Introduction

Netstat (Netstat.exe) is a command-line tool that displays TCP/IP protocol statistics and active connections to and from your computer. Netstat also provides an option to display the number of bytes sent and received, as well as network packets dropped (if any). You can use this tool to quickly verify the number of connections opened on a certain port.

Test for open connections on Port 5252 (Default port used by K2.net™ 2003 Server)

Open a Windows Command Prompt, type in the following command (case insensitive) and press ‘Enter’.

NETSTAT -N -P TCP | FIND /C "5252"

The number of open TCP/IP connections to port 5252 will be returned in the next line.

Syntax
netstat [-a] [-e] [-n] [-o] [-p Protocol] [-r] [-s] [Interval]

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, the 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.

Interval
Redisplays the selected information every Interval seconds. Press CTRL+C to stop the redisplay. If this parameter is omitted, netstat prints the selected information only once.

Find
The find command searches for a text string in a file or files. If a file or path is not specified, find searches the text typed at the prompt or piped from another command.
The [/C] command switch displays only the count of lines containing the specified string.

/?
Displays help at the command prompt.

Remarks
Parameters used with this command must be prefixed with a hyphen (-) rather than a slash (/).
Netstat provides statistics for the following:

Proto
The name of the protocol (TCP or UDP).

Local Address
The IP address of the local computer and the port number being used. The name of the local computer that corresponds to the IP address and the name of the port is shown unless the -n parameter is specified. If the port is not yet established, the port number is shown as an asterisk (*).

Foreign Address
The IP address and port number of the remote computer to which the socket is connected. The names that corresponds to the IP address and the port are shown unless the -n parameter is specified. If the port is not yet established, the port number is shown as an asterisk (*).

(state)
Indicates the state of a TCP connection. The possible states are as follows:

CLOSE_WAIT
CLOSED
ESTABLISHED
FIN_WAIT_1
FIN_WAIT_2
LAST_ACK
LISTEN
SYN_RECEIVED
SYN_SEND
TIMED_WAIT

For more information about the netstat, see http://technet.microsoft.com/en-us/library/bb490947.aspx

This command is available only if the Internet Protocol (TCP/IP) protocol is installed as a component in the properties of a network adapter in Network Connections.