How to find open TCP Ports in Windows - 17-Feb-2025
Every Windows server and client provides TCP ports through which a
TCP connection can be established. Even if a server still responds
to a ping, it is possible that a connection is no longer possible on
those TCP ports. Checking the TCP ports periodically is a good way
to determine if a server is working properly. In most cases, TCP
ports are made available by Windows “Services”.
Here we refer to the device that makes TCP ports available as a
"server". This can also be a Windows client, a router or switch or any
other device that communicates via TCP/IP in the network.
The client provides a TCP port on port 3389 (RDP).
► Option 2: netstat command on the Windows
server
You can see the connections on the server in the same way - if you
have administrative access to the server. Simply enter
netstat -a in a command prompt.
PortCheck.exe MyServer 1-50000
or
PortCheck.exe MyServer knownports
to check entire ranges. TCP ports that are displayed here in green
are responding.
More examples:
PortCheck Fileserver1,Fileserver2 445
# multiple servers, single port
Important TCP ports:
21 (FTP - File Transfer Protocol), 22 (SSH - Secure Shell), 23 (Telnet), 25 (SMTP
- Simple Mail Transfer Protocol), 80 (HTTP - Hypertext Transfer
Protocol), 110 (POP3),
135 (DCE / WMI), 139 (NetBIOS), 143 (IMAP4), 443 (HTTPS), 445 (SMB -
Server Message Block),
1433 (MS SQL), 1494 (ICA - Citrix), 1521 (Oracle), 3389 (RDP)
>>> Change to the
TCP
Port check PowerShell page