Keeping 3 Macs At Different Locations Identical

Question

Background: I have several Macs, but 3 I need to keep identical in terms of data - docs, files, folders, email and such (the other Macs are generally work stations for staff). I am a businessperson with an office, an office at home and a MBP I move around with. I have sensitive client data I need access to day and night (whenever the call comes or the email arrives). What I do and have done for years is zip everything new to myself and update each computer nightly - manually. Waste of time and getting OLD! Cloud based worries me as if any of my client data got into public domain, I could have real issues.
Question: What is the most practical, efficient and safe way to have the 3 crucial Macs get the daily data and update themselves automatically (without having to do the daily manual routine) so that where ever and when ever I need it, on whichever computer I'm on,I have current data?
Do I need a dedicated off site server? If so, how would each Mac auto update itself?
Any suggestions/advice most appreciated.

Answer 1

First, a general comment. Others have suggested that you use a cloud storage solution. That would be easier, but you would be entrusting what you describe as "sensitive client data" to strangers with no real responsibility for it. That's unacceptable in my opinion, but you may feel differently. If you do, then my proposed solution isn't worthwhile for you. On the other hand, my way of doing it has the advantage that your data will be no less private than it is already.
To set up an SSH server, you need to do three things:
(1) Open the Sharing preference pane in System Preferences, and check the box labeled "Remote Login."
(2) Open the Network preference pane, select your connection to the Internet, and click the Advanced button. Select the TCP/IP tab. You'll see a pulldown menu labeled "Configure IPv4." Most likely, it will be set to "Using DHCP." If so, make a note of the IP address, the subnet mask, and the router address. In the menu, select "Manually," and re-enter those same values. If "Manually" is already selected, you can skip this step, but still note the IP address.
(3) Assuming you're behind an NAT router, set it to forward TCP connections on port 22 to the IP address of your server. If your router has an active firewall, you must also create a rule to allow this traffic. I can't tell you specifically how to do this, because I don't know what kind of router you have, but they're mostly pretty much the same.
See if you can get that far, or if this is too much trouble for you. *If you do it right*, your email and other Internet functions won't be affected.