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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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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154 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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235 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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138 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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1answer
85 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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79 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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71 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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60 views

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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132 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
37 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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388 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
4k 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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177 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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103 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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19 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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49 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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1answer
77 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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112 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 ...
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100 views

Routing traffic around VPN

I recently setup a OpenVPN client on my HTPC, however once I connected to the VPN server I was no longer able to remotely SSH or connect to the other servers I had running on the HTPC. I followed ...
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1answer
885 views

configure iptables to block all(as much as possible) bittorrent traffic

good day all This is my current iptables setup Generated by iptables-save v1.4.7 on Wed Apr 9 13:50:31 2014 *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0] :LOGDROP - ...
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59 views

iptables always needs restart

I have a CentOS 7 PC, on which I'm using iptables. I have an Oracle 11gR2 instance on that PC and I need to access is from other PCs in the LAN. My /etc/sysconfig/iptables: # Generated by ...
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1answer
845 views

Can ping but can't connect (curl, wget, apt-get, etc.) (rasberry pi server)

Background: I am trying to set up a rasberry pi server. Everything was going well and my pi could apt-get update etc, until I got the port forwarding to work and ssh to work outside of the LAN. I ...
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37 views

blocking port54370 tomato router

I'am having a huge amount of outbound traffic on my network. source port is 54370. Jan 16 00:34:55 unknown user.warn kernel: ACCEPT IN=br0 OUT=vlan1 SRC=192.168.11.88 DST=192.168.0.11 LEN=116 ...
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34 views

How to create two different open VPN link between two hosts?

I want to create OpenVPN tunnel between two Ubuntu 12.10 hosts which has two interfaces, say: Host1: eth0, eth1 Host2: eth0, eth1 A tunnel is wanted between: Host1 (eth0) <-> Host 2 (eth0) Host1 ...
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21 views

how to Connection from a remote system to another via multiple squid proxies?

I have a setup that sending data from host 1 to host 2 via proxy running different middle hosts. I don't want just routing packets in middlehost and send to destination. The reason is I run new MPTCP ...
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370 views

Is this firewall completely secure?

I'd like to know if there's any holes/flaws in this firewall setup. I want to lock down the server as much as possible so it is impossible to hack in to. The only services running are openvpn and ssh. ...
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153 views

Access lxc container services from other lxc containers via host

I've got a laptop with Ubuntu 14 Desktop. The laptop has WLAN connection to my LAN and is managed by network manager. Of cause, the laptop a nic (eth0), too, but it is not connected. I use this laptop ...
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158 views

iptables out bound port to remote mysql

Following is my iptables file on my centos, I am unable to open 3306 port to connect to remote mysql server. I dont know what I am doing wrong although it looks fairly simple. When I stop the iptable ...
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31 views

How do I reroute a DNS request?

I have a Technicolor (Thomson) Modem, and I want to reroute a DNS request coming from a specific IP to another DNS server. I have an iptables command looking like this: iptables -I PREROUTING -t nat ...
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28 views

Iptables rules for host-only interface

I'm in this situation. I have an host machine running Ubuntu and 2 virtual machines using VirtualBox. They're connected via the host-only option on the virtual interface "vboxnet0". What I want to ...
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53 views

Share Internet through Arch Linux VM

I'm working with a LAN which is behind a router that I don't control. The router admin has allowed internet access to one IP address 192.168.0.50. I would like to create an arch linux VM at that ip ...
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39 views

How to acchieve what http_proxy environment variable does for all traffic leaving the system?

I set up a trafficserver (5.1.2) instance as HTTP cache on a machine in my local network and now I'm looking for a way to enforce the usage of the proxy for HTTP requests to the outside world on port ...
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153 views

How do I set Input interface is output interface

I have eth0 with IP X.X.X.X and eth0:0 with IP Y.Y.Y.Y. My goal is if I connect to eth0 then output ip shoud be X.X.X.X and if I connect to eth0:0 the output ip should be Y.Y.Y.Y. Example: VPN ...
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48 views

Iptables newbie pain

I got a host (WINDOW7) and a guest (DEBIAN7.7) virtualized by VirtualBox. I configure an eth1 interface as host-only. My host can ping the guest and vice-versa, host can connect via ssh too. Now I ...
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40 views

IpTables: rule to allowing outgoing traffic

I need rule to allowing outgoing traffic from intranet addresses 192.168.X.X to foreign addresses 123.123.123.0-63 and by using tcp Protocol. Sorry for bad english Thanks
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105 views

Limit connections per second with iptables/ufw

How can I tweak the following entries to allow more requests per second? Maximum hitcount is 20 if you do not edit some other config files. The entry of my /etc/ufw/before.rules file -A ...
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49 views

Remove iptables rules from recovery system?

I have a remote dedicated server and accidentally added some iptables rules that killed network access. I am only able to access SSH in recovery mode, which gives me access to the filesystem. I can't ...
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147 views

Can a Linux machine have two the same IP addresses on different interfaces/networks?

Is it possible to have two the same IP addresses and subnets assigned from two different interfaces/networks? How would such machine behave? How would route table look like?
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114 views

Blocking 127.0.0.1 in iptables?

I'm in the process of setting up some rules for iptables. Not wanting to make any errors I am currently only logging activity. The logs have shown a number of entries for 127.0.0.1 hitting my rules: ...
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216 views

FTP does not work properly when connected to OpenVPN

I am connected to an OpenVPN server and would like to list all files on a FTP server. ftp> ls 500 I won't open a connection to 10.125.1.20 (only to 31.x.x.100) ftp: bind: Address already in use ...
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1answer
64 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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How to print iptable firewall rules?

How does one print or dump the firewall rules being used by iptables in an effort to trouble shoot connection problems? I'm fairly certain its going to include -L or --list, but I'm not sure of other ...
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147 views

iptables - UDP Packets from unknown IP addresses

I'm really new to basic systems administration, and this question is a bit difficult for me to Google. I'm setting up a small raspberry pi server for my own personal use, to teach myself some basic ...
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46 views

What minimum'allows' should be used in iptables rules?

I have a Ubuntu 14.04 server which has two Ethernet ports: eth0 directly connects with a custom camera and eth1 connects via LAN cable to a wireless router. I had been developing a web application ...
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977 views

Openvpn connects and responds to ping but no internet access

I have an openvpn server running on raspian and a tunnelblick client on osx. I can connect to the VPN just fine but I have no intenet access. The server responds to ping just fine and the port is open ...
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108 views

how to save iptables rules permanently?

I want to keep some iptables rules permanence, so I just only add the rules manually: /sbin/iptables -I OUTPUT -p tcp --sport 80 -j QUEUE I am sure that the command works, because I could see it ...
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1k views

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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1answer
685 views

How to forward ports through ssh and nat to another machine

I have a problem when using ssh port forwarding and nat simoultaneously. Situation: Machine A runs a webserver on port 8080 Machine B is a raspberry pi which works like a little router. It has two ...
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34 views

iptables INPUT command

On a ubuntu1, this is iptables command: sudo iptables -A INPUT -p icmp -j DROP so on the other computer (xp1) I can not ping the ubuntu1.So this is OK. But On ubutnu I [[ can ]] ping xp1. and I ...