nc netcat opening listening ports – Netcat scan examples
Establish a connection to a remote port if open:

[~]# nc -vn 192.168.2.101 22
Ncat: Connected to 192.168.2.101:22.
SSH-2.0-OpenSSH\_7.6

As you see, netcat was able to reach 22 port and establish the connection successfully.

UDP port connections are also allowed with netcat, as you can see in the next example:

[~]# ncat -v -u 1.1.1.1 53
Ncat: Version 7.60 ( https://nmap.org/ncat )
Ncat: Connected to 1.1.1.1:53.

Netcat also has the ability to open a remote backdoor on the target system for 5000ms, see below: