Introduction: I have created a bash function that is able to check whether a port is available and increments it by 1 if false until a certain maximum port number. E.g., if port 500 is unavailable then the availability of 501 will be checked until 550.
Aim: In order to test this bash function I need to create a range of ports that are in LISTEN state.
Attempts: On Windows it is possible to create a LISTEN port using these PowerShell commands:
PS C:\Users\u> netstat -nat | grep 1234 PS C:\Users\u> $listener = [System.Net.Sockets.TcpListener]1234 PS C:\Users\u> $listener.Start(); PS C:\Users\u> netstat -nat | grep 1234 TCP 0.0.0.0:1234 0.0.0.0:0 LISTENING InHost PS C:\Users\u> $listener.Stop(); PS C:\Users\u> netstat -nat | grep 1234 PS C:\Users\u>
Based on this I was trying to think about a command that could do the same on CentOS, but I do not know why and I started to Google without finding a solution that solves this issue.
Expected answer: I will accept and upvote the answer that contains a command that is able to create a LISTEN port and once the command has been run the port should stay in LISTEN state, i.e.:
[user@host ~]$ ss -nat | grep 500 LISTEN 0 128 *:500 *:*