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 can I block all outbound connections?

I need to block my server from initiating any connections to a remote server. However, I still want the server to be able to reply from connections initiated via clients connected. In other words, I ...
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Single iptables on openwrt

I have a router with a fresh openwrt install and local network 192.168.5.0/24. There is a server SERV on 192.168.5.100 (HTTP and some other services). There is also a pptp-client tunnel (visible on ...
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Can I use iptables to temporarily block FTPS (TLS) server brute-force attempts?

There are couple of similar questions like this (e.g. http://serverfault.com/questions/200539/can-i-use-iptables-rate-limiting-to-temporarily-block-ftp-server-brute-force-att) , but I have a slightly ...
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Cannot ping virtual host behind NAT port forwarding

I'm creating network between real Windows 8.1 (R) and two virtual Debian 8 (V1, V2) using VM Ware. V1 has running Tomcat and should have access only to V2 and R should redirect V2 to V1. I used two ...
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How do I block with specific string with IPTABLES?

Want to block this URL STRING with IPTABLES. Need to know specific command. "GET /affiliate/5/campaigns?api_key=duO5gVw3s0&affiliate_id=67647&format=json HTTP/1.0" 404 785 "-" "Dalvik/1.6.0 ...
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What is the best way to limit the IP addresses which can be access from within a docker container?

I have an answer which will limit docker containers to only be able to access a single IP address outside the host. Using this iptables rule on the host: iptables -I FORWARD -i docker0 ! -d 8.8.8.8 ...
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Routing application traffic through interface, not receiving replying trafic

I'm trying to set up a Plex Media Server on a Arch server. However most of the time the server is connect to a VPN and I want the Plex traffic to be routed outside of the VPN interface, tun0 and ...
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Ubuntu router setup guide iptables rules

I'm trying to figure out the meaning of the iptables rules in the Official Guide for Setting up a Ubuntu Router. For example, *nat. I can not find anywhere on the internet that has *nat for iptables. ...
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iptables: How to “override” a port redirect?

My setup is as follows: I have a Linux server with two interfaces, eth0 and eth1. eth1 has an Internet connection through my normal LAN. eth0 is serving DHCP and the interface itself has an IP ...
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Failover on voyage os using eth0 and ppp0 interfaces

Hi I am having problem for failover handling on voyage os. I have a system with eth0 and ppp0 interfaces where eth0 is primary and ppp0 is a secondary path for traffic. root@voyage:~# route -n ...
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Cannot access my port from other systems in same network

My machine is running in Red Hat Linux OS. I have setup a server using apache in port 8060. I am able to access in localhost but not is other systems for the same network. I am able to ping the ...
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Accessing Web UI with Spark1.3.1

I am currently building and deploying spark with standalone mode, including one master node and two worker nodes, on Google Container Cluster. For monitoring purpose (also connecting to master from ...
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Allow only one website using iptables in a linux router [duplicate]

I have a Linux server I'm using as a router for my internal network. I need to block all the websites except one or two using iptables. How can I set this up?
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Redirecting marked packets to Tun device

I have a small program that needs to do various things with a selection of packets, based on various iptable rules. The packets are MARKed this way: iptables -t mangle -d 10.10.0.0/16 -j MARK ...
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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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1answer
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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 [closed]

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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22 views

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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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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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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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
75 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
193 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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66 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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1answer
120 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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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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1answer
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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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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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1answer
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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
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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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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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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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1answer
41 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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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 ...