How to Discover Active Ports on a Windows Machine

PS C:\Users\kimconnect> get-nettcpsetting | select SettingName,DynamicPortRangeStartPort,DynamicPortRangeNumberOfPorts

SettingName DynamicPortRangeStartPort DynamicPortRangeNumberOfPorts
----------- ------------------------- -----------------------------
Automatic
InternetCustom 49152 16384
DatacenterCustom 49152 16384
Compat 49152 16384
Datacenter 49152 16384
Internet 49152 16384

Step 1: discover inbound ports that are actively used

netstat | findstr -i "ESTABLISHED LISTEN CLOSE_WAIT TIME_WAIT"

Step 2: find all outbound dynamic ports that are expected to be allowed through the firewalls

netsh int ipv4 show dynamicport tcp

Please note that the output of this command does not explicitly provide the named end-port. Thus, we must add the “starting port” number with the “number of ports” to derive at that value. In the example below, 49152 + 16384 = 65536

Leave a Reply

Your email address will not be published. Required fields are marked *