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How to Install Software for TN3270 for Mac OS X 10.7 through 10.10.x Yosemite

Follow the steps below to install software for TN3270 for Mac OS X 10.7 through 10.10.x

Only a beta version of TN3270 is available that functions with the mainframe at this time.  However, it has not been officially approved.  Please follow the instructions below to access the mainframe.

Note: You will need local administrative rights on your machine to install TN3270. A VPN connection is required for mainframe access.

Access Issues? Find your Department Security Administrator (DSA).

1. Download the file.

  1. Download the TN3270 client software at
  2. Choose: Mocha TN3270 for Mac OS X 2.3 (OX X 10.9 - 10.15.x)
  3. Open the downloaded file.
  4. Drag the TN3270 X icon to the Applications folder.
  5. Run the TN3270 X from the Applications folder.
  6. Once TN3270 is open, follow the instructions below to create a session file.

2. Secure your access.

  1. Open TN3270 and close any default window that comes up. Click Cancel.
  2. Click on File then New Session
  3. Enter the host name:
  4. Enter the window title: adcom.
  5. Click the Special box.
  6. In the Port field, enter 1023, and choose SSL for Security.
  7. Select SSL/ TLS Default
  8. Select Negotiate SSL
  9. Click on OK.
  10. Click on Open Connection, and verify the connection works.
  11. Once verified, click File then Save Settings As…, and save settings file to an appropriate location.
  12. If you can't connect, open the Special box, verify the port number, and then try to connect again.
  13. To eliminate confusion, overwrite the old file.
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For more information, contact the ITS Service Desk, (858) 246-4357 or ext. 6-HELP.