As the following list illustrates, Netstat has several parameters (using netstat /? in a command prompt window will display all available command-line parameters):
-a -- Displays all active TCP connections and the TCP and UDP ports on which the computer is listening.
-e -- Displays Ethernet statistics, such as the number of bytes and packets sent and received. This parameter can be combined with -s.
-n -- Displays active TCP connections; however, addresses and port numbers are expressed numerically and no attempt is made to determine names.
-o -- Displays active TCP connections and includes the process ID (PID) for each connection. You can find the application based on the PID on the Processes tab in Windows Task Manager. This parameter can be combined with -a, -n and -p.
-p Protocol -- Shows connections for the protocol specified by protocol. In this case, protocol can be tcp, udp, tcpv6, or udpv6. If this parameter is used with -s to display statistics by protocol, protocol can be tcp, udp, icmp, ip, tcpv6, udpv6, icmpv6, or ipv6.
-s -- Displays statistics by protocol. By default, statistics are shown for the TCP, UDP, ICMP, and IP protocols. If the IPv6 protocol is installed, statistics are shown for the TCP over IPv6, UDP over IPv6, ICMPv6 and IPv6 protocols. The -p parameter can be used to specify a set of protocols.
-r -- Displays the contents of the IP routing table. This is equivalent to the route print command.
Combining Netstat commands with Task Manager in Windows XP will allow you to determine active TCP/IP ports.