North Carolina (USA)

remote login

Methods/steps

1. First, ports are divided into tcp and udp, so the same port number is also divided into tcp and udp protocols.

2. telnet is the most commonly used tool, but telnet uses tcp protocol, in other words, telnet can only detect whether this port of tcp is open.

Suppose it depends on whether the tcp 22 port of IP192.193.211is open, then run telnet192.192.

4. If the following message appears, the table display port is not open.

5. In addition to telnet, there is also a command nc to check whether the port is open.

6. Also check whether tcp 22 port is open to run nc. -z192.192.193.21122, the following information will appear when you open it:

7. If you want to check whether udp 22 port is open and running? NC–Uz192.192.193.438+0122, open it and the following information will appear:

8. If the queried port is not open, the following output will appear:

8.nc can also view multiple ports at once, for example: