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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Rerouting traffic from port 80 to another port on a single ip

I have a server with multiple IP addresses associated with it. I'm trying to run a node.js web server (which I do not want to run as root), using only one of those ip addresses (it would be very bad ...
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754 views

DHCP Client Can't Find DHCP Server

I currently have 3 machines: CentOS (router) eth1 - 18.0.168.1 eth2 - 145.165.34.1 Windows Server 2008 (server) 18.0.168.2 DHCP scope - 145.165.34.10 - 145.165.34.20 Windows 7 (client) Supposed ...
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682 views

Linux Iptables Routing

I need help with a problem. My setup is: CentOS (Router) eth1 18.0.168.1 255.255.248.0 eth2 145.165.34.1 255.255.254.0 Windows Server 2008 18.0.168.2 My problem is from the Windows machine, I ...
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What means empty iptables?

I'm using CentOS and when type the command: iptables -L -v The output is as follows: Chain INPUT (policy ACCEPT 19614 packets, 2312K bytes) pkts bytes target prot opt in out ...
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IPv4, IPv6 and IPTables

I have just recently learned that even if I block all traffic to my webserver using iptables it is still vulnerable to external attacks via IPv6. In my understanding, this renders iptables-only ...
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98 views

NATing with a single-homed machine possible?

I have the following setup: a) a single-homed machine, A, that can see the Internet. b) other machines B, C, and D that cannot see the Internet. c) A, B, C, and D can see each other. d) all ...
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iptables ACCEPT policy

In Redhat EL 6, iptables INPUT policy is ACCEPT but INPUT chain has REJECT entry in the end. /etc/syconfig/iptables is as below: *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] ...
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432 views

Firewalling all incoming traffic with custom rules

How do you automatically block all incoming traffic by creating custom rule for every connection (in real time) using iptables? To clarify - the situation is that my linux box is being DDOSed via ...
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206 views

How to read iptables -L output?

I'm rather new to iptables, and I'm trying to understand its output. I tried to RTFM, but to no avail when it comes to little details like these. When iptables -vnL gives me a line such as: Chain ...
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Block all ports except SSH/HTTP in ipchains and iptables

How can I block all ports except ssh (port 22) httpd (port 80) using iptables and iphains?
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960 views

linux drops packet when trying to route it - why?

I track packets using LOG targets for all chains of all tables and the last chain I see my packet in is the POSTROUTING chain of the mangle table: mangle_PREROUTING: IN=eth0 OUT= ...
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203 views

Using my previous desktop computer as custom ubuntu router, will throughput be high?

I'm going to be redoing my home network soon and am thinking of using a dedicated ubuntu machine to use as the router/firewall as well as being a web server, nas (media file server), dns, wifi, and ...
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764 views

Linux, how to force all traffic to specific host over VPN?

I'm trying to ensure that all traffic to our stats server is forced over the VPN, in the case that the VPN falls down, it shouldn't be that the traffic tries to route over the WAN. To short-circuit ...
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2answers
5k views

How to alias an IP address to make DLNA resource accessible from different IP network

what I have I have a home wifi network 192.168.1.0/24 having DLNA resource 192.168.1.100. I have a TV with ethernet and a netbook with both wifi and ethernet interfaces. I want to make my notebook ...
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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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iptables vs route

What's the difference between these two tools? Can anybody tell me what the main workflow of networking behind Linux (in relation to IPv4 packet filtering, NAT and IP routing table) is?
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iptables for transparent TCP proxy

Here's my situation. I have an iPad, a TiVo, and an dd-wrt router on my network, along with a machine that I'd like to use to sniff/decrypt draffic between the iPad and the TiVo. The iPad has an app ...
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771 views

Internet Connection Sharing bypassing MAC Filter in Ubuntu Linux

My university gives me an internet connection by Ethernet, DHCP but they have installed MAC Filtering to allow only using my PC. I have a wireless router TL-WR340GD. which has MAC address cloning ...
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70 views

Regulate outgoing ip traffic on a VM

I am making a virtual network setup for my high school cybersecurity team to practice. I am connecting all the VMs together through a VPN and then people who are practicing will VPN in and ssh/remote ...
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Setup routing and iptables for new VPN connection to redirect **only** ports 80 and 443

I have a new VPN connection (using openvpn) to allow me to route around some ISP restrictions. Whilst it is working fine, it is taking all the traffic over the vpn. This is causing me issues for ...
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117 views

Mark packets across computers?

I use Transmission on Ubuntu and I'm having this issue, which basically says that QoS is broken because there is no way to limit which outgoing ports uses. I was thinking of doing a dirty and ugly ...
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266 views

Push local traffic “outside” the nat

I have a server functioning as my nat that hosts some services. When I locally connect via UDP to this server it my client uses the public ip but the server answers with its local ip. So the question ...
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1answer
631 views

Feedback to router users during access-restricted hours for DD-WRT

Following router schedule rules that I change often, the stock firmware on my D-Link 825NA rev. B redirects HTTP requests to a built-in "Access denied!" warning at appointed times. I just upgraded ...
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573 views

SSH login with secure IP VPN

I have a PC behind a router with port forwarding setup Port 22 for SSH which works perfectly - I can login and everything. What I am trying to do is let this PC connect to a VPN and only allow ...
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734 views

Iptables port redirecting. Rule doesn't work or show up in iptabels

I'm trying to redirect some incoming TCP traffic on port 443 to port 999 with iptables in an Ubuntu VM. I am using sudo iptables -t nat -A PREROUTING -p tcp --destination-port 443 -j REDIRECT ...
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How to deliberately introduce a delay for incoming UDP packets

I want each packet (that match iptables rule) to be delayed by some fixed time interval. How to to this? Preudocode: iptables -A INPUT -p udp <more conditions> -j DELAY --delay 50000 # delay ...
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447 views

filtering Internet traffic and caching on another machine using a dd-wrt router

In my home network, I have a spare machine which I would like to configure to filter Internet traffic (block ads) as well as cache content. I would like to tell my DD-WRT router to pass all Internet ...
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98 views

Portforwarding to VM doesnt work.. anymore

I have a windows 2k8 server vm on my Ubuntuserver which I use for i.e terraria & apache. It was working great before a little minor accident when the electricity stopped flowing through the cables ...
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3answers
84 views

Chaining subnet fails

Is it possible to do the following: Machine1 Kubuntu 8.04 desktop wired internet Cable modem Machine2 eepc701 Xubuntu 1O.04 wired machine1 cross ethernet cable Machine3 nokia n900 wireless to ...
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190 views

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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432 views

Open a linux port without using iptables in Centos? [closed]

just a quick question, is it possible to open a port on linux Centos without using iptables? If so, how do I do that from the command line?
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IPtables: Blocking all traffic on an interface except select ports

I have four interfaces on my system (eth0, eth1, eth2, and eth3). I want to block all incoming and outgoing traffic on eth2 except for port 80 and 443, although I'm only worrying about 80 right now. ...
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How can I restrict my Virtual Machine using an iptables rule?

I am using CentOS Linux and am planning to setup a rule on my VM's iptable. I want to restrict all outgoing and incoming packets to the VM for a temporary period and allow only the DHCP packet to ...
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How to drop traffic before it hits existing iptables conntrack rule?

I am running an application that injects iptables connection tracking rules into the kernel so the machine can forward incoming UDP traffic to its destination as fast as possible. Some of the ...
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320 views

In Linux can I direct all traffic from a specific ip address or mac address to file

In Linux can I direct all traffic from a specific ip address or mac address to file. I am look of a way to take all traffic from a specific ip address or mac address and put it into a file. Does ...
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387 views

How can a PPTD VPN route traffic to other servers on network?

I a have a number of servers which expose various public services to the web. These are behind a server which is acting as a firewall using IPTables and forwards traffic to and from the servers. All ...
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Ubuntu 11.10 firewall/gateway - no client internet access

I have read many other posts but cannot figure this out. eth0 is my external connected to a Comcast modem. The server has internet access with no issues. eth1 is internal and running DHCP for the ...
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919 views

Using iptables to selectively route outgoing requests?

I'd like to set up my Dd-WRT firewall so that it uses the VPN service from a VPN provider to access a bunch of destinations and normal route foe all other requests. In detail: giganews.com would be ...
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210 views

conectivity problem

I have 2 PCs (anuin and hed), both running Linux that are connected via ethernet (192.168.1.1 and 192.168.1.3). Both PCs can ping each other. anuin is connected to the internet via an USB-stick ...
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323 views

iptables Settings as WAN Input for Router

I have an eee running ArchLinux with wireless access to the Internet. I want to use it as the WAN input for an Asus RT-G32 router into which it is hardwired. The router in turn is hooked up to a ...
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will the left|rightfirewall option of StrongSwan open UDP 500/4500 and protocol number 50 on iptable?

I know the StrongSwan use UDP 500 and 4500 for IKE traffic and IP protocal number 50 for ESP packages. I am not sure the usage of left|rightfirewall ...
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Remove port aliases in iptables

How can I make iptables show me port numbers instead of aliases for well known port numbers (eg. http for 80, https for 443 etc.). Is there a way to make it show just port numbers at all times?
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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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1answer
398 views

Why small TCP connections succeeds, but big ones fails?

Sometimes from Linux system I see the following weird behaviour: I able to ping things and sometimes use some services, but networking is very bad. For example, now I routed connection through my ...
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2k views

Routing from the DMZ to the interior network only

I have a home network connected to Verizon's FIOS service. Verizon's ActionTec router is connected to the ONT via coax to establish the MOCA network. My DD-WRT router's WAN port is connected to one ...
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How do I block all ports except 22 and 80 in Fedora's iptables? [duplicate]

I am trying to only allow port 22 TCP/UDP and port 80 TCP/UDP from anywhere using Fedora 15 iptables, and all the rest will be never accessible nor scannable from a public network. But it never ...
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274 views

Blocking a botting URL to an Linux server running Apache

I have a webserver running OpenSUSE 11.1 and I need to block a URL. The reason I want to block a URL is because it seems to have a different IP address all the time, but the URL stays the same. I'd ...
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I need a traffic monitor for Linux, that only counts in a specific wireless network

I need a simple traffic monitor for Linux, that counts the traffic in a specific wireless network because I have volume restrictions on that one. I tried it using the following iptables rule: ...
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709 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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Rackspace Firewall/Gateway Setup

I have rackspace account and wish to have this sort of setup: Firewall/Gateway eth0 - Public IP (56.X.X.X) eth1 - Private IP (10.X.X.X) Ubuntu 10.10. Accepts connections from the internet and ...