Monitoring TCP Ports
- 09-Apr-2025
Every server, client and router provides TCP
ports that enable other network devices to establish a communication
connection. This is a typical feature of client-server computing.
The TCP ports are logical ports, which are distinguished by the
port number. The number is in the range from 0 to 65535 - the
"well-known" ports (0 - 1023), the "registered" ports (1024 - 49151)
and the "dynamic and private" ports (49152 - 65535).
By regularly checking a specific TCP port, it is
possible to determine whether a server is still functioning
correctly. A TCP port check is a more detailed test than a ping
because it checks whether certain services are available on the
server. If the ping works, it only means that the server still has a
network connection. If the TCP port check works,
however, the server is still providing services on this port. The word “server” is used here in the sense of “network
device that provides TCP ports”. It can also be a client or
another network device.
There are many different tools on the market for
monitoring TCP ports, for example WhatsUp Gold, OpManager or PRTG.
These tools are suitable for continuous monitoring over months. The
usual monitoring intervals are 2 - 5 minutes. Various alarm
procedures are available, for example sending an e-mail in the event
of a failure. The tools are server-based and implementation usually
takes place within a project. These tools are less suitable for second-by-second
monitoring.
To find open TCP ports, open a command prompt on the server and have a look at the netstat -a
command. The command shows you all existing connections and all
connections on which the server is listening. You can also run
netstat -a on the client to see which servers the
client has established a connection with. You can find more details
about open TCP ports
in the article
Find open TCP ports in Windows.
Additional articles:
Content:
How to monitor
TCP ports, Free ping
monitoring tool, Open source ping
monitoring tool