Open the command prompt - start » run » cmd or start » All Programs » Accessories » Command Prompt.
Checking SQL connections.
telnet [Server Name] 1433
If encountered below message,
'telnet' is not recognized as an internal or external command,
operable program or batch file.
Open Control Panel and add Telnet Client.
Checking active port connections.
List Active Connection
netstat -an
List Active Connection with Application Process ID
netstat -abo
Checking which application is using a port.
Type netstat -aon | findstr '[port_number]'. Replace the [port_number] with the actual port number that you want to check and hit enter. For example,
netstat -abo | find "30010"
If the port is being used by any application, then that application’s detail will be shown. The number, which is shown at the last column of the list, is the PID (process ID) of that application. Make note of this.
Type tasklist | findstr '[PID]'. Replace the [PID] with the number from the above step and hit enter.
Checking which port is being used by a application
Open the command prompt - start » run » cmd or start » All Programs » Accessories » Command Prompt.
Type tasklist | findstr '[application_name]'. Replace the [application_name] with the application that you want to check (for example, apache) and hit enter.
Make note of the PID (second column) from the details shown.
Type netstat -aon | findstr '[PID]'. Replace the [PID] from the above step and hit enter.
You’ll be shown the application detail and the corresponding port to which it is listening.
HELP
Displays protocol statistics and current TCP/IP network connections.
netstat /?
NETSTAT [-a] [-b] [-e] [-f] [-n] [-o] [-p proto] [-r] [-s] [-x] [-t] [interval]
-a Displays all connections and listening ports.
-b Displays the executable involved in creating each connection or listening port. In some cases well-known executables host multiple independent components, and in these cases the sequence of components involved in creating the connection or listening port is displayed. In this case the executable name is in [] at the bottom, on top is the component it called, and so forth until TCP/IP was reached. Note that this option can be time-consuming and will fail unless you have sufficient permissions.
-e Displays Ethernet statistics. This may be combined with the -s option.
-f Displays Fully Qualified Domain Names (FQDN) for foreign addresses.
-n Displays addresses and port numbers in numerical form.
-o Displays the owning process ID associated with each connection.
-p proto Shows connections for the protocol specified by proto; proto may be any of: TCP, UDP, TCPv6, or UDPv6. If used with the -s option to display per-protocol statistics, proto may be any of: IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, or UDPv6.
-q Displays all connections, listening ports, and bound nonlistening TCP ports. Bound nonlistening ports may or may not
be associated with an active connection.
-r Displays the routing table.
-s Displays per-protocol statistics. By default, statistics are shown for IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, and UDPv6;
the -p option may be used to specify a subset of the default.
-t Displays the current connection offload state.
-x Displays NetworkDirect connections, listeners, and shared endpoints.
-y Displays the TCP connection template for all connections. Cannot be combined with the other options. interval Redisplays selected statistics, pausing interval seconds between each display. Press CTRL+C to stop redisplaying
statistics. If omitted, netstat will print the current configuration information once.