Iptables is a module that provides the Linux operating system functions of firewall, NAT and logging of data traveling over a computer network.

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udp client sending ICMP “port unreachable” when receiveing messages from the server

(Note: I moved this question from StackOverflow, because it's to be considered off-topic there, better fits here, and still unsolved) I have a udp client using luasocket, basically doing this (with a ...
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Should my server ever need to directly communicate with the NAT gateway?

What I mean by ``directly communicate'' Does it ever need to receive packets with the gateway's IP address as the source IP address, or send packets with the gateway's IP address as the destination ...
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iptables configuration on Windows Azure (CentOS 6.5) for endpoint load-balanced set

I created 2 VMs (CentOS6.5) on Windows Azure for Postgresql database and HA cluster, everything works fine except when I set iptables service on, the endpoint load-balanced set is down. for security ...
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Firewall init script

On Debian, what is the best way to start an iptables firewall script : /etc/init.d/firewall_script.sh in /etc/network/interfaces, add post-up /etc/network/if-up.d/firewall_script.sh Do you check ...
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mirroring traffic with iptables doesn't work

i want to mirror specific traffic to ip 192.168.200.1 i use this solution : Mirror Port via iptables but when i enter following command, error occurs: iptables –I PREROUTING -t mangle -j ROUTE --gw ...
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IPSet with IP6Tables ERROR

Can someone please solve my headache and tell me how to fix this? [root@www ~]# ip6tables -I INPUT -m set --match-set blacklist6 src -J DROP ip6tables v1.4.7: Couldn't load match ...
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Iptables rules to only whitelist SIP providers

I have an Asterisk box sitting behind an ADSL router/modem. There are no other services on the Asterisk box, just telephony. I am getting a lot of traffic which I think are SIP probes. I've ...
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Allow internet access to intranet only users using Nginx on Ubuntu

I need to allow some users who only have access to the intranet to access one specific internet site. I'm doing this by using Nginx as a reverse proxy. To test this, I would like to block all internet ...
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Redirect ports with iptables

I need to do redirect port 443 on all interfaces to 8080 on one interface using iptables on a box with 2 NICs. I also need to block pretty much anything else on those interfaces. Here is my iptables ...
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Block all outgoing traffic for a User running Wine apps

Good day, I'm using a lot of WINE apps under Linux which work just fine, but one thing I am specifically looking for right now is to block their access to the internet (outgoing), with exception of ...
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317 views

block network access to a domain (ubuntu)

I have a few ubuntu servers in various geographies. I want to block all outgoing connections from all ubuntu machines (all processes) to several domains, e.g. www.server.com. I know iptables can block ...
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outgoing ssh fails from only one machine on lan to outside network

I have multiple servers in my LAN (which I'll refer to as Box1), and they are all able to make outgoing SSH connections, except one that stopped recently, which I'll refer to as Box2 (actually, I'm ...
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Wifi sharing over eth0

There are a lot of tutorials how to share network connection with your usb wifi adapter and I tried lots of them but it is still not working. Can you please help me with my problem. Here is my network ...
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217 views

Cant connect to eth0 after wlan0 sharing with iptables

I wanted my Ubuntu server to act as a wifi hotspot. So I set up hostapd to allow wifi connections. I then setup dnsmasq to provide the DHCP settings. I then added the following iptables rules, so ...
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OpenWRT and iptables: redirect all traffic from ip1 to ip2

I'm aware of other questions with the same topic, but I couldn't get it to work. I'd like to forward inside my local network all traffic from ip1 to ip2. Only from inside the network, no outside. I ...
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How to block all ports except 80,443 with iptables? [duplicate]

Blocking all ports(in and out) is easy but it's hard with the word "except". I don't know any rules that satisfies the condition. PS: I know this question is nothing new. But in fact, I didn't find ...
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Limit incoming connections using iptables per IP

I need to limit access to some port per IP. Let's say 5 connections per minute - not more. I've seen iptables recent, connlimit and limit, but all of them are not fitting exactly what I need. ...
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How to forward traffic using iptables rules?

I am new to iptables and I have been doing Google searches for a few days now without finding a good solution to this problem. I have computer A with a public ip address (say 192.0.2.1) that can ...
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543 views

Asterisk server firewall script allows 2-way audio from incoming calls, but not on outgoing?

I'm running an Asterisk PBX on a virtual machine directly connected to the Internet and I really want to prevent script kiddies, l33t h4x0rz and actual hackers access to my server. The basic way I ...
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Equivalent iptables command on OS X 10.9

I want to redirect the tcp traffic temporarily to a custom port. On Linux, I use the following command: iptables -t nat -A OUTPUT -p tcp --dport 1935 -m owner \! --uid-owner root -j REDIRECT and to ...
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47 views

Add IPtables rule by script at the request of another computer

I wonder, is it possible to make an script, which adds rule in iptables by request from other pc? I mean, script "knows" what to do, but addres for rule comes from request. And how do you think it ...
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463 views

Block All Traffic and Allow from Defined IP only in IPTABLES

I want to create a gateway firewall for my network . I want to block all the internal traffic on gateway and allow it from two computers only . On gateway --> eth0 is network card in gateway PC ...
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289 views

Bitbucket SSH and iptables

I'm a newbie in iptables to be honest. I have some basic rules. Everything is blocked by default. iptables -t filter -F iptables -t filter -X iptables -t filter -P INPUT DROP iptables -t filter -P ...
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465 views

Iptables mark incoming packet - vpn routing

I have connected my home to my workplace for out of house backup reasons through OpenVPN. The connection is working nicely. At work I have 5 fixed IP addresses. Now I would like to assign one of ...
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Combination of NAT, DHCP, and OpenVPN on lubuntu 14.04

Okay, so I've got a set up, where eth0 my internal IP address (192.168.1.3) it has been configured as my default gateway using the iptables this sudo sysctl -w net.ipv4.ip_forward=1 sudo ...
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iptables: Is it dangerous to filter by source port?

I would like to run a stateless firewall setup and I currently have the following rules: #Do not track any packet *raw :PREROUTING ACCEPT [0:0] -A PREROUTING -j NOTRACK COMMIT #Actual firewall rules ...
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151 views

IPTables and PPTPd

I'm trying to add the line -A POSTROUTING -i ppp0 -j MASQUERADE to my IPTables in order to allow VPN to have access to the entire internal and external network (eth0, and eth1), but when I try to ...
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340 views

iptables --append FORWARD required for routing between NIC alias IPs?

I have an ubuntu box with a single NIC. In order to bind a number of services (like apache, dnsmasq, etc), I have bound them to different alias's (e.g. eth0:0, etc), some of which are on completely ...
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272 views

How to add iptable support to the kernel (for Wheezy/Sid release)

I am running an ARM processor (similar to the raspberry pi) and my kernel doesnt natively support iptables. If I run apt-get install iptables, it successfully installs but NAT tables are unable to be ...
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IP forwarding from one interface to another on Debian 7

Background The Debian 7 that I run has the following interfaces wlan3 == Internet connection 85.5.48.64/24 wlan2 == act as an AP (hostapd) 192.168.5.1/24 I run the following settings on the ...
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Firewall rule for local, interactive users?

I want to add a firewall rule that applies to a local interactive user. The intention is to clamp down the box, and only allow web and mail related connections, and update service connections. On ...
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Run shell script on incoming network package

I have a bit of a weird question. I have a setup where a Raspberry Pi (running that debian) sits next to a door in my office and is connected to the network. The idea now is that if somebody inside ...
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379 views

How do I fix these iptables?

I am trying to setup my networks firewall, and am having trouble because i keep getting kicked out of SSH because of mistakes. Here's what I currently have: # Custom Rules iptables -F iptables -X ...
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Mirror Port via iptables

I have a dedicated Linux (Debian 7.5) root server, with a number of guests set up. The guests are KVM instances, and get network access via bridge-utils (NAT, internal IPs, use the host as a gateway). ...
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Why is change to iptables not taking effect?

Im trying to setup OpenVPN to use Tor as a proxy in Liberte. When I run openvpn as root, I get the following response: Tue May 13 15:15:18 2014 Attempting to establish TCP connection with ...
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Help with iptables

I recently installed Oracle Linux 6 on a home server, and I've been having trouble with allowing ports past the firewall (iptables). I've tried adding ports with the command iptables -I INPUT -p tcp ...
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Iptables error :libipt_cgroup.so doesn't exist while using net_cls.classid in net_cls cgroup subsystem

In kernel document doc/cgroup/net_cls.txt, it introduces the function of net_cls.classid, and show an example of netfilter (iptables) using this tag to perform actions. the command of iptables is: ...
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Why are these iptable rules keeping me from browsing the internet? (allowing 80,443,53)

This is for my home machine. Here are the rules: Chain INPUT (policy ACCEPT 0 packets, 0 bytes) num pkts bytes target prot opt in out source destination 1 ...
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iptables: Allowing multicast & other traffic on LAN, not to WAN

I have a Linux 3.10 machine functioning as a NAT router between the wlan0 LAN and the eth0 WAN. I would like to allow all communication between machines on the LAN (they are trustworthy) and allow ...
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175 views

iptables eth0 wlan0 bridge not working

I am trying to allow an embedded system to share the wireless of my laptop. The embedded system is an A20 Olinuxino Micro running Debian and my Laptop has Ubuntu 12.04. I tried this which has worked ...
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Transparently proxifying certain devices on the network

I'm using my computer as wireless access point and router to my home network using hostapd under Ubuntu 14.04. I want to transparently proxify certain wifi devices in the network (identified by their ...
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380 views

How to share ppp0 to wlan0 with redsocks

I can't understand the meaning of this: I have a USB modem along with a USB Wifi router, and I use redsocks for ppp0. Then I want to forward the incoming connection from Wifi to redsocks. I have ...
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1answer
269 views

Ports in Linux vs Windows

I'm studying for a security class. I know that ports in Linux are tied to a process. So if I wanted to close/shutdown a port, I'd end the process that's using it. So if I'm in Windows, what's ...
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How to check/adjust SSH server on embedded board

I'm currently having difficulties connecting to an embedded board from my Linux machine through ssh. The embedded board is a FOX G20 V with a Linux OS. I've tried to connect to the board through ...
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Redirecting internal traffic to gateway's port-forwarded external endpoints directly to intranet destination

There's an intranet and CentOS-powered gateway that provides connectivity for intranet devices. Typical port-forwarding in gateway's iptables ruleset looks like this (TCP version is provided): ...
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Granular routing with iptables and iproute2 over VPN

On a host at my house I have a host for a VPN that I need for a couple of purposes. Living temporarily in Japan, it functions as a NAT for some devices so I can still use my NETFLIX and some other ...
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iptables blocking all traffic even with ports opened

Simple as I can put it: I can't access my servers with iptables enabled, with default rules. Need to disable iptables to get access. Trying to find the cause. Only difference in setup type is layer3 ...
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Can't connect to web server from outside my network

I have a Debian-based server that I would like to be able to access from the Internet (no domain name yet, I'm just trying to get it working for now). I already have port forwarding set up on my ...
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bridge does not forwarding packets centos

I am using CentOS 6.5 64 and use xen to create a virtual machine (CentOS) ifconfig [root@CentOS ~]# ifconfig eth0 Link encap:Ethernet HWaddr 08:00:27:54:B3:FA inet6 addr: ...
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Conntrack/NAT's port mapping for a specific port breaks whenever that port's service is shutdown for too long. How can I fix this?

Linux Gentoo 3.13.6-hardened-r3 #1 SMP Sat Apr 12 09:17:25 EDT 2014 x86_64 Intel(R) Core(TM)2 CPU 6300 @ 1.86GHz GenuineIntel GNU/Linux hardened with grsecurity and selinux with a strict policy in ...