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Questions tagged [firewall]

a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts

A firewall is a device or set of devices designed to permit or deny network transmissions based upon a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass.

1255 questions
129
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5 answers

See configured rules even when inactive

I'm wondering if it's possible to get UFW to list the configured firewall rules even when it's not enabled. I only have ssh access to the server at this time, and I don't want to enable UFW if there's not a rule configured allowing ssh. However,…
Bryan
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112
votes
11 answers

Uncomplicated Firewall (UFW) is not blocking anything when using Docker

This is my first time setting up an Ubuntu Server (14.04 LTS) and I am having trouble configuring the firewall (UFW). I only need ssh and http, so I am doing this: sudo ufw disable sudo ufw reset sudo ufw default deny incoming sudo ufw default…
ESala
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100
votes
0 answers

How do I see which ports are open?

I am running a web server on a machine with Ubuntu 11. Everything is accessible from the local network, but not from outside. What can I do to check to make sure the appropriate ports are open? I am relatively new to Ubuntu and server management, so…
CoderJK
  • 1,129
97
votes
3 answers

What is MASQUERADE in the context of iptables?

In iptables many times I see the target MASQUERADE. What is that? I searched and found lots of things. But I need someone to explain to me what MASQUERADE is in an easy to understand way? An example (taken from this answer) is: sudo iptables -t…
Mohammad Reza Rezwani
  • 10,706
82
votes
13 answers

How to control internet access for each program?

I would like to use a software to control which program may connect to the internet. I know that this behaviour is associated with the word "firewall", but some Linux users are very upset if somebody demands a Personal Firewall. I don't want to…
guerda
  • 1,191
82
votes
5 answers

Why is the firewall disabled by default?

Why is ufw firewall included in Ubuntu, when it is not enabled and pre-configured by default? Most users don't even know it is there, because no GUI frontend is provided.
6205
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5 answers

How can I open a range of ports in ubuntu using (g)ufw

I have to open up a group of ports. Adding the single ports to (g)ufw was easy enough but I can't work out how to open the range 11200-11299. How do I do that?
Pieter Breed
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60
votes
2 answers

how do you create an app profile for ufw?

Ufw has a command that lists out profiles to which you can further explore their profile definitions $ ufw app list And $ ufw app PROFILE {app profile title} I was wondering how you can create a profile for an undefined program, like virtual box…
Miphix
  • 1,078
59
votes
5 answers

How do I know if my firewall is on?

I installed Firestarter, and configured my firewall. But I'm in doubt : On boot, I sometimes see a [FAIL] marker, and to the left, I guess it was something like "start firewall". I can't be sure because the message is seen for less than a second,…
paercebal
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51
votes
7 answers

What are the risks of NOT using a firewall (home computer)?

Since a password is required to be a superuser (to install and modify programs), what are the risks to not use a firewall under Ubuntu ? More particularly if I am using a NAT router ?
riimzzai
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50
votes
3 answers

How can I make a specific set of iptables rules permanent?

Is there a "best practice" or standard to make a few iptables rules permanent? I mean: automatically applied upon a system reboot? I am using a VPS with Ubuntu Server 10.04 LTS (Lucid Lynx). Thank you. BIG EDIT: I don't want ANY rule to be persisted…
J. Bruni
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46
votes
5 answers

How to block internet access for wine applications?

How can one prevent specific or any wine applications from accessing the internet? When using certain applications under Windows, they were trying to access the internet from time to time without any obvious reason. I was able to prevent that…
YSN
  • 2,359
44
votes
4 answers

How to configure UFW to allow IP Forwarding?

I have UFW, OpenVPN and Virtualbox installed on my home server. I have a host-only network for my virtual machine guests (vboxnet0) set up with the IP range 10.0.1.0, and another IP range of 10.0.0.0 configured on the other end of the OpenVPN…
Stephen RC
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43
votes
4 answers

How do I turn off the firewall in Ubuntu 12.04?

How do I turn off the firewall in Ubuntu 12.04? Thanks for the answers. The reason for turning it off was twofold: I often cannot make a wireless connectin to internet and get the server is unable to connect message or I get a message that…
dustbindiva
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41
votes
3 answers

How to allow remote connections to Flask?

Inside the system, running on virtual machine, I can access the running server at 127.0.0.1:5000. Although the 'remote' address of the vm is 192.168.56.101 (ping and ssh work fine), I cannot access the server with 192.168.50.101:5000 neither from…
Ilya Smagin
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