New Question
 
 
PRTG Network Monitor

Intuitive to Use.
Easy to manage.

300.000 administrators have chosen PRTG to monitor their network. Find out how you can reduce cost, increase QoS and ease planning, as well.

Free PRTG
Download >>

 

What is this?

This knowledgebase contains questions and answers about PRTG Network Monitor and network monitoring in general. You are invited to get involved by asking and answering questions!

Learn more

 

Top Tags


View all Tags


I want to know the principle of 'port' sensor, how it works

Votes:

0

Your Vote:

Up

Down

Let me know how 'port' sensor works. What is a way to check port state? 'netstat' or 'telnet' command?

On what basis will port be checked whether 'open' or 'closed' in TCP session?

For example, When I used the command 'netstat' in cmd for checking 1433 port state as below, PRTG 'port' sensor can check the keyword 'ESTABLISHED' or 'LISTENING' ?

-------------------------------------------------------------------------------------------------

C:\Users\Administrator>netstat -ano|findstr 1433
  TCP    0.0.0.0:1433           0.0.0.0:0              LISTENING       2324
  TCP    127.0.0.1:49212        127.0.0.1:1433         TIME_WAIT       0
  TCP    127.0.0.1:49236        127.0.0.1:1433         TIME_WAIT       0
  TCP    127.0.0.1:49263        127.0.0.1:1433         TIME_WAIT       0
  TCP    127.0.0.1:49288        127.0.0.1:1433         TIME_WAIT       0
  TCP    192.168.0.42:1433      192.168.0.188:58546    ESTABLISHED     2324
  TCP    192.168.0.42:1433      192.168.0.200:59802    ESTABLISHED     2324
  TCP    192.168.0.42:49213     192.168.0.153:1433     TIME_WAIT       0
  TCP    192.168.0.42:49219     192.168.0.153:1433     TIME_WAIT       0
  TCP    192.168.0.42:49237     192.168.0.153:1433     TIME_WAIT       0
  TCP    192.168.0.42:49245     192.168.0.153:1433     TIME_WAIT       0
  TCP    192.168.0.42:49267     192.168.0.153:1433     TIME_WAIT       0
  TCP    192.168.0.42:49271     192.168.0.153:1433     TIME_WAIT       0
  TCP    192.168.0.42:49289     192.168.0.153:1433     TIME_WAIT       0
  TCP    192.168.0.42:49297     192.168.0.153:1433     TIME_WAIT       0
  TCP    [::]:1433              [::]:0                 LISTENING       2324
-------------------------------------------------------------------------------------------------

netstat port sensor telnet

Created on Oct 25, 2019 3:56:33 AM by  Jonathan_Jung (0) 1

Last change on Oct 25, 2019 4:22:59 AM by  Sven Roggenhofer [Paessler Technical Support]



3 Replies

Votes:

1

Your Vote:

Up

Down

Hi,

The Port sensor only uses telnet and the sensor can check if the port is open or closed.
You'll find more information about the Port sensor here.

Kind regards.

Created on Oct 25, 2019 8:14:57 AM by  Marijan Horsky [Paessler Support]



Votes:

0

Your Vote:

Up

Down

Hi,

Does PRTG run the telnet command directly on the cmd?

(example) > telnet 8.8.8.8 3389

Created on Jan 2, 2020 12:47:46 AM by  Jonathan_Jung (0) 1



Votes:

0

Your Vote:

Up

Down

Hi Jonathan,

The sensor uses the service and doesn't run it directly in the cmd.

Kind regards.

Created on Jan 2, 2020 8:23:33 AM by  Marijan Horsky [Paessler Support]



Please log in or register to enter your reply.


Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.