What is the best way to remotely access my PC from my laptop?

I was interested in such activity but found some solutions.

One woud be to use ssh clients like Putty with tunneling to access your home devices, for that I used some services like ngrok, remote.io etc.

For accessing full desktop screen ssh with vncserver and client should help you.

Agree with that, heterogeneous is definitely non-trivial, and a lot of firms only recently (well, past decade or so) started to make use of it, due to a few factors, and individuals are pretty much exposed if they don't consider it carefully.  

Regarding SSH, I can think of an alternate semi-solution that is sometimes helpful. The technique is Reverse Port Tunneling, also sometimes called Remote Proxy Tunneling, it's described here: 

https://gist.github.com/markjlorenz/6206454?permalink_comment_id=2954806

Although not overly complicated, it's still more effort, and requires a server in the middle (e.g. in cloud) to make it happen, and gains a bit of benefit since no inbound ports need to be kept open.

Agree, hopefully any reader can see there's a lot to consider when thinking about such stuff. We might have also scared away any future spammers on this thread anyway : )

What is your motivation to access the PC from a MacBook?

Remoting across your own network (i.e. home) is not difficult. Remoting over heterogeneous networks adds complexity and security risks especially if you are going it alone.

I opened port 22 on my home firewall to enable SSH access from the Internet. In a 24-hour period, I had 100K scans of the IP and 50K logfile of failed attempts at logins.

If the goal is to consolidate files so they are accessible from one place. Think of using a file service. They do the heavy lifting, you gain the benefits. Choose a service that protects your data. I'm in Canada. I store data on Canadian servers to prevent the long arm of the US law from accessing.

shabaz said:

We will know the risks and will mitigate, but 99% of users won't, especially those asking such questions

And I'm all for responsible disclosure of information/guidance - it's so necessary these days, especially when easy to use tools such as shodan exist. 

That can be done, although just make sure whatever you're using doesn't balk when some scanner tries a legitimate HTTP request at the port ;). Some VPN solutions are designed to do this to some extent by design (e.g. SoftEther).

Setting up a port-knocking sequence is another way to make it less obvious, but necessitates doing things in a certain order and timing.

- Gough

(should also mention, obviously, (might not be obvious to some) the "server in the cloud" should at least be IaaS virtual server, not rented hardware. 

We will know the risks and will mitigate, but 99% of users won't, especially those asking such questions, and will not realize it's opening up access to vulnerabilities right to their PC or Pi etc., or will substitute with older or vulnerable hardware or software (near-decade-old old home routers for instance are not unusual). Even the basic ancient SYN attack is still one of the most popular techniques, and that requires no hacking skills.
As an example of old hardware, the home router I was given from the provider I'm using (BT) is a decade old, they've never offered me a free replacement, I've had to buy my own.

The only time I've ever successfully persuaded a client (in their isolated lab) to ever allow remote access, was by using a particular secure VPN protocol trusted by banks, and even then, only open up the VPN connection when required, which entails a remote server, which was in the cloud, so that it could be explicitly shut down at all other times. This remote server was like a stepping stone to establish the VPN between two machines. Using different port numbers was useful, but on it's own is just extending the time until an attack.

Using this technique, we could reduce the attack footprint, since we could place a firewall rule to only allow traffic from a specific IP address + port combination, reducing the risk from random servers, since the cloud server had a known public IP address (this is easy to configure of course), and that known IP could be definitively shut down at all times apart from when the connection was required, since it's in the cloud. We guaranteed what specific device would connect, because once its public IP address was known, it could be entered into the server in the cloud. This was as good as we could manage, using up-to-date hardware/firmware. 

We were reasonably comfortable with this setup, but only on a limited temporary basis to get through some work and then dismantle/unconfigure it all.

Gough Lui said:

Sometimes, you just meet networks that are firewalled and won't allow you to connect to non-standard ports, so it may pay to also use a different VPN server that can also handle that.

That can be a benefit of a roll your own solution, sometimes it can help to go against the RFCs and re-use a port that's normally meant for say, http traffic :D

I have a variation of this ... in my case, I needed to also pay for a VPS because the home machine is behind a double-NAT (i.e. carrier grade NAT + router NAT). If you're behind just one NAT, port forwarding will work, but being behind two is pretty much game-over.

As a result, I have a Pi (or equivalent) maintaining a Wiregard tunnel (UDP ftw) to my VPS which is the "lucky" endpoint with a static IPv4. I can then connect to the VPS from my client and access the network as normal at home (subject to how one writes their iptables firewalls). I do have the SSH tunnel and autossh as a backup.

I've got WOL set-up, so the machine at home often sleeps (so can be woken quickly by WOL). But such a set-up has many hoops ... and takes much work to get working the way you want. Sometimes, you just meet networks that are firewalled and won't allow you to connect to non-standard ports, so it may pay to also use a different VPN server that can also handle that.

Your servers will get probed, brute-forced on the regular. Software bugs can also happen. Keeping everything up-to-date is vital.

- Gough