Ubuntu Security :: UFW - How To Setup Firewall
Jun 21, 2011
I am a Linux newbie so please bear with me if I sound stupid. I was checking out how to set up a firewall for my system and landed on this webpage: [URL]. But I am so confused with how this ufw application works. What I understand is that once I set it to "default deny" it prevents unauthorized incoming connection but what does it mean when the author says to add exceptions for services I need? When do I need to do that? Also what's an SSH server?
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Jul 22, 2009
Up until recently, as in a few days ago, I was using Ubuntu and had ufw managing the firewall.It's been "recommended" that iptables itself be used. Where do I do the rules go (as in a file) and how do I call those rules at startup?
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Jan 3, 2011
I got Shorewall firewall all Set-up perfect but I'm stuck at 1 last bit. The aim is to let on 2 clients max onto my server. I have the policy setup in webmin as.
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More than 2 clients can get onto the server. The aim is to have it as a ddos protection allowing 100 clients on and a max burst of 10 clients at a time.
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Mar 9, 2011
I am trying to setup a firewall using Centos 5.5. The machine has 2 NICs, one connecting to the ISP/Modem and the other connected to a DIR-655 wireless router. The nic is connecting to the internet port on the router.
I do not want DHCP on the Firewall machine but on the wireless router.
[ISP/Modem]<--->[machine eth0]<--->[machine eht1]<--->[DIR-655 internet port]
IP from ISP Dynamic 192.168.1.1 192.168.1.2
IP's on the DIR-655 LAN will be 124.168.0.0/24 network lets say.
I have setup routes on the eth0 192.168.0.0/24 and 124.168.0.0/24
and added 124.168.0.0/24 to eth1.
I can ping eth0 and eth1 but cannot ping 192.168.1.2.
this setup is not actually connected to the internet so I disabled iptables to try testing the ping and still no good.
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Jan 3, 2011
I currently want to set up a network with 2 Ubuntu servers (mail and web) in a DMZ in order to separate them from an internal network. I want to use a dedicated Linux firewall. This firewall will have 3 network interfaces on it. One network interface will connect to the external router/modem (router and modem in one box), one interface will connect to the DMZ and the other interface will connect to the internal network. The router/modem lets you put, I think it's 1 or 2, interfaces in a DMZ.
But, when I think of any of the dedicated firewall's or servers' interfaces it doesn't make sense to me to put any of them in the router/modem's DMZ (I think it would be better for the dedicated firewall's and the servers' interfaces to have static private I.Ps ie 192.168.2.4 etc right?). What I mean is that even if, as far as the router/modem is concerned, none of the interfaces were in a DMZ, the area where the servers are would still effectively be a perimeter network and with such a set up would still be, effectively,a DMZ, right?
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Dec 18, 2010
Using Windows, I always set a Restrictive firewall policy with a third party firewall. But I also had all ports set to Stealth, something that appears to not offer any security benefits (as I've learned from reading Ubuntu forums). I'd like to learn about best security practices (under Ubuntu) for outgoing firewall protection. I will be using the built-in Ubuntu firewall that is configured via Firestarter. Outgoing filtering offers privacy as well as security benefits. But I thought I needed my ports stealthed to be safe too, so I'm open to learning new things.
I wanted to start a poll to find out how many folks use permissive/restrictive, but no polls allowed here apparently.Could Ubuntu users knowledgeable about firewalls enlighten me on whether I should go Outbound-Restrictive and what applications I will need to allow so Ubuntu "housekeeping" is not affected negatively? I basically just use the internet for software updates, web-surfing and e-mail. One question I have is whether there is something comparable in Ubuntu to Window's "DNS Client" service? I always disabled Window's "DNS Client" and forced each application to request port 53 DNS lookups itself.I only had to allow four programs to accomplish all internet traffic that I engage in. I set all other programs/applications to be either Blocked or to have to Ask for an outgoing connection as needed.Here is my former Windows XP setup:
svchost.exe: allow UDP for ports 53, 67, 68, 123 (time) and TCP for ports 80, 443
Avast: allow UDP for port 53 and TCP for port 80
firefox: allow UDP for port 53 and TCP for ports 80, 443
IE: allow UDP for port 53 and TCP for ports 80, 443
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May 18, 2010
I am learning to setup firewall in my home for that i have selected four system(sys1,sys2....sys4) for testing .I have configured sys2 to act as a firewall with two NIC. sys3 and sys4 are inside the firewall . sys1 is not connected to firewall for testing purpose.
the IP assignments are follows :
sys1 : ( fedora, not connected to firewall i am thinking, But i am not sure )
IP : 192.168.2.1 ,
gateway : blank
dns1 : blank
dns2 : blank
sys2 firewall ,IPTABLES )
code....
what happened is that sys1(not connected to firewall) can ssh to sys4(connected,inside firewall),since the rules are written not to ssh form sys1 to sys4..
then I came to know whatever the request I give, It directly goes as sys1 --> sys4. Not as sys1-----> sys2(firewall)---> sys4 .and the firewall is not filtering and processing anything for both inbound and outbound (i think it's my mistake some where). the requests are directly going inside without firewall.
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May 9, 2011
Can we use iptables as firewall instead of Juniper firewall
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Sep 23, 2010
I have a Suse11 box with 2 network cards:
I have squid as a proxy on the Suse box, and with the default firewall I have to enable masquerading to allow clients on the eth3:1-3 to send and receive mail through the Suse box. I found the Suse firewall completely inadequate (all P2P software/connections are allowed once you enable masquerading) and had to install ConfigServer Security & Firewall. In die configuration of csf I could get my way around getting smtp to work for the eth3:1-3 clients, but pop3 connections does not go through the box. I know I need to allow port 110 and 995 to masquerade of NAT (or something) and then the same for port 22
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Feb 23, 2011
I tried installing F-prot's linux scanner but it doesn't seem to want to install and I am tired of messing with it.
So I am wondering if I even need it or if there is something else.
I am behind a firewall already with my router if that helps any.
I guess I am having trouble understanding why virus protection is less necessary.
Do people not write viruses for linux systems?
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Feb 9, 2010
I want to setup a router with firewall on ubuntu box that will connect windows pcs one serving as outside source and one serving as inside target.
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Aug 3, 2011
I run ubuntu on home pc and am very happy with it. I use internet to surf and to see my email on gmail.com etc. What commands should I give to setup ufw firewall so that only this much is allowed? Also, where can I see if some other connections have been blocked?
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Mar 7, 2011
how can i setup a firewall in my system
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Oct 27, 2009
How do i set up my firewall to allow traffic from iperf?
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Mar 4, 2009
I'm an it student and a newbie in linux OS.
We have this final project that we have to set-up
a firewall in a linux redhat OS which i totally have no idea ..
i did some research but haven't found the right one.
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Apr 5, 2011
I am running squeeze 6 on amd64 i like to know if there is guide how to setup a good firewall for dummies like me
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Jul 24, 2010
I'm trying to get OpenMPI (a parallel programming library) working on my home system. I have just two machines on it now, t61 and quad, connected through a router. (Which is also connected to cable modem for internet.) I can ssh between the machnes, mount directories with NFS, etc. However, I just can't get the OpenMPI to run. The OpenMPI message board suggested that the most probable cause is that the firewall is blocking TCP. I don't know how to tell if that's the problem, and can't find any manual for the SuSE firewall, while the various Wikis &c that pop up in a search don't provide any information that addresses my problem.
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May 16, 2010
Recently I have been working on iptables and trying to understand how to use it. Here's a little script I have written to setup a basic firewall for myself:
Code:
#!/bin/bash
if [ `id -u` -ne 0 ]; then
echo "You need root privilege"
exit 1
fi
PROG=/sbin/iptables
$PROG -F
function sethttp {
echo "Opening http port..."
$PROG -A INPUT -p tcp --dport 80 -j ACCEPT
}
function sethttps {
echo "Opening https port..."
$PROG -A INPUT -p tcp --dport 443 -j ACCEPT
}
function settorrent {
echo "Opening torrent port..."
$PROG -A INPUT -p tcp --dport 52413 -j ACCEPT
}
while getopts "hst" option; do
case "$option" in
h) sethttp;;
s) sethttps;;
t) settorrent;;
*) echo "DOH!"
esac
done
$PROG -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
$PROG -A OUTPUT -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
$PROG -A INPUT -i lo -j ACCEPT
$PROG -A OUTPUT -o lo -j ACCEPT
$PROG -A INPUT -j DROP
$PROG -A FORWARD -j REJECT
echo "Done setting up the firewall! Enjoy :)"
exit 0
OK, this can take 3 arguments that open ports 80, 443 and 52413. And at the end, some default rules are applied. But here's the thing I don't understand:
if I don't give the argument for port 80, I can still view web pages... and also, when I remove the line:
Code:
$PROG -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
Whether I say it to open port 80 or not, I can't view any web pages.
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Jul 20, 2010
I have Ubuntu running on an old PE server. It is running Virtualbox with an instance of Ubuntu inside. The instance is there to run my honeypot.
The server box IP is192.168.1.10. The Virtualbox is bridged with it's own IP of 192.168.1.200. The honeypot daemon is listening to 192.168.1.201 with arpd.
I set up the UFW with DENY. And then enabled only the ports leading to the honeypot scripts which are abound to IP .201. I then forwarded the ports necessary to run VNC to .200.
Here is the UFW status:
buntu@ubuntu-desktop:/var/lib$ sudo ufw status
Status: active
To Action From
-- ------ ----
192.168.1.201 21/tcp ALLOW 21/tcp
192.168.1.201 4444/tcp ALLOW 4444/tcp
192.168.1.201 5544/tcp ALLOW 5544/tcp
[Code].....
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Nov 27, 2008
We have a new Bussiness DSL line with 16 public addresses.What we want is to setup a DMZ to run some services and internet to the LAN. Here's a schematic of what we want:
Code:
Backup Internet Main Internet
connection connection
| |
| |
SDSL Modem BDSL Modem
[code]....
The webserver has the following settings:
IP: 12.34.56.125
subnet: 255.255.255.240
gateway: 12.34.56.126
What IPTABLES rules do i need to setup to "see" all IP's in the DMZ-2 from the internet?
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May 2, 2010
I am attempting to set up a firewall in my home network environment. the rest of the environment is windows, sorry I am attempting now so bear with me. what I have is a cable modem coming in, then my fedora 11 box with 2 nics, then the wireless router and the rest of the network.
everything works fine until I put the linux box in. If I put the firwall in the firewall sees the internet but the wireless router directly after does not. I am doing something wrong with the dhcp I am guessing. I dont want the firewall to give the address to the network I want the router to. I tried to get the firewall to do it (yum install dhcp leafnode) but it kept saying something didn't work right.
so I figure I will let the cable modem give the firewall an ip and the router give the rest of the network their ip's but how do I get the firewall and router to see each other and allow passthrough?
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May 23, 2010
Will I need to actiavte the firewall that comes with Ubuntu since I'm using Transmission?
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Aug 13, 2010
I am new to the Ubuntu/Linix world (less than a week).
I have tried the search, but have had difficulty finding threads on this.
Can someone recommend an excellent firewall to use with Ubuntu?
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Aug 14, 2010
I have a VPS (Ubuntu 8.04 server eition) and as such am stuck with using a software firewall.
i currently have UFW installed.
I would ideally like to have my firewall be a little rude, or rather just not polite. I know what i am asking will break the RFC, but i consider this ok due to the security benefits.
I would like to have my firewall
1) ignore (eg drop without responding)all packets that dont start with a syn flag
2)for all other traffic that is currently blocked, have it dropped (again drop it without responding)
If there are any other rules you can think of i would like to know them. I already have only the services i want open and the rest blocked.
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Nov 4, 2010
I've been using Windows for quite a few years now. I loved the way how I used to set incoming/outgoing rules for my applications. But I'm having hard time doing that in Ubuntu. I tried searching for a good GUI for iptables but I need your help selecting the best. I might learn iptables someday but for the time being I will be using a nice GUI. I'm currently using GUFW, I've tried Firestarter. All I need is a firewall that would allow me to configure rules for my applications.
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Jun 15, 2011
I have set up a Ubuntu 10.10 server. I have been using ssh tunnels to encrypt my web traffic at public wifi. I am trying to make this server as secure as posible so I enabled ufw. I allowed SSH and HTTP traffic in and denied everything else. But when I do that I can not use SSH -D because when I try to visit a webpage it does not load and I get the following.
Code:
uname@mybox:~$ channel 3: open failed: connect failed: Connection timed out
^C
uname@mybox:~$ fclchannel 4: open failed: connect failed: Connection timed out
^C
uname@mybox:~$ exit
logout
What do I have to do to allow ufw to allow ssh tunnels through?
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Feb 13, 2010
i want set up IDS(Intrusion detection system) and Firewall in my home just for learning.. The Goal is learn IDS log and Firewall log..
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Apr 14, 2010
I'm involved in a project to students set up a network security training lab using vmware. I want to simulate (in a very rough way) scanning through a poorly configured router or firewall. The easiest way I can think of to simulate this is to use a linux vmware image with two virtual nic cards to act as a firewall with the attacker on the outside network and a domain controller, web server, and database server on the inside network.
I would like to start students off with a firewall script that exposes everything on their internal network to the attacker. Is there an easy way to (mis)configure iptables to do this?. The model I'm trying to replicate is something like this. Attackers were on a 10.10.x.x network, defenders were on a 192.168.x.x network. As an attacker I could nmap 192.168.x.x and see every machine and every service on the defenders side even if they moved a service to an unexpected location. how I can implement a similar configuration using a linux image as firewalls/routers in vmware?
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May 9, 2010
I have a set of iptables rules generated by Firestarter, and i'm in the process of trying to familiarise myself with iptables itself, but there's one particular rule which is confusing me, perhaps somebody could explain it to me
My INPUT chain reads as follows:
Code:
Chain INPUT (policy DROP)
target prot opt source destination
ACCEPT tcp -- cdns01.plus.net anywhere tcp flags:!FIN,SYN,RST,ACK/SYN
ACCEPT udp -- cdns01.plus.net anywhere
ACCEPT tcp -- cdns02.plus.net anywhere tcp flags:!FIN,SYN,RST,ACK/SYN
[Code]...
Given that the firewall is actually blocking packets, it can't be this simple, so what am I missing?
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Sep 30, 2010
I'm running the firestarter firewall and its been showing the odd ssh attempt quite often. e.g. I've had 4 attempts today, 3 in the last 40mins. I realize that this may be nothing to serious but it's got me curious, aside from having a secure password (which I have) is there anything that else that I can do to ensure that my system is as secure as possible from ssh? I do use ssh within my home network so I don't want to disable it completely.
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