A firewall is a program that controls the incoming and outgoing network traffic on a system. Use this tag for all questions related to firewall configuration and operation.

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9
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4answers
30k views

Set some firewall ports to only accept local network connections?

Basic firewall question: How do I set up the firewall on a system in a LAN so that some ports are only open to connections from the local area network, and not from the outside world? For instance, ...
1
vote
1answer
2k views

Fedora firewall with UPnP?

I'm using Fedora 15 and Transmission BT client. Transmission can't open ports unless the firewall is disabled. I searched some posts that said add 1900 to the trusted ports, or via a iptable rule: -...
3
votes
1answer
329 views

Setting up the firewall for amule on OpenBSD 4.7 gateway

I'm trying to properly setup the firewall on my gateway (OpenBSD 4.7) using pf to allow amule (on 10.0.0.104) to operate properly as discussed here: Now I know pf has changed a bit from OpenBSD 4.7 ...
2
votes
1answer
4k views

How to stop firewall from writting logs to /var/log/messages?

I'm running OpenSUSE 11.4. The problem is that I can set easily what to log, but not where to log. And currently the same logs are written to /var/log/firewall and /var/log/messages. I still want ...
4
votes
2answers
2k views

What tools do I need to intercept and change an incoming packet on a WP2-Personal wifi hub

Which tools should I research into to intercept a plain text packet, edit it and then continue it on it's way. I am using Ubuntu 11.04 and Backtrack 5; my wifi is WPA2-person encrypted. I need to edit ...
6
votes
2answers
6k views

How to limit P2P/torrent traffic on an OpenWrt 10.03 router?

We have a WRT160NL router with OpenWRT 10.03, and a 60-70 Mbit connection (from ISP, don't ask why). This router can do 30-35 Mbit on ethernet(i mean cable)..ok! There are ~7 PC's using this Wireless ...
1
vote
1answer
615 views

Why does Firestarter say my firewall is active but ufw status shows it as inactive?

I am using Linux Mint and am having the following issue. Firestarter tells my that my firewall is active and it does indeed seem to be active. However when I type "sudo ufw status" into the terminal, ...
3
votes
1answer
231 views

iptables infographic

Is there an infographic somewhere that describes the logical flow of iptables? Specifically, I'm looking for something that diagrams which point in the process ip_conntrack applies.
0
votes
3answers
905 views

EBtales not working

I wanted to go a little bit further and install EBtables (the 2-layer filtering and routing table). The purpose of it was to only allow the minimal necessary(IPv4 and ARP). To test it I ran: ebtables ...
10
votes
4answers
13k views

Fail2ban block with IPtables doesn't work on Debian Lenny. [moved ssh port]

I've recently decided to do some security maintenance. I saw my logs, and there were some tries against my SSH server. At first, I moved away the SSH port from the default 22. After it, I read ...
2
votes
2answers
11k views

Problems setting up TigerVNC and firewall

I have a box running a fresh install of Fedora 15. I've installed TigerVNC server on it and client on my Windows machine. I've added -A INPUT -m state --state NET -m tcp -p tcp --dport 5900 -j ACCEPT ...
6
votes
2answers
1k views

Configuring a vncserver so it's only accessible from my ssh tunnel

Since I use vnc through an ssh tunnel, is there any way I can block the open vnc port that the remote machine is listening on without it affecting my ability to use the ssh tunnel? Both machines are ...
2
votes
3answers
596 views

Port monitoring on GNU/Linux based NAT router

I am using a Ubuntu machine as a NAT router. How can I find out the following: the ports on which the LAN machines are listening or communicating (both tcp and udp); which local machines have ...
3
votes
1answer
3k views

iptables/pf rule to only allow XY application/user?

I think there is no iptables/pf solution to only allow an XY application on e.g.: outbound tcp port 80, eth0. So if I have a userid: "500" then how could I block any other communications then the ...
1
vote
1answer
1k views

I can't figure out how to install Firestarter Fedora

I am feeling stupid. I have been searching for 3 hours with no success. I installed Fedora 14 and tried to do yum install firestarter but the package was not found. I also tried from a GUI and found ...
7
votes
1answer
988 views

Opening port 80 but remain secure

I have a standard installation of Ubuntu 10.04, and have installed the LAMP stack so I can do some web development locally. On my router I have opened port 80 so I can develop with external services ...
13
votes
3answers
45k views

iptables: allow certain ips and block all other connection

How do I allow certain ips and block all other connection in iptables?
2
votes
2answers
816 views

Is there any PF log parser for FreeBSD

I am runing FreeBSD 8 stable with PF as firewall, I am looking for any tool for parsing PF log's.
3
votes
1answer
189 views

Linux App that monitors log and add rules to iptables

I used to use a linux software that monitors logs like http, ssh, etc and if it detects that someone is trying to use brute force, it blocks that ip by adding a rule to iptables. I forgot what that ...
2
votes
2answers
2k views

tun0+ iptables rule

I'm trying to figure out what that + sign means in a rule such as this: -A FORWARD -i tun0+ -j ACCEPT I'm pretty positive it relates to vpn. I noticed a /dev/net/tun interface and a tun0 in ...
-1
votes
1answer
2k views

How to block HTTPS site using RHEL Squid?

I want to block HTTPS sites using Linux Squid server. How can I do this?
2
votes
4answers
669 views

What does this iptables command do?

Does iptables -I INPUT -j ACCEPT open all ports?
15
votes
4answers
14k views

Is there a way to find which iptables rule was responsible for dropping a packet?

I have a system that came with a firewall already in place. The firewall consists of over 1000 iptables rules. One of these rule is dropping packets I don't want dropped. (I know this because I did ...
3
votes
1answer
409 views

1000 iptables entries on CentOS?

I just got a new dedicated server with CentOS and I'm trying to debug some network problems. In doing so, I found over one thousand iptables entries. Is this the default on a CentOS system? Is there ...
1
vote
2answers
1k views

iptables rule for local network with free internet blocking unrequested connection from internet to server?

I have a home server (with slackware 13) with a eth0 for the local network and a eth1 for the internet (cable modem with dynamic ip). While I do want to learn more about iptables I am still on the ...
5
votes
4answers
494 views

Is it possible to simulate “no external access” from a Linux machine when developing?

Sometimes I upload an application to a server that doesn't have external internet access. I would like to create the same environment in my machine for testing some features in the application and ...
3
votes
3answers
290 views

Turning an old computer into a network firewall

I have an old Dell Dimension with two ethernet cards, and I need to turn it into a firewall. I've tried FireStarter and IPCop, but I don't think I'm setting them up right. Here's the setup that I'm ...
0
votes
2answers
148 views

Where to handle packets between clients?

"Server": 192.168.1.1 I want to "theoretically" disable that the clients can "ping" each other. Can i use an iptables rule for it? e.g.: iptables -A FORWARD -m iprange --src-range 192.168.1.2-192....
1
vote
1answer
2k views

IPTABLES rule for separating users

I have an OpenWrt 10.03 router [ IP: 192.168.1.1 ], and it has a DHCP server pool: 192.168.1.0/24 - clients are using it through wireless/wired connection. Ok! Here's the catch: I need to separate ...
1
vote
2answers
764 views

squid (reverse proxy) configuration

I would like to configure squid in such way, so that only specific (public) ip (reverse proxy), could connect to the server, but I don't know how... can someone tell me how to do this?
6
votes
3answers
466 views

SpamAssassin Under Linux VPS

I am getting bald with this guys: On a Linux VPS (CentOS), I have setup a mail server (Exim+Dovecot+Clamav+SpamAssassin) but scanning mail for spam using SpamAssassin is proving to be a challenge. I ...
-1
votes
1answer
2k views

How can I open port 21 on a Linux VM?

I need to open port 21 on a Linux (CentOS 5) virtual machine I have. I have tried several Google solutions, but none are working. I was wondering if someone could tell me how to do this. Below is ...
1
vote
1answer
902 views

Could not connect to host 127.0.0.1: Connection refused

Could not connect to host 127.0.0.1: Connection refused. - I am getting this error message on ktorrent on slackware 13.1 and the torrents cannot start. I tried to reconfigure the ktorrent prefernces, ...
2
votes
1answer
576 views

How would I go about getting UPnP working on a Slackware server/firewall?

I'm a long time fan of Slackware and I've always had a machine serving as my main server/firewall with the latest version installed. I have it now but I'm struggling to find information on how to ...
7
votes
4answers
8k views

Debian: Which firewall for a newbie?

I have to install a firewall on my server (so without X Server). It's a debian lenny. If it is possible, I want to avoid the use of iptables. Is there a way to install/configure a firewall for a ...
5
votes
3answers
858 views

tunneling VNC/rdesktop over ssh

I'm having a friend behind a firewall, with a windows computer. I'm having a Linux machine at home which is not behind a firewall. I want to have an rdesktop connection to his machine, without using ...
5
votes
1answer
1k views

ipfw : Traffic Shaping

I'm not sure what but it seems like I'm doing something wrong... my objective is to be able to limit some of my traffic, to be exact www traffic. One of my clients os running what's called a webproxy,...
3
votes
3answers
190 views

Firewall change control

At the moment I'm using a Python script to generate iptables rules. Each set of changes gets committed to a git repository before deployment so there's a trace of who changed what and why. What tools/...
3
votes
1answer
347 views

Learning about iptables: Is this Slicehost example any good?

In preparation to eventually launch my first website, I've been playing with Ubuntu Lucid Server in a VM on my WinXP machine. I've been alternating between the Linode and Slicehost tutorials/articles ...
2
votes
6answers
498 views

Recommend a reading for learning Linux firewalls configuration for beginner? [closed]

I am using Linux at home and want to be able to configure firewall. I would like to understand what I am doing not just copy paste some rules from internet :).