Questions tagged [firewall]

Typically software that runs to prevent network traffic from reaching a computer. Also a hardware device that works on a network level rather than running on a single computer.

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1answer
29 views

Running some processes and not others over VPN

I'm looking to secure some apps on macOS using an OpenVPN connection. I want the apps not to work when the VPN isn't active. I can't necessarily track which servers the apps are trying to access, so ...
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1answer
2k views

How to stop Catalina from contacting Apple servers when executing programs?

I'm a software developer and as such I build and run programs hundreds of times per day. I've noticed that since I started using Catalina, after compiling and linking there is a delay (which can be ...
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MacOS port become blocked

I have tried setting up Packet Filter on macOS 10.15.5. I develop software. I am hosting some services via supervisord. It has a user interface on port 9001 running to reset/start/stop services. ...
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Should I buy a Hardware Firewall for my Time Capsule 4th Gen Router?

For my home network, I am still using the Time Capsule 4th Generation Router, from 2011. I realized that I may have overestimated the security of this device, as it apparently does not have a Firewall ...
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HOSTS file & Little Snitch

LS 3.8.2, MacOS 10.13.6 (I'm in 'music', slowly updating). It's great having the option to modify the HOSTS file, but with Little Snitch installed it is not read. (I know the hosts file is not read ...
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Stop iOS app from accessing the internet [duplicate]

There are some apps on iOS that I trust with Health information. These apps are fully capable of working offline. Is there any way to prevent specific third-party apps from accessing the internet on ...
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145 views

MacOS Firewall: 'Do you want the application “Google Chrome.app” to accept incoming network connections?'

Earlier today, I decided to review my MacOS Catlina Firewall settings by deleting my previous application-specific settings, and handle future prompts one at a time. Then when visiting chrome://flags#...
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1answer
71 views

`Do you want the application “main” to accept incoming network connections?` pop up while running Go applications

Every time I am running Go applications on MacOs with this command: go run main.go I get this pop up message: Do you want the application "main" to accept incoming network connections? I added Go ...
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4answers
18k views

Little Snitch reports outgoing connections for AirPlayXPCHelper for wrong subnets?

After upgrading to El Capitan, I've started noticing annoying connections from the AirPlayXPCHelper to 192.168.1.0/24 subnet (my home network isn't in 192.168.1.0/24 subnet, it's in 172.16.0.0/12 ...
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2answers
17k views

Reasons to prefer Little Snitch over the built-in firewall

Every now and then I browse through software you must have on your mac type lists and more often than not somebody mentions Little Snitch as a must-have application. Now what I think that many people ...
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Port Blocking of OSC Messages But Firewall is Off

In my computer I am trying to receive Open Sound Control from a server running internally from an application, the address is '127.0.0.1:57110'. The problem I have is that the OSC seems to be blocked ...
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2answers
44k views

Apple USB Ethernet Adapter has a self-assigned IP address and will not be able to connect to the Internet

Cannot connect MacBook Pro (Retina, 15-inch, Mid 2015) (10.13.3) to the internet through my Apple USB Ethernet Adapter. I am receiving this error under System Preferences/Network: "Apple USB Ethernet ...
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1answer
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How can I turn on the macOS firewall from a script

I'm setting up a new Mac Mini and I am using a script assembled from commands that I've accumulated over the years to set defaults, create directory structures, install software, and otherwise ...
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3answers
4k views

Do pre-built Little Snitch configurations exist and are they shared?

Is it possible to import configurations that have been created elsewhere into Little Snitch? For example, a ready to go basic ruleset for someone who wants to block iCloud's more intrusive features. ...
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Figuring out what is blocking HTTP request on macOS Mojave?

I have a simple http-server running with an index.html, which I'm trying to serve over to another device over LAN. I can access the website in the host computer using localhost and it is recorded as a ...
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How to use pf to route this scenario

Scenario I need pf on a Mac to do this: redirecting any connections to localhost:8080 to a public domain. --> localhost:8080 --> public domain Example The public domain is hosting a nginx server. ...
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1answer
31 views

PF not forwarding incoming traffic on loopback from one port to another

Scenario I have a server listening on port 3000 on localhost. I want incoming traffic to localhost:8080 to be forwarded to that server. My set up: Server listens on port 3000; nothing listens on ...
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pf: Dynamically add rule to nat-anchor

I connect to a Cisco VPN Server and want to share that connection via wifi. Using the macOS Internet Sharing feature, I can only select one interface to share - either my LAN adapter, or the VPN ...
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3answers
74k views

What is the modern way to do port-forwarding on El Capitan? (forward port 80 to 8080)

The old utility ipfw was discouraged in recent versions of Mac OS X and is now gone from El Capitan. What is the modern way to do port forwarding in El Capitan? I simply want port 80 to forward to ...
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1answer
1k views

How do you close an open port in Mac?

Using Netstat (within Network Utility), I discovered an unusual IP address -- this IP address occasionally uses 9 different open ports, including ports 9998 and 9999. I also did an Zenmap scan, and it ...
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1answer
104 views

How to simulate network connections / ipfw on macOS?

I would like all UDP traffic on my localhost to have 1% packet loss, 10 ms propagation delay, 10Mbit/s bandwidth. On other computers I have experience using ipfw something like this: ipfw add pipe 1 ...
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How to allow XAMPP apache through macOS firewall

I am running XAMPP 5.6.37 on Mojave 10.14.6. I am unable to connect to port 80 from another computer when the system firewall is on. It works fine when I turn firewall off in System Preferences. I ...
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17 views

Restrict access to certain websites without VPN

So I'd like to disable some connections to certain IPs and websites without a VPN activated for security purposes so I wouldn't mess up and go to that certain website without a VPN enabled, I wonder ...
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1answer
30k views

Firewall for outgoing connections

Is there a firewall for OSX Lion, that allows controlling of outgoing connections? The built in firewall handles only incoming connections, apparently.
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1answer
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Firewall setup for Python.app incoming connection

I am running a Python programme on my MacBook Pro (Catalina), but everytime it prompts the following information However, in the pane of Security & Privacy preferences, I have set it, How can I ...
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1answer
102 views

Does Little Little Snitch 4 block connections during login?

I have been using Little Snitch for some time now. I think the version I've started to use the program with, was 3.5. Anyway, I remember seeing notifications from Little Snitch about connection ...
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1answer
490 views

How to debug macOS firewall? My application layer firewall (ALF) is not logging or blocking

macOS firewall (alf) socketfilterfw doesn't seem to be running properly on macOS catalina 10.15.2 ... Any ideas on how to troubleshoot / debug the built-in macOS application layer firewall?
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97 views

How to make Little Snitch only block the upload traffic, but not the download traffic? [closed]

I didn't find a way to do that, please help!
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1answer
41 views

How do I trigger Appstore check for app updates manually?

I'm using a firewall and by default, everything, including checking for updates is blocked. In some situations, I'd like to disable the firewall and trigger such checks manually. How do I do that?
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509 views

How to get ufw(8)-like (Uncomplicated Firewall) functionality for macOS firewall?

How can I get ufw(8)-like (Linux Uncomplicated Firewall) functionality for macOS firewall? ufw enables per-IP-address/subnets and per-IP-port configuration. I see no way to do this with macOS sharing ...
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1answer
1k views

How can I block all ports except 443 on macOS Catalina

I realize this will break a lot of built in functionality on macOS as it ships, but for test reasons I want to temporarily block all tcp inbound / outbound ports on macOS Catalina except 443. How ...
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Opening ports on macOS High Serra

Ok so I am having a time trying to get this to work. I have a program that needs to push to another program on port 8080. However I can't seem to get that port to respond. I have checked my router (...
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1answer
163 views

Why is Google Chrome trying to run netbiosd attempting to connect to 192.168.2.255?

I usually don't use Google Chrome, because on my MacBook I'm addicted to Safari. Today when I launched Chrome, it ran netbiosd to connect to the local IP: 192.168.2.255. The local IP does not exist ...
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5answers
38k views

How can I get the exact URLs/requests that a program is trying to connect to?

I currently use Little Snitch to control network traffic on my Macbook Pro, and see what my apps are connecting to. Unfortunately, Little Snitch only shows you the hostname that an app is connecting ...
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582 views

Hamachi: Cannot ping my or anyone else's IP

I have been using Hamachi successfully on my computer for years, but recently, it's been acting up. I cannot ping anyone else on Hamachi. If I click them and hit ping, I just get: Request timeout for ...
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2answers
2k views

I've got an error “This site is blocked due to content filtering.”

The first question is: How it works? And the main question is how to remove spying and traffic sniffing things from the Mac. I've uninstalled Microsoft Corporate Portal, restarted, but it didn't ...
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2answers
134 views

Little Snitch uninstalled properly but Little Snitch Helper still here

Long time ago, I uninstalled Little Snitch with the built-in uninstaller. I also ran CleanMyMac and checked all possible leftovers on Hard Disk: /Library and inside Home Folder: /Library such as : /...
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4answers
2k views

How to launch pf at startup?

I am looking for a pretty elegant way to launch the pf - a.k.a. Packet Filtering - process at startup. Using the launchctl or the pfctl commands, root privileges are required and so it is useless to ...
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1answer
486 views

How to block an IP address?

I am running MacOS Mojave. I am wondering if there is an easy way to block an IP address. For example, I can ping 8.8.8.8 and telnet 8.8.8.8 53. Now, I want to block all access to 8.8.8.8. so ping ...
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10answers
100k views

How to get rid of firewall “accept incoming connections” dialog?

I've accepted this so many times that firewall should already remember it. For example, I get it for Eclipse when starting my java programs in debugging mode ... sometimes this dialog is displayed ...
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1answer
102 views

How can I force all traffic for a single app through VPN / Proxy + Open Source? aka App Firewall?

I'm looking for an app that is fully Open Source OR built-in to MacOS as I am trying to use this for security / privacy (to ensure that particular apps cannot make arbitrary connections) I have ...
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1answer
94 views

Where can i find the source code for the pfctl utility?

I have looked here: https://github.com/apple/darwin-xnu But all i can find is the 'back end' for the pfctl tool, but i am interested in the command-line pfctl tool itself, the option parser and so on....
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How can I connect immediately to VPN after sleep when using PF permanent kill switch?

I have a secure VPN setup that uses macOS’ low-level PF firewall as a permanent kill switch. See https://medium.com/@sunknudsen/setting-up-your-very-own-macos-kernel-level-ikev2-ipsec-vpn-kill-switch-...
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1answer
323 views

use `pf` to allow TCP traffic on specific port (from specific subnet)

So, I've read various posts about how to use both the Application Firewall (apf or socketfilterfw) and the Packet Filter (pf) at the same time. I thought this would be straightfoward since I'm not a ...
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1answer
66 views

Do packets routed to another interface using `pf`'s `route-to` option on macOS actually pass the given interface?

Do packets routed to another interface using pf's route-to option on macOS actually pass the given interface? I've read that pf's firewall rules only applies to packets that (physically) pass the ...
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1answer
107 views

Enable packet filter firewall (pfctl -Ef) temporarily stops all network connection

I've noticed that when re-setting my firewall with a new set of rules, all network communication completely stops for a short time, until it regains with the new set of rules. In fact, it also ...
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1answer
2k views

How to configure MacOS firewall to block outgoing IP ranges?

Recently I was watching a Gizmodo journalist's videos about her experiment with blocking outgoing connections to Google, FB, Microsoft and Apple. I wonder if it is possible to modify MacOS's built in ...
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1answer
580 views

Mac OS X firewall rules to block UDP connection to an external server

Can anybody help to recommand a firewall app for Mac OS X? I'm going to block UDP connection to an external server, and then I need to check whether it switch to TCP connection to the server ...
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2answers
90 views

Why can't I create new network connections after enabling PF with a simple custom ruleset using `pfctl -f`?

Why can't I create new network connections after enabling PF with a simple custom ruleset using pfctl -f? I'm reading the official FAQ tutorial for OpenBSD's PF firewall, also used in macOS. I've a ...
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1answer
796 views

Murus firewall - redirect an ip to localhost web server

Edited to simplify question: using host file, we can redirect a domain (example.com) to localhost: 127.0.0.1 example.com How can we redirect an ip (for example 35.166.133.11) to localhost (web ...

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