UPDATE: JAN 20, 2018
macOS provided built in nc(netcat), therefore you can use nc in your command line as you do above in tutorial above.
No need to install telnet anymore!
After I’ve upgraded macOS to high Sierra (10.13) the telnet was removed. So, in this topic we’ll bring the telnet back again.
First one you need a homebrew, if not let’s type this command to install them.
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
Second, install telnet using homebrew
brew install telnet
Wait until install finished.
Playing with telnet
Now we have telnet installed so let’s try to play with them.
telnet cis.poly.edu 80
Enter the http request header.
GET /~ross/ HTTP/1.1
and you’ll get output like this.