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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rsyslog loses messages from firewall

I am trying to make rsyslog to log messages from iptables MASQUERADE. I have iptables LOG rule in nat table and PREROUTING chain before the MASQUERADE rules. The actual iptables rules: iptables -t ...
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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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Port based NAT-ing with iptables

On eth0 port we have public IP, and eth1 we have IP 10.31.0.1 which provides DHCP and Squid service. Ports 8080,53,67,80,443 are open. Now for an application we have to open 1521,8443 ports so that ...
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MaraDNS- Unable to forward DNS queries

I tried forwarding DNS queries to Google DNS but it is not working. Below is the content of my /etc/mararc file: csv2 = {} csv2["example.net."] = "db.example.net" csv2["google.com."] = ...
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12 views

Cannot access DNS from external network

I have setup a MaraDNS instance on CentOS 6.5. I can access the DNS records from local machine—on which MaraDNS is installed—by doing nslookup but cannot access the DNS server records from Internet on ...
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16 views

Configuring iptables for guest WLAN in DD-WRT

I'm constantly failing to get a guest WLAN in DD-WRT working. I can connect to the second SSID and get an IP address of the second DHCP server range. But I cannot connect to the internet. I followed ...
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iptables syntax to forward remote desktop requests to a virtual machine on CentOS host

I can rdesktop into a VM running Windows XP hosted on my CentOS 5.4 machine from the hosting machine and work just fine using the private address (192.168.122.65), but I now need to allow remote ...
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9 views

Using ppp0 via VPN for everything but ftp

I have an ubuntu server I use to wget certain files from the internet via a VPN. I have set the VPN up using PPP0 and currently adjust the route like this: sudo route add default ppp0 Everything ...
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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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48 views

How can I route all client Internet traffic through an OpenVPN TAP bridge with Tomato?

I've inherited a Linksys WRT54G router and I'm looking to use either Tomato or DD-WRT to set it up as an OpenVPN client to my home network in Chicago, forwarding all traffic through the VPN link so I ...
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15 views

Route Specific URL to another interface on Linux

I have a Raspberry Pi Model B running Raspian. RPi is in between of my local network and Internet Router (as gateway; so all traffic is passing from RPi's eth0 interface to virtual interface eth1). I ...
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4k views

DD-WRT firewall rule configuration

I'm using DD-WRT on my linksys router. I want to limit each user on my network to 200 connections at any given time. Does anyone know the rules I enter the firewall in DD-WRT admit panel. I tried ...
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11 views

Determining whether a port is closed (no one is listening) or iptables reject my host

Can I tell whether the service I'm calling has a reject rule in its iptables or it doesn't listen on the port I'm calling? it seems that I always get icmp port unreachable
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12 views

iptables - Cannot redirect with 443 (Https) port

I'm using this command to redirect all web traffic (http and https) to my local server iptables -t nat -I PREROUTING -p tcp --match multiport --dports 80,443 -j DNAT --to 192.168.11.100 But when i ...
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iptables failed with “ iptables v1.4.21: Couldn't load match `-d':No such file or directory” message

I am running kernel 3.14.18 and using iptables 1.4.21, built with these options --static-enable --disable-shared. When I run this command: /sbin/iptables -A PREROUTING -m -d 127.3.0.2/24 -j DNAT ...
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How to use iptables to connect proxy server

In my company, all http and https must connect to a proxy server, which means we must set proxy in our web browser. Our department has an internal network (192.168.0.xxx). I use a Linux server as ...
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iptables - How to remove connection tracking

I'm using this command for redirect all web traffic (http) into my local web server iptables -t nat -I PREROUTING -p tcp --dport 80 -j DNAT --to 192.168.11.100 Then i test, access a website and got ...
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Log and drop packets with iptables

I am using these two alternatives to log packages dropped with iptables: -A INPUT -p tcp --dport 21 -j LOGNDROP # We do not have FTP # The LOGNDROP chain: log messages (rate-limited) and drop all ...
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1answer
55 views

SSH reverse tunnel into Docker container

I need to xdebug something that fails on the server in a docker container and from my laptop I have ran ssh -R 9000:localhost:9000 server and verified the tunnel by telnet localhost 9000. So far so ...
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2answers
10 views

How configure requests from other ports to port 443?

I am trying to configure my first https, and i think i get it, but there is a problem: the site wont open in http, just https, because of this, i want redirect everything to https. I am using ...
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Forward 3389 port from Ubuntu to a Windows Server

I have an Ubuntu 14 Server Live, I need to get access to an internal Windows server through Ubuntu, I have tried Apache2 Reverse Proxy and tried iptables, but it’s not working as expected. And I ...
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33 views

How to allow only subnet for port with iptables

What i am trying to do is to DROP any packets to specific UDP port, except those one from my secured subnet 10.8.0.0/24. iptables -t nat -A --src 10.8.0.0/24 -p udp --destination-port 63210 -j ACCEPT ...
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How can I see the currently installed netfilter hooks?

Not just the iptables, is it possible to see the currently installed netfilter hooks in Linux PC? Such as the home-made kernel modules that installs netfilter hooks for someone's own filtering rule?
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37 views

Open ports with iptables — still closed

I'm trying to open some ports for a gameserver, which is running on my Linux vServer (Ubuntu 14.04 LTS 64bit). The game needs the following ports: 16261 (UDP) 16262 (TCP) // Player 1 16263 (TCP) // ...
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21 views

Connectivity from different network segment

I have 3 machines 10.10.3.1 Windows # srv1 10.10.3.2 Lubuntu # srv2 10.10.200.1 Windows #cli1 network masks are 255.255.255.240 I can succesfully ping from cli1 to srv1 srv1 to srv2 srv2 to ...
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35 views

Connecting to mysql server at 127.0.0.1:3307 with iptables port redirect

I have a ruby application which, for various reasons, connects to a mysql server running at 127.0.0.1:3307. This works perfectly on the server side, but now I want to run this application on my ...
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11 views

IPTables NAT to webserver how to forward real remote IP

I have a simple setup where I host a webserver in my local LAN 172.16.0.0/27, port 80. It is connected to my DD-WRT router that has a publich IP (direct Internet connection), let's say 1.2.3.4. I set ...
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54 views

How to use iptables to allow traffic only throug ONE SPECIFIC VPN

I'm trying to allow all traffic from my Banana PI running Lubuntu to only go to my LAN or otherwise through an VPN Server. I'm following this guide: ...
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35 views

How to redirect TCP traffic from one virtual machine to another in Linux?

What is the simplest way to redirect all TCP traffic from one virtual machine to another in Ubuntu Linux and reverse? And what type of connection I suppose to use in VirtualBox?
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44 views

Using iptables to allow LAN and drop WAN of unknown devices

I posted this over on stackoverflow but it was off-topic. I have looked around and couldn't find the answer to my question. I am using a raspberry pi as an internet gateway between my LAN and two ...
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Iptables Port Forwarding To Different IPs Based on Port [duplicate]

On a CentOS 6 server with an IP address of 172.16.1.10, how can I configure iptables to route traffic destined for 172.16.1.10:80 to 192.168.1.10:80, and traffic destined for 172.16.1.10:8080 to ...
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62 views

IPTABLES NAT port forwarding

I'm trying to setup a Linux box to act as a very simple 2 NIC router. I've read over the instructions on the bot Archlinux and Gentoo wikis and gotten the same result, masquerading works but not port ...
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42 views

DD-WRT Wifidog - Redirect isn't working

I have flashed a ASUS AC-RT56U router with DD-WRT version V24-preSP 2201412-22-2014-r25697. Now I want to make it into a hotspot with wifidog TO PLACE IN A SMALL BUSINESS (FITNESS CENTRE) I have ...
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2answers
163 views

Port Forward inside Router (DD-WRT)

I have configured an SSH tunnel on my DD-WRT router using the default port 22. I would like to open another port on my router as a proxy port for SSH, say port 80, in case a firewall prevents me from ...
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51 views

How to split traffic between vpn and ISP

I have vps with configured open VPN server and my router with openWRT and openVPN client. In this moment I can route all my traffic via vpn or ISP. But I want route some connections (for example on ...
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43 views

Routing 6to4 packets through NAT

I have a linux router(dd-wrt w/o ipv6 module, no space for that) and a linux PC(Arch linux). I'm trying to setup my router to forward 6to4 packets(protocol 41) to my PC and setup the tunnel on it. ...
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25 views

iptables drop packets by IP protocol type

Is it possible to have iptables rules to drop packets by IP protocol type as described in [http://www.tutorialspoint.com/ipv4/ipv4_packet_structure.htm]? (ICMP is 1, TCP is 6 and UDP is 17, but what ...
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34 views

Redirect traffic destined for IP and port

I have a program that wants to connect to 1.2.3.4 on port 5678, but it can't because the port is blocked on our network. However, I do have an SSH tunnel set up that redirects localhost:5678 to ...
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How to configure iptables to set public IP for outgoing traffic from private IP

I have multiple public IPs at home: 1.1.1.1 (main IP) 2.2.2.2 (additional IP) In my local network, I have two computers, let's say 192.168.1.1 (PC1) 192.168.1.2 (PC2) Infront of the computers I ...
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29 views

slow internet access when routing via a server (both using iptables NAT and ssh tunnelling)

I have a spare computer powered by a dual core intel atom N550 CPU and 2GB RAM (I will refer this as "the server"). It is running lubuntu 14.10 x86 (32 bit) with lightdm service disabled (hence, no ...
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1answer
16 views

How do you force linux to treat a tcp packet as if it were at the destination ip?

The situation: A tcp packet arrives on eth0 with destination 8.8.8.8. This packet meets some criteria that makes me want to intercept it (lets say I am interested in all packets from source ...
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40 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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1answer
3k views

How to use NAT iptables rules for hostapd

My PC is equipped with two net interfaces - wlan0 and eth0. I want to use WiFi port as access point on wlan0. So i use hostapd facility and it works properly in routing mode in local network. Users ...
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39 views

DDWRT - OpenVPN connects, but can't communicate

This seems to be a popular topic, but I can't find any solution to the same problem I am having. Here's the setup: I have a DD-WRT router (build 14896) on a linksys WRT54GL. I have one file server ...
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24 views

how to capture “DROP”ped packets on OUTPUT of iptables?

having a fairly complex OUTPUT processing on iptables, how does one go about capturing / displaying (at least similarly to how tcpdump captures them) the packets that were to leave through an ...
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14 views

Webserver connected to VPN: Way of incoming traffic?

All apologies if my question is unclear from the start; but: I have a webserver which is a rented root-server at a provider. It is running a webshop that is openly accessible. It is necessary to ...
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36 views

Iptables stops the network after a while

I have 3 dedicated servers (same hardware Supermicro X8STi and same bios) with CeontOS 7 Linux 64Bit and I'm having a problem with one of them, with iptables to be precise. When I change the policy ...
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1answer
1k views

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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29 views

Iptables rules suddenly not working

I'm trying to set up a webserver using an Odroid U3; as OS I have Debian 7.4. The issue came when trying to load the iptables rules with iptables-persistent. I'm using the same file with rules I've ...
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58 views

Block archive.today From Crawling My Site?

My website is being scraped by archive.today. This site is similar to the reputable archive.org, but archive.today does not obey robots.txt, spoofs a generic user-agent and tried to hide its IPs. The ...