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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How to white list some ip and all the rest block while having already a DMZ?

I have a Linux machine running which has local ip: 192.168.1.2 connected to a router with public IP 8.8.8.8, now the router 8.8.8.8 has DMZ to 192.168.1.2 As a result spammers, hackers, crackers ...
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Samba ports still closed even with iptables rules flushed and disabled

I’m trying to install Samba on a server running CentOS 6 with WHM/cPanel, and I’m having some trouble with ports. This is a brand new system as of yesterday, and I haven’t yet started locking down ...
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Why do my nat iptables rules not work with marked packets?

System: debian squeeze, Linux server 2.6.32-5-amd64 #1 SMP Tue May 13 16:34:35 UTC 2014 x86_64 GNU/Linux, iptables v1.4.8 lsmod | grep iptable iptable_security 2176 0 iptable_mangle ...
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about CentOS 7 apps & Driver

im using pc for several years but never tried Linux so im quite noob in this field. im using Autodesk maya, Nuke & will learn houdini very soon. i found that linux works faster for this apps so ...
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iptables subdomain port forward

Hello i know i can setup iptables to forward to an other ip when a port is given Example: user enters domain.com and it shows site other user types domain.com:28015 and it connects to a game server ...
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IP tables rule: 0x06/0x02 [on hold]

Can I replace SYN,RST SYN with SYN,RST,ACK SYN,RST,ACK in iptables rule? What will happen If I change it ? # iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp- mss-to-pmtu
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port forward in INPUT level

I want to change the destination port of the ipv6 packet in the INPUT level. So I tried to use ip6tables with nat in the INPUT level but seems this command does not work # ip6tables -t nat -I INPUT ...
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Use Ubuntu Iptable to route public ip to pc in private network

I am currently set up a Ubuntu server as a Router which has two network interface. eth0 -> Connecting to public internet ( 10.10.1.78 ) eth0:1 -> 10.10.1.79 eth0:2 -> 10.10.1.83 eth0:3 -> 10.10.1.81 ...
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3answers
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iptables catches on DENY but not on ACCEPT place prior to it in the chain

I have a weird problem with my iptables firewall: If I set two consecutive identical rules, the first is ACCEPT and the second is DENY, the incoming packet is denied (and logged as such). How is it ...
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6 views

equivalent of iptables rule in ip6tables

I m newbie in the iptables. I have the following iptables rules in the source code of a project iptables -t mangle -I PREROUTING ! -i br0 -p TCP --dport 45 -j MARK --set-mark 0x1000 iptables -t nat ...
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iptables directing traffic through vpn

Networking newbie. I have two interfaces on the host: eth0 and tun0 from my OpenVPN client. The IP addresses are: eth0 192.168.1.22 tun0 10.1.0.8 Question 1 For outgoing traffic by changing ...
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17 views

what the “!” means in the iptable rule

what the "!" means in the following iptable rule iptables -I inacc ! -i br0 -p UDP --dport 69 -j ACCEPT I think is related to the interface br0. I think it mean any interface except the br0 Am I ...
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1answer
23 views

iptables problem in Evil Twin

I've been looking into the Evil Twin method and I found this steps: Creating AP airmon-ng start wlan0 airbase-ng -e PrivateWIFI -c 9 -v mon0 at0 Configuration ifconfig at0 up ifconfig at0 ...
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1answer
21 views

How to block docker-mapped ports with a firewall from outside the host without messing up docker routing inside the host?

I have a docker container running on a host with some port mapped to a port on the host. docker run -d -p 9009:9009 someserver I want this machine firewalled off from the internet except for 80, ...
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22 views

Route certain traffic through tun0 and some through eth0 based on destination IP

I have the following setup, a linux box with 2 physical interfaces sitting between my modem and my router, on eth0 it is set to DHCP and get an IP from the modem, I then run a DHCP server on eth1 so ...
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22 views

Docker tunnel traffic on specific port via VPN

Not sure if this is docker specific or a general networking question. I'm running a Debian Jessie server with serveral docker containers. My understanding is that docker creates a virtual interface ...
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What does the column after destination in iptables overview show?

If I print the iptables overview with iptables -L I get the following output: $ sudo iptables -t nat -L Chain PREROUTING (policy ACCEPT) target prot opt source destination ...
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Why doesn't iptables accept IP address as source?

The command sudo iptables -t nat -A PREROUTING -i eth1 -s ! 192.168.178.30 -p tcp --dport 80 -j DNAT --to 192.168.178.30:3128 fails with Bad argument `192.168.178.30' Try `iptables -h' or ...
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1answer
25 views

Man in the middle using iptables

I wish to test a subsystems which communicates with another subsystems via tcp. I have used the following: "iptables -A OUTPUT -p tcp --dport "+port_number" -j DROP" to stop the traffic on a port ...
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iptables limit number of outgoing connections on a port

I'm currently using the following to limit the number of incoming connections on port 9001 to 900. iptables -t filter -I INPUT -p tcp --syn --dport 9001 -m connlimit --connlimit-above 900 -j REJECT ...
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tcpdump capturing packets only when interface is specified

I have tried 3 different ways of capturing a stream of packets coming into my server. Two of them work and the third does not. I am trying to determine why it is missed by the third approach: ...
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22 views

WordPress won't load unless iptables is disabled

I am running CentOS 6.6 using nginx. WordPress will not load unless iptables is disabled. I tried to add the 9000 port for fastcgi, but that did not work. I am guessing it has something to do with ...
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Use IPTables FORWARD for NFS

I have this topology [R1] -> [F1] -> [Server] I need to pass ssh, web and nfs traffic through F1 to Server using iptables. It's quite easy with ssh and web but I'm stuck with nfs. I have set static ...
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Confusion about the `conntrack` extension of `iptables`

The iptables-extensions manpage has this to say about the conntrack extension (emphasis mine): This module, when combined with connection tracking, allows access to the connection tracking state ...
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27 views

How do I know if certain iptables extensions are available and enabled?

I was reading this: https://help.ubuntu.com/community/IptablesHowTo#Allowing_Established_Sessions It says "If the line above doesn't work, you may be on a castrated VPS whose provider has not made ...
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1answer
17 views

Make traffic go one-way by using iptables

I have a network topology: [C1] - [R1] - [R2] - [C2] C1-R1 network is 192.168.100.0/24 R1-R2 network is 10.9.8.0/30 R2-C2 network is 192.168.200.0/24 What I need to do is to make C2 be able to ...
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90 views

CS:GO SRCDS and iptables (firewall)

I have very strange problem. This morning I wanted download, install and host small server for CS:GO on my VPS. I used this tutorial: ...
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9 views

Port Forwarding using iptables

I have the following problem: I have two servers. I can connect to server A trough the internet. But I also want to connect to server B. How can I use iptables, that if I connect to server A over ...
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29 views

Where do port knocking services listen for incoming knocks?

I'm trying to understand how a port-knocking daemon is able to monitor for knocks, independent of the firewall rules (e.g. accept/drop/reject packets). I've installed knockd, which listens for lets ...
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Limited network connectivity when SSHing through an OpenVPN tunnel

I have setup an instance of OpenVPN with a public IP to allow access to a private subnet on Amazon EC2. I am able to SSH onto machines on the private subnet through OpenVPN but when I do I have ...
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Linux iptables DNAT on incoming packet without conntrack (stateless)

In my linux box 10.20.1.1, i got two UDP apps binded on port 46000 (App A) and 36000(App B) respectively. The apps communicate with two UDP servers bindeded as 10.10.1.1:36000 (Srv X) and ...
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How to redirect traffic to a fixed IP address in Fwbuilder

I'm new to fwbuilder and I want to redirect all incoming wifi traffic to my web server. I tried many iptables command but I've failed so I came up to GUI firewall. Can anyone suggest how to do it?
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Manage NAT using a tool

I have a Raspberry Pi on which I had previously installed Raspbian and am now installing another version on again. It is mainly used to be a test maschine for small programs and primarily as a NAT ...
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OpenVZ cotainer and NAT

I have been trying to days to solve my NAT issue with OpenVZ. I have used their guide on their website/wiki, however I just seem to be unable to get it to work. My Linux box is running on CentOS 6 ...
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iptables: Routing requests to localhost:8080 to google.com

I am trying a simple routing rule that would forward the requests to localhost:8080 to some external address (ex google). I added the following rule : sudo iptables -t nat -A PREROUTING -p tcp -d ...
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Guest as Virtual machine connection to Host

I have guest run on my machine on qemu with configuration: /usr/local/kvm/bin/qemu-system-x86_64 -enable-kvm -cpu host -smp 8 -hda ${TEST_VIRT_ENV_IMAGE} -m 4096 -netdev user,id=user.0 -device ...
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35 views

Forward all traffic from one Linux interface to another?

I have a virtual ESX interface "eth1" that I want to act as a gateway for connections, and then route all of the traffic from these connections out of my "eth0" (WAN) interface. Here are my ...
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Connecting my Xbox 360 to my Raspberry Pi 2 to use an OpenVPN connection

Here is my brief setup: Xbox360 Raspberry PI 2 running ArchLinuxARM (alarm) The raspberry pi's main ethernet port has a cable connecting directly to my main router The xbox has a cross-over cable ...
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36 views

Tor Middlebox: How to check if there is a DNS leak?

I created a tor middlebox. Laptop plus WLAN. Creates a WLAN AP all traffic from that AP should be routed into tor. But I am not sure, if the DNS requests are not leaked. How can I check that? This ...
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tor middlebox: How to route traffic through a socks proxy automatically? iptables routing wlan

I built a tor middlebox. It is an old laptop without screen, creates a WLAN and every traffic on that WLAN is routed into tor. my iptables script: iptables -t nat -A PREROUTING -i wlan0 -p udp ...
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91 views

ssh: connect to host * port 22: Connection timed out

I have CentOS 7 running on a VPS machine and after a computer restart, I could no longer SSH to it. $ ssh -v <IP> OpenSSH_6.6.1, OpenSSL 1.0.1e 11 Feb 2013 debug1: Reading configuration data ...
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Traffic redirection with Rasperry Pi router

I use a Rasperry Pi (running raspbian) as a wi-fi router. It redirects traffic from the Ethernet wire (eth0 - wire + ppp0 - L2TP connection, lx2tp used for it) to wlan0 (USB wi-fi dongle, hostapd used ...
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Connecting router traffic to sshuttle tunnel

I am using sshuttle to get cleanly out of a questionable hotel wifi connection. I have a little travel router and would like to use it as well, briding my laptop's sshuttle connection so I can connect ...
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45 views

CentOS as home network router: IPTables Port Forwarding failure

I have currently set up a home server with a CentOS 6.6 installation on it. The server has two NIC interfaces which I'm using it as my router and DHCP server. Here's a diagram showing the network ...
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22 views

NAT Rule for PPTP Port Forwading

I'm under a very heavy firewall where only very common ports such as 21 and 80 are open. I installed PPTP on my own dedicated server (a Debian Linux) and I`m trying to connect it using Windows, but ...
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https proxy setup in NAT-ed clients

I have network setup as follows: I have 2 PCs. A and B. A is connected to Internet, and A and B is connected by local network. B can also connect Internet through A by NAT setup. In A, the NAT setup ...
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Create a VPN tunnel from ethic to wlan0

I have a lan network of which all internet traffic has to be routed through a openVPN tunnel. I use a RPi, and have setup ethic with a DHCP server, and can connect clients. Currently I use a lan0 to ...
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iptables default rules understanding

What does the last part in the following rules means in term of traffic that is allowed in (dtp:domain, bootps) ? From my research I understand that bootps is bootstrap and dpt is destination port but ...
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IPTables and SIP Proxy-Authorization Header

Is it possible for iptables to check SIP packets for Proxy-Authorization headers, and if there's more than one header in a SIP packet, modify the packet so only the latest Proxy-Authorization header ...
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52 views

port forward from host to libvirt guest virtual machine that is bridged to the host nic

I am having no luck getting access from the outside to a http server running on my network in a Debian virtual machine that was created through libvirt. This what my network looks like: PC1: running ...