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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Redirect PROXY traffic to test box using IPTABLES

Marked this as answered. I'm going to pass on trying to get this to work. It was only for testing. I'm currently using a proxy server (squid) that's listening on port 8080. Users' browsers are ...
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iptables as a proxy

I'm not sure how to start better so i'll be straight. I have to travel to a foreign country, but i need access to a server that is local to my hometown network. I have a DD-WRT router with only my PC ...
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Using iptables to give an LXC container a routable IP

I'm using Docker to manage LXC containers. At the moment Docker configures the underlying LXC container with host-only routing and then uses iptables/DNAT to punch holes into the container, making it ...
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201 views

Linux Traffic Control of internet downlink with router as a client

I'd like to shape my internet downlink bandwidth in a bit peculiar way. My linux box at home acts as a router and a torrent client (and other downloads), making my router a router and client inside my ...
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Forwarding RDP connections with iptables

I have a workstation that runs Windows 7 as the host, and Ubuntu Server 12.04 in VMware on a bridged network. Both have their own static public IP address. However, I only have one hostname to work ...
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386 views

Iptables output with options unknown

I have been learning and studying up on iptables and port forwarding. There is a sample iptables output I can't decipher. It has the options --dir, --pol, and -m. Although I am familiar with -m it ...
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Fedora's firewalld vs iptables

I am on Fedora 19. Is my understanding correct that as long as firewalld is up and running (and properly configured using firewall-config) the contents of the /etc/sysconfig/iptables has no meaning? ...
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Cannot open port 8080

I'm running a VmWare with an application under JBoss starting up on port 8080. I'm able to access the app from outside the VM if the iptables are off. However, I must turn on iptables due to some ...
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113 views

IPTABLES to block sites on browser

I am trying to block a specific IP address from being accessed using the browser on my system. I added a simple rule as below iptables -A OUTPUT -d <IP> -j DROP The site gets blocked in the ...
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373 views

iptables not working on DDWRT firewall

I have write a firewall rules for DDWRT router but I didn't work. What I needed is, I would like to set all my wireless user, once it reach daily quota which is 200mb it will disconnected from the ...
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3k views

Can't connect to mysql by telnet 127.0.0.1

I can't telnet MySQL on my localhost. MySQL is up and running and works fine with Apache-SSL/PHP/MySQL server but I can't connect by telnet: telnet 127.0.0.1 3306 Trying 127.0.0.1... telnet: Unable ...
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36 views

Modify rule when service crashes

I have a iptables rule in PREROUTING that redirects all incoming to a specific port, where a service consumes the data. Is there a dynamic way to determine if the service has crashed and remove the ...
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1k views

Forward to Internal IP and Port From a Single IP Address on DDWRT Router

I'm trying to follow this guide and I have a simple request that I haven't been able to solve. I'd like to only accept requests from a specific IP address to a host within my internal network at home. ...
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384 views

DDWRT Port Forwarding Request from Dynamic IP

I'm running a DDWRT router with a NAS behind it. The NAS runs a service called Cloud Station. I'd like to restrict access to Cloud Station to a handful of hosts (family members). Each family member ...
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Blocking all sites/IP address but Google.se with iptables

Im trying to block all IPs but Google.se. It doesnt work (Site does not display) Here is what I wrote: #/bin/sh echo "Flushing IPTables..." sleep 1 iptables -F iptables -X iptables -t nat -F ...
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661 views

Manually Editing iptables

I'm using CentOS. What I'm wondering is, what happens if I manually edit /etc/sysconfig/iptables and save it? Is that the definitive source? When I type iptables -L I get something that doesn't match ...
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193 views

How to drop IP packets received on the default route interface when no other than default route is found?

I am setting up a router based on a linux kernel. As expected, ipv4 packets received on the interface used by default route are sent back to the same interface in case no other route is found. Is ...
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2k views

Iptables drop forward packets to specific host

I am having trouble isolating a specific host from others on my lan. What I am trying to do is only allow communication between 192.168.0.2. and 192.168.0.8 as well as not allow any other host to ...
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134 views

Can iptables be used to convert a single-homed host into a NAT server?

I have an Internet-enabled machine, HostA, with one NIC. I have another machine, HostB, with one NIC that is not Internet-enabled. I would like HostB to be able to share HostA's Internet-connection. ...
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111 views

Linux gateway / DNAT: restrict to certain interfaces

I have various machines with a number of network interfaces: eth0: a local LAN eth1: sometimes used for the connection to the Internet gateway ppp0: Modem uplink as an alternative to eth1 tun0: ...
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35 views

Problems in creating rules in iptable

Hello to all :) I need a little help with creating a rules. Im starting to learn iptables and firewalls but I have some questions. I need to allow HTTP communication only from PcA to PcB./ My code is: ...
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938 views

How does iptables masquerading allow to access a different local subnet?

My Linksys router (IP 192.168.1.1 inside a /24 subnet) is connected to my ADSL modem (IP 10.0.0.138 inside a /24 subnet) to establish an internet connection via PPPoE. To be able to access the modem's ...
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686 views

How to allow access to only specific IPs with Parallels VZ built-in firewall?

How can I use Parallels Virtuozzo's built-in firewall utility (called psa-firewall under the hood apparently actually psa-firewall seems to be a seperate Plesk interface - either way, it's basically a ...
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343 views

Iptables: Allow Internal LAN to access INTERNET

I have an internal network behind my router on eth0, and I have my router connected to the internet thorugh wlan0. I can't access the internet from inside the lan, how can I fix this? wlan0: ...
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UDP packet and firewall

I notice when I send udp packets from computer A to computer B, B can receive the upd packets correctly but if I send udp packets from computer B to computer A the udp packets are not received A and ...
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189 views

IPTables masquerading stops working

In a classical SOHO setup I am running a Debian box as router/firewall. For an unknown time now I have an issue, where the MASQUERADING on the output connection (PPPoE) stops working for one of the ...
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424 views

Iptables: allow specific ips on specific port

I am trying to allow a few IPs on port 80 and disallow all other from access port 80. Can someone suggest the iptables rules needed for this to occur?
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DNS resolving broken after installation of bind due to iptables

I successfully configured my web server (Apache, PHP etc.) and blocked the ports I don't need using iptables, which was working perfectly fine. Today, I installed BIND and configured it, which also ...
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556 views

Port 6667 can't be reached outside of localhost

I've got IRCD-Hybrid installed with the following listen config: /* listen {}: contain information about the ports ircd listens on (OLD P:) */ listen { /* port: the specific port to listen ...
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677 views

how to telnet redirect ip and host using iptables

I try to telnet from PC 3 To PC 1 and it's redirect to PC 2 PC 1 : 192.168.0.1 PC 2 : 192.168.0.2 PC 3 : 192.168.0.3 i have command like this in PC 1: iptables -t nat -A PREROUTING -p tcp -d ...
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184 views

1:1 NAT IP address using iptables

Suppose I have 2 internal networks: 1.1.1.0/24 and 1.1.2.0/24 I would like to NAT a specific IP address from one network to the other, in which the new address would be obtained via DHCP. For ...
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280 views

CSF Unresolved issue

I began receiving service failures for CSF/LFD once the limit was reached in iptables preventing the service from working properly. I flushed all iptables rules, and redid by rules using CIDR rather ...
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124 views

iptables rule cannot be added

Is there anything wrong with these rules? They cannot be added to iptables, no error but they just don't show up in iptables -vnL iptables -I FORWARD 1 -s 1.2.3.4 -p udp -m connlimit ...
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964 views

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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505 views

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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932 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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430 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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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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73 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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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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490 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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903 views

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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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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803 views

iptables + vpnc + Cisco IP Phone 7941

I have a Linux gateway with kernel 2.6.39 connected to a Cisco ASA 5500 with vpnc. I'm using iptables with masquerading and forwarding to give the LAN access to the tun0 device connected to the VPN. ...
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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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iptables openvpn forward selectively from eth to tun

Simple for those who know, indecipherable for those who don't... I'm running openVPN on (hypothetical) 66.66.66.66, I want to FORWARD incoming traffic, arriving on interface eth0 to interface tun0. ...
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597 views

Removing/Disabling Firewall on Linux CentOs seem to happen temporarily

I tried following the instructions in this link to disable and remove iptables firewall using commands: # service iptables save # service iptables stop # chkconfig iptables off # iptables -F # ...
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453 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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407 views

Linux box acting as wireless access point to share the internet connection

A linux machine is connected to internet over two interfaces ppp0 and ppp1 using two modems. Also this machine acts as wireless access point through an interface say, eth0 with ip address 192.168.1.1 ...
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633 views

Quotas with iptables

pkts bytes target prot opt in out source destination 12770 2385K ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 quota: 2000000 bytes 0 ...