Mac OS X: About Remote Login, OpenSSH, and Telnet

With Mac OS X 10.0.1 or later, your computer uses OpenSSH for remote login instead of telnet, rlogin, and rsh services. If you have a specific need for telnet, it may be re-enabled as explained below.
This article has been archived and is no longer updated by Apple.
The Sharing pane of System Preferences includes a checkbox for "Allow remote login." Installing the Mac OS X 10.0.1 Update (no longer available) or a later version of system software on your computer changes the behavior of remote login.

Mac OS X 10.0 behavior

Enabling the "Allow remote login" option turns on telnet, rlogin (remote login), and rsh (remote shell) services. You can then connect remotely to your computer by using a client application for any of these services.

Mac OS X versions 10.0.1 to 10.1 and later

Enabling the "Allow remote login" option turns on OpenSSH service. You can then connect remotely to your computer by using an SSH client application. Mac OS X 10.0.1 provides OpenSSH-2.3.0p1. For more information on OpenSSH, open the Terminal utility and type "man ssh" after the prompt.

    1. To install a software update, choose System Preferences from the Apple menu and click the Software Update icon. You may check for updates manually or on a schedule.

    2. If you have installed an open source version of OpenSSH, the 10.0.1 Update will overwrite it. This may apply to later versions of system software.

    3. Depending on system software version, you may experience a delay when you enable the "Allow remote login" option. The delay is due to the time it takes to start up the OpenSSH service. Click the checkbox only once. Clicking multiple times may result in the box appearing checked even if the service is off. You may correct this symptom either by restarting the computer or by using the Terminal utility to delete the file /var/run/

Enabling telnet, rlogin, and rsh in Mac OS X 10.0.1 and later

Important: Telnet, rlogin, and rsh send information (including passwords) over the network unencrypted. OpenSSH provides greater security. You should only revert to telnet, rlogin, and rsh if your network environment requires them.

You must be logged in as an Admin user to follow these steps. After each step in which you type a command, press the Return key.
    1. Open the Terminal utility.
    2. Type sudo pico /etc/inetd.conf
    3. Type in your admin password.
    4. Press Return.
    5. The file inetd.conf will open in the pico text editor. Using the arrow keys to navigate, scroll down until you see the lines for:
    6. Remove the pound "#" character from the line of each service you want to re-enable.
    7. Save the file (press Control-O), press Return, and exit pico (press Control-X).
    8. Choose Restart from the Apple menu.

When the computer has restarted, the services you enabled should be available.
Published Date: Oct 7, 2016