When I do a network scan for open ports on my MacBook Pro, I can see the following open TCP ports below. Are these 'standard' open port for a personal computer of this type? Should I be concerned? Are there any ports I should close for security purposes? If so, how would I do this?

Open TCP Port: 631 ipp
Open TCP Port: 3413 svnet
Open TCP Port:  17500
Open TCP Port:  17501
Open TCP Port:  17600
Open TCP Port:  17603
Open TCP Port:  18800
Open TCP Port:  21324
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    I have never used a macbook, but if it were my machine, I would be concerned that there are any open ports, and I'd go figure out what each one was and whether it's necessary. – Mike Ounsworth Jan 30 '19 at 2:22
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    There cannot be any direct answer to this question unless you provide information about what apps are using these ports. Check out the purpose of these ports as mentioned by @MikeOunsworth, and then disable the ports if they are not being useful for any of your applications. – tech_enthusiast Jan 30 '19 at 2:38
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    Generally speaking, open ports are not in themselves a danger. It’s the application they connect to that’s of concern. Ideally on a workstation computer you should have few to none open, because there is not usually a thoughtful isolation of services as one would have in a server environment. If applications are running as your login user and listening for requests, if they can be exploited they probably have access to all your documents, etc. – nbering Jan 30 '19 at 5:04

Open ports are specific to each network interface. If you performed the scan from the MacBook itself, then chances are that you are seeing open ports that are exposed to localhost only, and not to the local network. It may be that a port is reachable from the same computer, but not the local network.

To view which processes use which ports, you can use the following command:

sudo lsof -i -n -P

This will print all ports and connections. Those with LISTEN are ready to receive connections.

On my MacBook only TCP ports 8021 and 29754 are open. You seem to have more open ports, but whether that's good or bad isn't clear without more details.

MacOS has a built-in firewall to block incoming connections. You can find the settings under "Security & Privacy".


**Theoretically speaking just having an open port is not bad. It actually depends on the vulnerability of the application listening to this port. **

That being said, having more ports open, increases the probability of your system being discovered, and the chances of being exploited increases with the increase in the number of vulnerable applications listening to those ports.

Once you identify the open ports on your system you should ahead and find out more information related to the application listening to these ports. And ask the question:

Is this application vulnerable, in the event, I leave the port open? If you research, compels you to answer yes, then it is probable that having it open might be bad.

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