I would like to check if given server is online and given service is active -- or maybe even simpler, if given port is open. 

Something like this:

```
port_check my_server 22

```

or

```
service_check my_server ssh

```

And I would get a binary answer -- yes/no, meaning everything is OK, or there is no connection (server is down, or the service is not active).

I have to run this tool from ordinary user account (non-root). The question is -- what is the tool? Thank you in advance for help.

**Edit**: please note, I have to get binary answer, which means any interactive tool, or tool that tries to log in first is no good. It should be basically a ping but for any service.