connect to 192.168.200.1 port 443 (tcp) failed: Connection refused

If the host isn’t even pingable, then the command hangs and does not return output.

Note: If you want to shorten up this command, you can use it’s alias! You can replace netcat with simply nc.

The above methods aid us in gathering more information in a single step during troubleshooting, thus saving a little bit of time and moving us closer to a resolution. The next time you are about to ping something, do consider using the above methods instead!

• Test-NetConnection Documentation
• About netcat