Telnet has been removed from the newest version of Ubuntu (Bionic) in order to help keep your server secure. If you need to use Telnet, GreggHost recommends doing so on your own computer.
Telnet is a discontinued network protocol for remotely logging in to another computer or communication device. The Telnet protocol has no security features. All communications, including passwords, are sent across the wire in plain text while using Telnet. As a result, for any command involving secure data, SSH is the sole option. Telnet should only be used for the most basic of testing.
Telnet, as previously stated, should never be used with passwords or sensitive data because it is insecure. You can, however, utilize Telnet to test the essentials of your GreggHost services.
Testing a connection to a mail server
You can test the connection between your local computer and the mail server if your mail client isn’t connecting properly.
Instructions on how to find your correct mail servername can be found in the following article.
How can you figure out what your mail server’s name is?
To test your connection, use SSH or the Windows command prompt to run the following command:
$ telnet imap.dreamhost.com [server] 143
If the connection is successful, it will respond as follows:
I’m going to try 18.104.22.168…
I’ve established a connection with imap.dreamhost.com.
‘]’ is the escape character.
* All right [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE STARTTLS AUTH=PLAIN AUTH=LOGIN] [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot is ready to go.
Ctrl +] on your keyboard will exit the Telnet session. The command prompt will now display as telnet>.
To end the session, return to the terminal and type the word ‘close.’
Telnet can also be used on a Windows PC (assuming you have enabled it). Details can be found in the following articles.
Commands for Telnet
On Windows, use Telnet.