Configuring a Mac VPN client
Setting up a VPN using OS/X's native VPN client is relatively straight forward.
Step 1: To start, go to the "System Preferences" icon.
Step 2: Once you have expanded this, select the "Network" icon from the "Internet & Wireless" section.
Step 3: In the bottom left-hand corner of the network page, click on the "+" (Create new service) to start a new service wizard.
Step 4: Click on the "Interface" icon. From the drop down list, select "VPN".
Step 5: From the "VPN Type" drop down, select "L2TP over IPSec". Give this new service a meaningful name.
Step 6: Now you must specify an address for the VPN. You also must specify a valid VPN user name.
Step 7: Next, select "Authentication Settings". Here you will enter the password for the VPN user you created and your VPN's preshared secret key.
For more information about creating VPN users, go HERE
For more information about preshared keys, go HERE
Step 8: Now, from the Network section, select "Advanced". Once this page is opened, select the checkbox for "Send all traffic over VPN connection". The other three Session options depend on your organizational requirements. Best practice is to close a VPN tunnel if it is not being used, for security purposes. Click "OK" and then "Apply".
With everything configured, you should now be able to connect to your VPN by clicking on "Connect".
If you have configured everything correctly, your status should change to "Connected". An address for you VPN should appear.
Now that you have established a VPN tunnel, you access your virtual machines by either using "Remote Desktop Connection" (for Windows) or PuTTY (for a Linux). Let us use RDP as an example.
With RDP launched, you will be prompted to enter the address of the virtual machine you wish to access. You will be using the address that was assigned from the pool you defined.
You will also need to supply a valid user and password for that Windows instance.
Once you have entered everything, a connection can be made. You will probably receive a certificate warning. Connect anyway.
If you have made the connection, you will be presented with a terminal console for the server you wish to access.
When you are finished using your VPN tunnel, be sure to close it.
For information about troubleshooting VPNs, go HERE