Jack Wallen shows how to open a port in Portmaster to allow safe shell traffic to a desktop computer.
Harbor Master isn’t just a cross-platform network monitor — it’s also a very powerful security tool that can help lock down your desktops and block things like ads, trackers, and malware. I use Portmaster on my primary Linux desktop and I can attest to its ability to block incoming traffic.
I recently had an incident when, for whatever reason (probably because I was feeling lazy and didn’t want to make the trek to my office at the end of the house), I had to SSH to my desktop from another machine on the LAN . I forgot that Portmaster was active and I hadn’t yet created a rule to let that particular IP address through. No matter what I tried, I couldn’t get in. But after I added the allow rule, access through the required port was allowed and everything was fine.
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I would like to show you how to add such a rule to Portmaster so that you too can allow specific traffic to a machine.
What you need
For this to work, Portmaster must be installed. It doesn’t matter which operating system you use, the Portmaster UI is the same across the board. However, I’m going to demonstrate opening the SSH service to an IP address. If your machine doesn’t include SSH, you’ll have to trade that service for something else.
How to open the Secure Shell port
Open the Portmaster interface, which you can do from your system tray if it is already running. In the main window (Image A), click the Apps Overview button.
In the resulting window (Figure B), type sshd in the search field.
Click on the sshd entry and in the new screen scroll down until you see the Incoming Rules section (Figure C).
The first thing you want to do is make sure that Block Connections is in the ON position because you don’t want just any SSH connection to be allowed. Then click Add rule.
From the Select drop-down list, select Allow and then type in the IP address you want to allow over the SSH port (Figure D). When you’re done, click the check mark to save the rule.
One thing I’ve noticed is that it’s always best to add the inbound line before trying to SSH to the machine. I’ve had instances where, after attempting an SSH connection, adding the rule for that IP address didn’t work. However, I’ve never had an instance where Portmaster’s general rules blocked a connection if the rule was added before an attempted SSH login. The lesson here is to always add lines before trying to connect.
And that’s all there is to opening a port with Portmaster. I have found this app to be an invaluable tool, not only for locking down my desktops, but for much better and easier control over what is allowed in and out of a particular system. I highly recommend this free, open-source tool for all your desktops and laptops – and, if they have a GUI, your servers too.
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