How to Get Telnet for MacOS in Mojave or High Sierra

How to Get Telnet for MacOS in Mojave or High Sierra

Get Telnet in Mac OS

Need to use Telnet in MacOS? Well, many Mac users have discovered that Telnet has been removed from modern versions of system software, including macOS Mojave and macOS High Sierra. Presumably this is to encourage using the ssh client instead, but there are many Mac users who need Telnet for a variety of reasons. Telnet continues to be in a valid tool for many systems and network administrators, security professionals, people working with Cisco hardware or towards Cisco certification, MUD enthusiasts, amongst many other purposes.

Accordingly, this tutorial will detail several different ways to get Telnet back in modern versions of Mac OS system software. We’ll cover installing Telnet with Homebrew, restoring Telnet from a prior system software release or backup, compiling Telnet from source, as well as a few alternatives to telnet.

This article will assume that you have experience working with the Terminal and command line, since Telnet is entirely command line based.

Installing Telnet in MacOS with Homebrew

By far the simplest option is for Mac users to install Telnet through Homebrew. Of course this means you will need to install Homebrew on the Mac first, but if you’re advanced user that spends time in the command line you’ll likely appreciate having Homebrew for other reasons since you

  1. Install Homebrew on Mac OS if you haven’t done so already – if you already have Homebrew skip this step
  2. /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

  3. Use Homebrew to install telnet with the following command:
  4. brew install telnet

  5. Hit Return and let Homebrew download and install Telnet to the Mac
  6. When installation has complete, you can run Telnet as usual:
  7. telnet server-or-ip-address

One simple way to test that Telnet is working properly after installation is to connect to the goofy Star Wars telnet server, which plays Star Wars in ASCII art:

telnet towel.blinkenlights.nl

You’ll know Telnet is working when you are greeted by Star Wars rendered in ASCII characters (and yes seriously, it’s the full movie).

Telnet Star Wars server and movie

Installing Telnet in MacOS Mojave & High Sierra via Older MacOS Versions or Backups

If you happen to have access to a Mac that is running a prior version of MacOS (Sierra or prior), or you happen to have an older MacOS system software backup laying around from Time Machine or otherwise, you can actually just copy the old binaries from that computer or backup to your modern MacOS installation, and telnet will work just fine.

With Mac OS and Mac OS X versions that include telnet, you will find Telnet at the following location (thus serving as a reference for where to find the binary in the backups:

/usr/bin/telnet

The telnet binary is tiny weighing in at only 114 kb, so this is a quick simple task.

Copying that telnet binary into the following location in modern macOS releases, including MacOS Mojave 10.14 and MacOS High Sierra 10.13.x, will allow telnet to run on the new system software releases:

/usr/local/bin/

At that point you can run the ‘telnet’ command as usual.

Another option which requires more caution is to request the telnet binary from a trusted coworker or trusted friend who is running MacOS Sierra or prior. All they need to do is zip up and send you their /usr/bin/telnet binary file. Do not try and find a random telnet binary zip file from the internet since it could be compromised or otherwise untrustworthy. It’d be a good idea to use md5 hash or sha1 checksum on the original telnet binary if you’re going this route.

By the way, if you’re relying on binaries of telnet from Sierra or earlier, you might also be interested in grabbing ftp as well, which is also removed from modern macOS releases, but is located at the following location in prior MacOS builds:

/usr/bin/ftp

Again you’d place the ftp binary into /usr/local/bin/ on new versions of system software.

For those wondering, while Telnet (and ftp) has been removed from Mojave, High Sierra, and presumably anything moving forward, MacOS Sierra remains the last version of system software to include Telnet by default, while any MacOS / Mac OS X release prior to Sierra also includes Telnet and ftp, including El Capitan, Snow Leopard, Yosemite, Mountain Lion, Mavericks, Tiger, Cheetah, etc.

Telnet Alternatives for Mac: SSH, Netcat

Of course there are some alternatives for Telnet, depending on what you need to use telnet for in the first place.

For remote connections, ssh is the new standard as it is secured, and both the ssh server and ssh client are available by default in all modern versions of MacOS system software. Simply, connecting to a remote IP with ssh would look as follows:

ssh [email protected]

For simple testing of network connectivity, or for testing of an open / listening port, netcat can often fulfill the same needs that telnet provides. For example, you can confirm that the connection to the aforementioned ASCII Star Wars server and port 80 works with the following netcat command string:

nc -vz towel.blinkenlights.nl 80

Remember that netcat for this purpose requires specifying a valid TCP or UDP port number of whatever the host protocol is.

Netcat and telnet

Restoring Telnet to MacOS Mojave & High Sierra by Compiling Telnet from Source

If you don’t want to use Homebrew for whatever reason, you can also compile Telnet yourself from inetutils source. As a prerequisite you’ll still need to install the Mac OS command line tools to be able to accomplish this, however.

First you’d download the latest inetutils package from gnu.org:

curl -o http://ftp.gnu.org/gnu/inetutils/inetutils-1.9.4.tar.gz

Next you’d decompress the tarsal:
tar xvzf inetutils-1.9.4.tar.gz

Now change into the appropriate directory:
cd inetutils-1.9.4

Issue the configure command to begin:
./configure

When configure is complete, make from source:
make

And finally, use make install to complete the installation of inetutils and telnet:
sudo make install

Personally I think using Homebrew is easier, plus there are many other great and useful Homebrew packages available. If you’re familiar with compiling from source and you are this far, you’ll almost certainly appreciate having Homebrew anyway.

What about Telnet for iPad and iPhone? Telnet for iOS!

Just to cover all bases, there are also telnet clients available for iOS. How practical this is for you likely depends on your particular device and what your intention with telnet is, but a free option for iOS is iTerminal and an excellent paid option is Prompt. Using ssh and telnet from an iOS device can be a challenge without an external keyboard though, so you might want to connect one to your iPhone or iPad before going that route, and realistically this is a better option for the iPad simply due to the larger screen. Of course iOS is not MacOS however, so this is sort of off topic.

Alright so that’s a pretty comprehensive guide to getting Telnet in modern MacOS releases, but if you know of another method, or another approach to getting Telnet in MacOS High Sierra or returning Telnet to MacOS Mojave, share with us in the comments below!

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