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

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54
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3answers
149k views

How do I see which ports are open? [duplicate]

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 ...
50
votes
7answers
4k views

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 ?
45
votes
4answers
21k views

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.
34
votes
10answers
26k views

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 ...
29
votes
3answers
18k views

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 ...
24
votes
3answers
2k views

What automated intrusion notification/detection setup is good for home desktop use?

I've been using Linux for quite a while now and I always feel the need to have a passive software / script setup which can alert me of any suspicious network activities like scans, failed login ...
23
votes
4answers
230k views

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 ...
22
votes
3answers
39k views

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 ...
21
votes
5answers
8k views

Is there a preinstalled or automatic firewall?

Does Ubuntu come with a preinstalled or automatic firewall? If not, do I need one? I've read some articles about the advantages of linux over other operating systems about security (no need to have ...
20
votes
4answers
17k views

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 ...
20
votes
8answers
12k views

Alternative to Little-Snitch app-firewall?

I'm trying out Ubuntu. Been a Mac user. I like ubuntu a lot but I'm uncomfortable not having an app-firewall that reports what connections are being made to the internet. I find it unnerving to not ...
17
votes
3answers
79k views

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 ...
14
votes
6answers
5k views

Does spyware exist for ubuntu?

Someone I know said he had put spyware on my computer. Is he talking crap? I've been using Ubuntu 12.04 for nearly 3 years now and I've never seen any type of spyware, remote keyloggers or RATS ...
14
votes
4answers
12k views

How can I open a range of ports in ubuntu using (g)ufw for use with membase?

I have membase (membase.org) installed and I have to open a bunch of ports in order for the cluster to function Adding the single ports was easy enough but I can't work out how to open the range ...
14
votes
1answer
34k views

What are ICMP redirects and should they be blocked?

After enabling ufw and the Tiger security auditor, I see warnings saying: The system accepts ICMP redirection messages What are ICMP redirection messages? Should they be disabled for security ...
12
votes
8answers
3k views

Is a Firewall really necessary these days? [closed]

should I install something like gufw?
12
votes
1answer
20k views

How can set these iptables rules to run at startup

I usually run my iptables rules whenever I login. From the terminal I type ; sudo sh firewall.sh Setting up my sister's computer, I want to give her some basic firewall protection. She wont be ...
12
votes
1answer
21k views

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 ...
12
votes
4answers
24k views

How can I block ping requests with IPTables?

and stealth specific ports?
10
votes
1answer
83k views

How to open a port?

I have ubuntu 12.04 and I'm not able to allow certain port in my firewall. So I basically said I will allow everything but it's still not working. Please help. nmap on this machine from other machine ...
10
votes
1answer
965 views

Precautionary security measures for a home user? (firewall, antivirus, etc)

I just recently made the switch from Windows to Ubuntu, and I'm just a little paranoid when it comes to security measures. I've looked around and from what I've read, security is not as big a concern ...
10
votes
4answers
3k views

Reverse Firewall or Application Firewalls?

Firewalls are typically employed to prevent bad "packets" coming in from the outside world. But these days we are mostly behind routers and a lot of that danger is mitigated by the router. The danger ...
10
votes
3answers
2k views

Replacing my firewall rules

I've had an init script for many years that configures iptables for me and it has worked like a champ until now. After upgrading from 10.04 to 12.04 I started having firewall problems where the ...
9
votes
2answers
8k views

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 ...
8
votes
2answers
7k views

How to set up an Ubuntu 10.04 machine to accept ssh requests only from within the local network?

I am about to install 10.04 (from bare metal to replace 9.04) and I want to set it up so that I can shh into the machine, but only from other machines on my local network. (I.e., I want to reject all ...
8
votes
2answers
8k views

What is MASQUERADE in the context of iptables?

In Iptables many times I see the target MASQUERADE. What is that. I searched and find lots of things. But I need some one explain me what MASQUERADE is in a so easy way? **If you bring an example ...
8
votes
2answers
16k views

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 ...
8
votes
2answers
10k views

“FirewallD not running” error when trying to install a printer

When trying to add my printer in a fresh install of 11.10 I get this error message. What does it mean, and what do I have to do? It worked fine in 11.04 (with hplip).
8
votes
3answers
1k views

Can I be notified about blocked connection attempts?

My computer is running Ubuntu 10.10 and I would like to know if there is a firewall that actively informs me when a certain program is trying to access the internet or when a connection attempt is ...
8
votes
3answers
37k views

How to enable ufw firewall to allow icmp response?

I have a series of Ubuntu 10.04 servers and each one has ufw firewall enabled. I have allowed port 22 (for SSH) and 80 (if it's a webserver). My question is that I am trying to enable icmp echo ...
8
votes
2answers
7k views

What do UFW's audit log entries mean?

I'm sometimes getting a lot of these AUDIT log entries in ... [UFW AUDIT] IN= OUT=eth0 SRC=176.58.105.134 DST=194.238.48.2 LEN=76 TOS=0x10 PREC=0x00 TTL=64 ID=32137 DF PROTO=UDP SPT=36231 DPT=123 ...
7
votes
2answers
8k views

Can't connect to PPTP VPN with ufw enabled on Ubuntu 14.04 with kernel 3.18

Suddenly VPN disconnected and can't reconnect no longer on kernel 3.18.1, so I try to install kernel 3.18.2 but my problem still exist. But I can connect to VPN with 3.14 kernel easily. The output of ...
7
votes
6answers
9k views

UFW firewall still blocking SMB despite adding rules

I have an Ubuntu PC with ufw firewall (GUI version). I have added the preset Samba service, in and out, and even tried adding the ports manually (135-139, 445, UDP and TCP, in and out), but it still ...
7
votes
1answer
19k views

MySQL server not accessible from remote machine

I have installed MySQL server in my local Ubuntu server (11.10). I can't connect to the server from a remote machine. When I tried:- nmap localhost , It shows the following PORT STATE SERVICE ...
7
votes
4answers
19k views

What rules to use for UFW?

I've decided to enable the UFW that comes with Ubuntu just to make my system even more secure (especially after watching a video of a person whose computer actually got infected!), and I've enabled ...
7
votes
1answer
392 views

Why are certain things able to get through ufw firewall?

I should say up-front that I am TOTALLY new to Linux, Ubuntu, and the technical side of networking. I am setting up Ubuntu on a server computer and have learned a bit about configuring the ufw ...
7
votes
2answers
7k views

UFW is not logging how do I troubleshoot?

I have set logging to high. I am not seeing any log messages. I do see the empty ufw.log file. No messages in dmesg
7
votes
3answers
1k views

How can a non-geek set up a proper firewall?

Maybe a non-geek that knows of the existence of a firewall is already some kind of a nerd. If you have been a windows-user then it was rather easy to set up a firewall (I don't know if it was a good ...
7
votes
2answers
3k views

How to restrict user's access to the internet for time intervals?

I want that one of the users (not in the sudoers list) have Internet access from 14:00 until 16:00 and from 17:00 until 18:30. Is it possible? Can I set different time intervals for different week ...
7
votes
2answers
1k views

UFW rules don't work with docker

I have a 12.04.4 server, and I have enabled ufw, and have tried to block port 8080. However, it is still open. $ sudo ufw deny 8080 Rule added Rule added (v6) $ sudo ufw status numbered Status: ...
7
votes
1answer
611 views

Getting Dynamic firewall from Fedora 15 into Ubuntu?

Just tried out Fedora 15 and noticed the pre-installed firewall application that I found much easier to use than any other previously tried out firewall manager. Definitely miss it at my Ubuntu ...
7
votes
6answers
3k views

Do I need a firewall for my desktop? [duplicate]

I don't have a router, but I mostly use my desktop for online shopping and torrenting. So, do I have to enable the firewall? I hope not, because I'm really dumb and I don't think I will be able to ...
6
votes
1answer
10k views

What GUI firewall manager should I use to replace Firestarter?

Apparently Firestarter is no longer maintained, and it does not have any options in its interface for handling the connection to a VPN. Right now, my VPN does not work if my Firewall is activated. I ...
6
votes
2answers
5k views

How do you view all of the banned IP's for Ubuntu 12.04 via the command line?

I can't seem to find a quick command to just view all the banned IP's on the server. Or is there a file I can just edit? I'm guessing fail2ban is the one that inputs all the IP's to ban. Where do I ...
6
votes
2answers
10k views

What could be the cause for these strange UFW block entries in my syslog?

I've recently noticed a large number of recurring UFW blocks in my syslog. This surprised me as I have no UFW rules set: $ sudo ufw status verbose Status: active Logging: on (low) Default: deny ...
6
votes
1answer
395 views

Securing Riak using Shorewall Firewall

I want to set up a Riak Cluster for a Web project. However, I want to secure this cluster so that only My Web Server(s) can access Riak Cluster. Basically, I will have one or more Web Servers and 4 ...
5
votes
4answers
13k views

How to deny an ip address from connecting to my system?

Is there a way to deny an IP address from connecting to my Pc? Is there a way to deny an Ip from connecting to specific Port?
5
votes
2answers
9k views

System log error when running Firestarter configuration program

Running latest Ubuntu ver. 11.04. Using Firestarter firewall configuration (ver.1.0.3). When Firestarter is run, an error message is returned, "Failed to open the system log. No event information will ...
5
votes
2answers
342 views

Is portfowarding to my localhost on my personal Ubuntu computer secure?

After installing Lamp on my personally Ubuntu computer, I am running a application that requires to connect to the web and send SMTP mail; for example paypal needs a www address to notify successful ...
5
votes
3answers
9k views

Why UFW has to be (re)started at boot time if it's only iptables rule manager?

README from source package says: When installing ufw from source, you will also need to integrate it into your boot process for the firewall to start when you restart your system. Depending on your ...