Month: October 2010

Quickly Find Local Open Ports

sysop

Usually, if you want to see all the used and listening ports on your computer, you’d use the NETSTAT command.

Note: The NETSTAT command will show you whatever ports are open or in use, but it is NOT a port scanning tool! If you want to have your computer scanned for open ports see this page instead (link will follow shortly).

Open Command Prompt and type:

C:'WINDOWS>netstat -an |find /i "listening"
TCP   0.0.0.0:135   0.0.0.0:0   LISTENING
TCP   0.0.0.0:445   0.0.0.0:0   LISTENING
TCP   0.0.0.0:1025   0.0.0.0:0   LISTENING
TCP   0.0.0.0:1084   0.0.0.0:0   LISTENING
TCP   0.0.0.0:2094   0.0.0.0:0   LISTENING
TCP   0.0.0.0:3389   0.0.0.0:0   LISTENING
TCP   0.0.0.0:5000   0.0.0.0:0   LISTENING

You can redirect it to a text file by adding >c:’openports.txt to the command, if you want to:

    netstat -an |find /i "listening" > c:'openports.txt

netstat -an |find /i “listening” > c:’openports.txt

You can also change “listening” to “established” to see what ports your computer actually communicates with:

    C:'WINDOWS>netstat -an |find /i "established"
    TCP   192.168.0.100:1084   192.168.0.200:1026   ESTABLISHED
    TCP   192.168.0.100:2094   192.168.0.200:1166   ESTABLISHED
    TCP   192.168.0.100:2305   209.211.250.3:80   ESTABLISHED
    TCP   192.168.0.100:2316   212.179.112.230:80   ESTABLISHED
    TCP   192.168.0.100:2340   209.211.250.3:110   ESTABLISHED

Note: In Windows XP and Windows Server 2003, you can type NETSTAT -O to get a list of all the owning process ID associated with each connection:

C:'WINDOWS>netstat -ao |find /i "listening"
TCP   pro1:epmap   pro1.dpetri.net:0   LISTENING   860
TCP   pro1:microsoft-ds   pro1.dpetri.net:0   LISTENING   4
TCP   pro1:1025   pro1.dpetri.net:0   LISTENING   908
TCP   pro1:1084   pro1.dpetri.net:0   LISTENING   596
TCP   pro1:2094   pro1.dpetri.net:0   LISTENING   596
TCP   pro1:3389   pro1.dpetri.net:0   LISTENING   908
TCP   pro1:5000   pro1.dpetri.net:0   LISTENING   1068

You can use PULIST from the W2K Resource Kit (Download Free Windows 2000 Resource Kit Tools) to find the PID and see what process uses it and who started it. For example, you found out that your computer had an open connection to a remote IP address on TCP port 80, and you don’t have any Internet Explorer or other browser windows open. You want to find out what process is using that session.

C:'WINDOWS>netstat -no

Active Connections

Proto Local Address Foreign Address State PID
TCP   192.168.0.100:2496   212.179.4.7:80   ESTABLISHED   1536

You can then use PULIST with the FIND command:

C:'WINDOWS>pulist |find /i "1536"

Process   PID   User
LUCOMS~1.EXE   1536   DPETRI'danielp

In this case, LUCOMS~1.EXE is run by DANIELP (myself) and as it happens, it’s the Symantec Live Update process.

You can also look in Task Manager for the respective PID.

  1. To set up Task Manager to show the PID column open Task Manager by using CTRL+SHIFT+ESC.
  2. Go to the Processes tab, click View and then Select Columns.

  1. In the Select Columns windows click to select PID and then click Ok.

  1. You can sort the PID column to display the PIDs in descending or ascending order.