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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Gateway on a virtual network interface used by LXC guests

I'm currently having some problems with configuring a gateway for a virtual network interface. Here is what I've done : I created a virtual network interface : # brctl addbr lxc0 # brctl setfd lxc0 ...
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Iptables - having trouble opening port 443

I am attempting to set up https, but I am having difficulty opening that port. Nmap scan report for localhost (127.0.0.1) Host is up (0.000073s latency). PORT STATE SERVICE 443/tcp closed https ...
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pfctl port forwarding in Mac osx?

-A PREROUTING -s 10.0.10.0/24 -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 8080 -A PREROUTING -s 10.0.10.0/24 -p tcp -m tcp --dport 443 -j REDIRECT --to-ports 8080 -A POSTROUTING -s 10.0.10.0/24 -o ...
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Router 2wire, Slackware desktop in DMZ mode, iptables policy aginst ping, but still pingable

I'm in DMZ mode, so I'm firewalling myself, stealthy all ok, but I get faulty test results from Shields Up that there are pings. Yesterday I couldn't make a connection to game servers work, because ...
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How to enable iptables with verbose mode in DD-WRT?

I want to log all packets to messages through iptables. Can you help me how to set verbose mode in DD-WRT. Just DYI, I have optware installed to store the large messages file and do log rotation.
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411 views

What other ports should I block to maximize server security? PS using IPTABLES

I have blocked ports 80, 9001, 9080. What other ports should be blocked to maximize security? PS: It is a asterisk server / PBX Sorry: New Systems Admin here :) Thanks!
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45 views

Networking - In what scenarios do “RELATED” connections occur?

I am trying to use iptables and ip6tables to establish basic networking security on my webserver. However, I am having a hard time understanding the RELATED state of the conntrack module... I know ...
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blocking port 80 via iptables

I'm having problems with iptables. I am trying to block port 80 from the outside, basically plan is we just need to Tunnel via SSH then we can get on the GUI etc. on a server I have this in my rule: ...
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102 views

Use port forwarding with masquerade

I'm using a debian as a router with nat configured. How can I set up port forwarding, to set an rdp server on the local network for example?
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Linux route/IPtables with internal VM network

I am having some trouble figuring this all out. I have Windows 7 [10.10.30.1] ROUTER [eth0=192.168.4.134 eth1=10.10.30.254] Ubuntu [192.168.4.143] I can ping eth0 and eth1 from Win7, and also ...
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Filezilla not showing directory listing?

I had downloaded iptables from server to my windows desktop .I edited some lines for opening port (2195) .after download i added some line for enabling port using this link ...
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Is this a decent set of IPTables rules?

Can anyone please point out to me whether, assuming that the needs for a given (Ubuntu 12.04) server are only SSH, NTP (client), HTTP(S) and system updates (apt-get or aptitude), the following set of ...
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A dumb about iptable

I saw a iptable command like this: iptables -t nat -A xx -p tcp -m tcp --dport 80 -j DNAT --to %myweb%:80 what's "%" there for? Thanks. Where I can get a manual to tell me what kind of symbols I ...
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iptables firewall only allows internet traffic if source port of 80 is allowed

I am configuring an iptables firewall, currently just to allow http and https traffic. It is working but under a particularly strange rule - I must allow incoming connections with a source port of ...
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430 views

Ubuntu iptables web browsing

I am trying to build iptables to protect my system. After I save my iptables, I cannot connect to any web page (through browser or wget). Is it perhaps related to DNS? I tried to access ...
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iptables - Allowing Established Sessions?

I'm learning how to use iptables on ubuntu server. Can you please explain to me what "Allowing Established Sessions" means and why should I include it in rules? sudo iptables -A INPUT -m conntrack ...
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iptables: Allow only HTTP access for web browsing

Have a linux box, want it locked down but just be able to surf internet on it. Why is this script blocking http too? #!/bin/sh # # iptables -F # #Set default policies for INPUT, FORWARD and OUTPUT ...
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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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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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888 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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788 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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iptables - How to forward all external ports to one local port

I want a service to be running on every external port on my system. Since it wouldn't work to start 65535 single instances of that service (I guess...) I thought of using iptables for this. The ...
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What does an empty iptables mean?

I’m using CentOS and when type in the following iptables command: iptables -L -v The output is as follows: Chain INPUT (policy ACCEPT 19614 packets, 2312K bytes) pkts bytes target prot opt in ...
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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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99 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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213 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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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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Implementing a global proxy with iptables

I'm running a Linux box (Lubuntu 12.04) in an Windows environment where a pac file is used to configure internet access. proxy.pac file: function FindProxyForURL(url, host){ var proxy_yes = "PROXY ...
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Deny all incoming connections with iptables?

I want to make some simple iptables rules to deny all incoming connections and allow outgoing. How can I do that?
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417 views

How to setup IPtables to allow capture network traffic from a virtualbox VM configured with NAT

I would like to have a VirtualBox virtual machine that can't get online. I want to be able to monitor all network traffic attempts from the Linux host. So, if the virtual machine attempts to make a ...
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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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207 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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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 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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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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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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122 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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302 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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Allow access from outside network with dmz and iptables

I'm having a problem with my home network. So my setup is like this: In my Router (using Ubuntu desktop v11.04), I installed squid proxy as my transparent proxy. So I would like to use dyndns ...
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826 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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How to negate a range in iptables?

I've seen people use the exclamation mark (!) in multiple examples, but when I try to use it I get an error. The rule I'm trying: -A OUTPUT -m owner --gid-owner 1006 -d ! 192.168.1.0/24 -j DROP The ...
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iptables trouble: nat with ip alias (virtual interface) not working

I'm setting up an Ubuntu 11.10 server to act as firewall for a network running several different SSL websites. The idea is fairly common: have all public IP's for each site aliased to the public ...
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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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635 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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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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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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1answer
192 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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2answers
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How to blacklist IPs on Windows 7?

I'm trying to find something similar to iptables in Linux for Windows. I've tried using Windows firewall as well as editing the host file to block specific IPs, but had no success. I've also tried ...
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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. ...