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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Secondary NIC: what all can I do?

I was loaned a NIC which I promptly installed in my F16 workstation just to 'play' with it (using iptables and stuff). Other than forwarding packets from the new NIC to the old NIC using various ...
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Home network to accept only certain MAC addresses from LAN

I have Ubuntu 10 as router with WAN(eth0) and LAN(eth1). How can I restric eth1 to accept only packets from certain MAC addresses and drop the rest? I am also about to setup DHCP to certain MAC ...
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Blocking a device from all network traffic, but with specific exceptions

I have a router that runs Tomato, so I have access to iptables. There's a device on my network with an IP address of 192.168.1.100. I don't want it to send data to the Internet except for a very ...
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2answers
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OpenWRT: iptables rules will be deleted automatically

In my OpenWRT instance, I have added iptables rules in the Input filter table, but the problem is when I turn on my system I found that the rules are deleted. What can I do so that the rules are not ...
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1answer
101 views

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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330 views

Drop IP fragments of a certain protocol

When conntrack is active, the iptables stack never sees a fragmented IP packet, only the reassembled one (source), so the -f test never matches. If I want to block any fragment I could set ...
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Nginx works on my linux machine but is not accessible from other computers in my local network

In my LAN network I have a server with Scientific Linux (RedHat or Fedora based distro), I've done yum install nginx but the welcome page is not accessible from other computers in my network. When I ...
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1answer
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OpenWrt: how to give wlan clients @ 10.x Internet access via gateway @ 192.168.1.254

I want to isolate guests connecting to my Wi-Fi to the 10.0.0.x subnet, while giving them Internet access. The OpenWrt router is at 192.168.1.48 ("wifi" interface has 10.0.0.1) and my gateway is at ...
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Iptables port mapping from two PCs to one

We have 3 PCs, two of it are connected to internet (both of it have 2 NIC) PC1: eth0 - 1.0.0.1 (external IP) eth1 - 172.16.0.1 (internal IP) PC2: eth0 - 1.0.0.2 (external IP) eth1 - 172.16.0.2 (...
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5k views

DD-WRT Setting Up Guest Network

I have a router on which I installed DD-WRT firmware. I am trying to set up a virtual interface to use as a guest network. The guest network should be on the 192.168.8.0/24 subnet while our LAN is ...
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iptables equivalent in windows-xp,win7?

I want to do port forwarding in win7,what's the iptables equivalent in win7?
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What do these numbers mean in the output of iptable-save?

In the output of iptables-save # Generated by iptables-save v1.3.8 on Sun Mar 14 19:42:45 2010 *filter :INPUT ACCEPT [328764:37367248] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [324693:28884726] COMMIT # ...
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290 views

Logging communication between two VMs

I'm trying to set up "malware lab" described in this paper. So far, I've set up Windows guest system, adding one Host-only Network adapter, and setting this (sorry if the names aren't exactely correct,...
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1answer
862 views

Ubuntu IPTables allow only allow 1 country

So I've been looking around on the net for a script that will drop all traffic to all ports except the http(80) and https(443) ports, and then only allow traffic on all other ports from country x (...
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287 views

Cannot retrieve http sites when using OpenVPN, but https sites work just fine. Why?

I am using a VPN provider that uses OpenVPN. I don´t wont any other traffic leave my computer so I have set up my iptables like this: iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P ...
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540 views

Expose a Reverse SSH Tunnel on the Remote server

I set up a Reverse SSH tunnel from my home computer to my work server: ssh -f -N -R 19999:localhost:22 remoteuser@server To connect to my home computer I have to first log in to the server and then ...
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1answer
905 views

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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What does this iptables rule mean: tcp flags:0x06/0x02 TCPMSS clamp to PMTU?

What does this iptables rule mean: tcp flags:0x06/0x02 TCPMSS clamp to PMTU? Doing iptables -vnL on my DD-WRT router shows the following rule in the FORWARD chain: TCPMSS tcp -- * * 0.0.0.0/0 0.0.0.0/...
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Connecting to an SSH server behind a NAT

I am having trouble connecting to an SSH server behind a NAT on an ubuntu workstation. I've installed openssh package(both the client and the server) and forwarded port 22 through the NAT and tried to ...
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1answer
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How to block incoming traffic on a virtual interface?

How do I block all incoming traffic on eth0:0 but keep eth0 open? What I've tried is this: iptables -P INPUT DROP iptables -A INPUT -i lo -j ACCEPT iptables -A INPUT -i eth0 -j ACCEPT But this ...
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Bandwidth limit by Port on iptables

What iptables function would I use to bandwidth-limit all traffic on port 566 to 2KB/s? I'm confused about exactly how to do this.
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586 views

How to send out some traffic via my vpn connection

I had a working setup where I could access all my work resources which are accessed via VPN going via my server previously however at some point recently this stopped working for no obvious reason. ...
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OSX: Mimic Ubuntu IP Masquerading via iptables with ipfw

Good day, I am attempting to replicate a setup I have between a router and an Ubuntu PC, and have the same setup working on my MacBook (10.6, Snow Leopard). First, I have a router that has a USB ...
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645 views

Different routing rules for a particular user using firewall mark and ip rule

Running Ubuntu 12.10 on amd64. I'm trying to set up different routing rules for a particular user. I understand that the right way to do this is to create a firewall rule that marks the packets for ...
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1answer
921 views

How do you add a MAC-based routing whitelist with DD-WRT and the OpenVPN client?

I have an OpenVPN client set up on my DD-WRT home router which maintains a VPN into my workplace. Slight problem: I don't want random lusers who access my wireless AP to have access to my company's ...
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1answer
1k views

How to block access to a website on Lucid Lynx?

I am trying to block a few websites on a lucid lynx, I tried editing /etc/hosts and that blocks access via url but the site still open if I enter the ip on the browser, how can I block ip access also? ...
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What Iptables rules need I to forward a windows remote desktop connection?

I have this situation: network mask. 255.255.255.0 router/gateway: Ubuntu server (only command line, no gui) with internal lan ip 192.168.0.2 and a dynamic dns on the external ip Windows pc on 192....
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1answer
182 views

Troubleshooting port forwarding

I'm trying to run a web server from my home network, but I have some difficulty reaching my server from the WAN. If you have an idea where the problem could lie, or need more information, please let ...
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1answer
70 views

Netfilter/tc rule to separate SSH and SFTP traffic?

When I connect to my server (RasPI 2 with Raspbian) remotely, I want my interactive SSH sessions to always have priority over any running SFTP sessions. Also, SFTP sessions should have less priority ...
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585 views

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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827 views

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 10.10.1.2:...
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1answer
2k views

VPN does not reconnect (cannot resolve host address)

maybe someone can help me: At the moment i am trying to configure a fail-safe VPN connection to a commercial VPN provider on a virtual machine. This is working fine, until my router wants to reset my ...
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OpenVPN won't connect from remote location

I set up OpenVPN on a linux machine in my basement. I'm able to connect from my Windows 8.1 machine without an issue when I'm connected to the local network. In this instance, I set the config file ...
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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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120 views

When writing an iptables save file by hand, how does one calculate the packet-counter and byte-counter values?

I am attempting to write a 22MB iptables rule-set file, the very kind that is generated with the iptables-save command, except endlessly long. Understandably, this takes a prohibitive amount of time. ...
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295 views

Traffic not being forwarded through NAT

I have a router which provides internet access using NAT, and a client Linux box (A) which is connected to this router on eth0. This Linux box also has a wlan interface, wlan0; what I would like is ...
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2answers
5k views

How to route specific traffic through OpenVPN?

I'm running a server at home with rtorrent and apache2. I would like to route my rtorrent traffic via OpenVPN and since im kinda new to OpenVPN and iptables i would like to have a user friendly guide. ...
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3answers
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Source Based Policy Routing & NAT (DNAT/SNAT) aka Multi WANs on CentOS 5

Originally posted at Unix and Linux but nobody was able to answer it, so m migrating the question here: My question is regarding Source Based Policy Routing on CentOS 5 with 2 WANs plus a LAN (NAT) ...
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1answer
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how to open ports for localhost on linux?

I've been reading for the past hour about opening ports on Ubuntu 12.04 and I can't seem to get anything to work. I'm running a program with an RPC server accepting local connections on localhost (127....
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How to redirect a port using IPTables in Red Hat Linux (RHEL)?

I'd like to forward port 80 to 8080. So I tried to edit /etc/syscongfig/iptables: -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8080 But got: # service iptables restart ...
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1answer
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IPTables - unknown error 4294967295

I've moved an old Slackware 11 installation from a physical PC to a virtualized in ESXi. Everything seems to work fine except for one rule in iptables, namely the row: iptables -t filter -I INPUT -m ...
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1answer
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How to route specific traffic through OpenVPN?

I'm running a server at home with rtorrent and apache2. I would like to route my rtorrent traffic via OpenVPN and since im kinda new to OpenVPN and iptables i would like to have a user friendly guide. ...
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1answer
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Port forwarding with IPTABLES and VBox

I have a small problem with getting a proper configuration of iptables under Ubuntu. But before, let me describe the network configuration: I am using xDSL line terminated with modem+router+DHCP ...
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1answer
623 views

Save iptables when iptables-save doesn't exist?

I'm working on a Soekris net4801 that is running an unknown distro of Linux. The kernel is 2.4.29, and iptables is v1.3.4. I can't work out how to save the iptables. I searched the whole system for ...
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How to install firewall script in Ubuntu?

https://help.ubuntu.com/community/Router/Firewall In the link above there is a firewall script described. How can I install this script in Ubuntu 10.0.4 desktop?
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How do I kill existing network connections on Linux?

I've been working on a project that is nearly complete: to be able to kill my children's internet connections at the touch of a button. I've implemented part of the solution by basically calling: ...
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2answers
154 views

Forward HTTP access to another IP address in iptables

Hi I am using my local internet provider whenever I visit any page and when I look at a source code of the page there is a script injected into code http://10.80.196.101:8080/www/default/base....
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1answer
129 views

No connection between devices in local network

I have home server that also works as router (gateway). It has 2 interfaces one for internet (enp4s0) and another (enp4s1) looks into local network. All devices from local network uses internet from ...
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61 views

Iptable & routing in a virtualbox lab

I set up a virtual box lab, with the following configuration: Vitual Lab Setup In order to make the lab working i create with a script the following interfaces, enabling port forwarding for the ...
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782 views

Routing subnet to specific routing table with fwmark, direct to ISP and VPN

Introduction I'm trying to set up a VPN on my router so that I have two routing tables. I want it so that all the filtering is done with iptables, and iproute just acts on the specific fwmarks, ie ...