The linux telnet command can be used to connect to a TCP port for connectivity testing. For example, a web server may be listening on TCP port 80 for non-ssl http connections. You can test a web server connectivity response using the linux telnet command.
Example 1
Telnet to a HTTP server via TCP port 80
telnet www.websitetest123bbb.com 80Example 2
Telnet to a POP3 server via TCP port 110
telnet www.mailservertest123bbb.com 110