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 port based routing

I've been Googling this for days with no success. I connect to a VPN from my server from time to time and I'm trying to configure my Debian server to only use port 80 and 443 through the VPN and all ...
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iptables block everything except http

I'm trying to configure my iptables to block any network traffic except HTTP: iptables -P INPUT DROP #set policy of INPUT to DROP iptables -P OUTPUT DROP #set policy of OUTPUT to DROP iptables -A ...
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Pinging an external server through OpenVPN tunnel doesn’t work

I have an OpenVPN server and a client, and I want to use this tunnel to access not only 10.0.8.0/24 but the whole internet. So far, pinging the server from the client through the tun0 interface works, ...
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Packets marked by iptables only sent to the correct routing table sometimes

I am trying to route packets generated by a specific user out over a VPN. I have this configuration: $ sudo iptables -S -t nat -P PREROUTING ACCEPT -P OUTPUT ACCEPT -P POSTROUTING ACCEPT -A ...
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366 views

Rate limiting traffic between specific hosts (based on their MAC) using iptables

I have setup a simple isolated network consist of following Linux based machines (simplified example): Node1<---->Router<---->Node2 Router's eth0 is connected with Node1's eth0. Router's eth1 is ...
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517 views

Reasons why ports below 1024 cannot be opened

I'm root on a machine I don't know how it was configured. I try to open SSHD on another port than 22 but it does not work. I changed the /etc/ssh/sshd_config file and added a new Port line extra to ...
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752 views

Difference default setting on iptables between CentOS 6.3 and Ubuntu 12.04

I would like to ask in ubuntu 12.04, there is no firewall settings by default? iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD ...
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358 views

internet connection gone after $ iptables -F INPUT

I have a PC with two Ethernet cards, and I was trying to configure my eth1, but when I typed $ iptables -F INPUT, the internet was gone on eth0. Does anyone has any idea how to get my internet ...
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129 views

Separating two networks

I have two routers, R1 and R2. R1 (a stock linksys router running dd-wrt) is connected to internet and is serving internet to a network of 5 devices/PCs running a DHCP server, with a network of ...
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760 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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Firestarter device not ready when booting Ubuntu

I am trying to get firestarter running on Ubuntu 11.10 and I am getting an error: Failed to start Firewall The device eth1 is not ready. Please check your network device settings and make sure ...
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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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344 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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391 views

iptables rules revert on Ubuntu

I'm using iptables on Ubuntu 10.04 and whenever I set iptables rules they will revert after a while. I set them with iptables -I INPUT or iptables -D INPUT and they work immediately and I see them in ...
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356 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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997 views

loopback error, home network

I've setup my router to forward port 80 through to my computer, so I can access it from a dyndns.org domain. The domain and the ip both seem to be totally working, externally (can access it from ...
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1answer
2k views

DD-WRT OpenVPN client - cannot get “lan” connected device to route traffic

I have OpenVPN client setup on DD-WRT openvpn small. client connects and can use traceroute to verify everything is tunneling out the openvpn connection. ip_forward is 1. iptables -t nat -A ...
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156 views

How to setting up iptables for traffic fowarding on port 80 from specific sources

Im running a web server on port80, but i want traffic coming from ip 212.333.111.222 on port 80 to be fowarded to port 9020 on the same server that my web server is rinning at that is my sshd port
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258 views

One website not connecting over shared connection

A website is not opening on a computer that's connected via shared connection (not exactly "shared"). Pinging the website gets Packet filtered message. The setup of my home network is done by Ubuntu ...
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How to white list some ip and all the rest block while having already a DMZ?

I have a Linux machine running which has local ip: 192.168.1.2 connected to a router with public IP 8.8.8.8, now the router 8.8.8.8 has DMZ to 192.168.1.2 As a result spammers, hackers, crackers ...
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Why do my nat iptables rules not work with marked packets?

System: debian squeeze, Linux server 2.6.32-5-amd64 #1 SMP Tue May 13 16:34:35 UTC 2014 x86_64 GNU/Linux, iptables v1.4.8 lsmod | grep iptable iptable_security 2176 0 iptable_mangle ...
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Use Ubuntu Iptable to route public ip to pc in private network

I am currently set up a Ubuntu server as a Router which has two network interface. eth0 -> Connecting to public internet ( 10.10.1.78 ) eth0:1 -> 10.10.1.79 eth0:2 -> 10.10.1.83 eth0:3 -> 10.10.1.81 ...
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iptables catches on DENY but not on ACCEPT place prior to it in the chain

I have a weird problem with my iptables firewall: If I set two consecutive identical rules, the first is ACCEPT and the second is DENY, the incoming packet is denied (and logged as such). How is it ...
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iptables problem in Evil Twin

I've been looking into the Evil Twin method and I found this steps: Creating AP airmon-ng start wlan0 airbase-ng -e PrivateWIFI -c 9 -v mon0 at0 Configuration ifconfig at0 up ifconfig at0 ...
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21 views

How to block docker-mapped ports with a firewall from outside the host without messing up docker routing inside the host?

I have a docker container running on a host with some port mapped to a port on the host. docker run -d -p 9009:9009 someserver I want this machine firewalled off from the internet except for 80, ...
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Why doesn't iptables accept IP address as source?

The command sudo iptables -t nat -A PREROUTING -i eth1 -s ! 192.168.178.30 -p tcp --dport 80 -j DNAT --to 192.168.178.30:3128 fails with Bad argument `192.168.178.30' Try `iptables -h' or ...
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tcpdump capturing packets only when interface is specified

I have tried 3 different ways of capturing a stream of packets coming into my server. Two of them work and the third does not. I am trying to determine why it is missed by the third approach: ...
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17 views

Make traffic go one-way by using iptables

I have a network topology: [C1] - [R1] - [R2] - [C2] C1-R1 network is 192.168.100.0/24 R1-R2 network is 10.9.8.0/30 R2-C2 network is 192.168.200.0/24 What I need to do is to make C2 be able to ...
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130 views

Connecting my Xbox 360 to my Raspberry Pi 2 to use an OpenVPN connection

Here is my brief setup: Xbox360 Raspberry PI 2 running ArchLinuxARM (alarm) The raspberry pi's main ethernet port has a cable connecting directly to my main router The xbox has a cross-over cable ...
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DDWRT - Virtual Interface - firewall command - RDP

I have DD-WWRT flashed on my Linksys e2500v3 router. I added virtual interface to create a guest wifi network that would have access to the internet, but not to the private network or router. At ...
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iptables TCP flags

I'm beginner with iptables and networking so please excuse me for such beginner questions. I found on the Internet part of filtering malformed packets: /usr/bin/sudo /sbin/iptables -A tcpchk -p tcp ...
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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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77 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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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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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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286 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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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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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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Iptables: Filtering string encrypted by ssl

I need to filter (send to BANRULES set) incoming http/https packets with a certain string (matchword). I do it easy when ssl is not in use (port 80): iptables -A INPUT -p tcp -m tcp --dport 80 -m ...
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141 views

How to forward http request to a proxy server?

I have an Internet Linux server and my client computer (running windows) accesses internet via a SSH tunnel to the the server. Now for some reason this server can only accesses internet by a http ...
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Nodejs remote debugging ports closed

I have a problem with nodejs remote debugging. I'm using centos on remote server and phpstorm on my PC. When I open putty I type the command: node --debug-brk=5858 main_server.js, and get the ...
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67 views

Debian 7 - iptables 'filter' not supported?

Am attempting to forward/ masquerade connections from WLAN0 to ETH0 as follows: sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE sudo iptables -A FORWARD -i eth0 -o wlan0 -m state --state ...
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Preserve NAT mappings across reboot

My Linux router is able to reboot and reconnect all network interfaces pretty fast (~10 seconds, thanks to systemd and a SSD disk), and comes up with the same IP addresses. Unfortunately the reboot ...
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Trouble with last DROP rule in iptables

Let's say I want four ports to be opened for any incoming packets so I made this ruleset: #> iptables -L -v Chain INPUT (policy ACCEPT 20 packets, 1190 bytes) pkts bytes target prot opt in ...
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151 views

Make application use specific network interface

I have an openvpn connection and I need it to work only for one application, this app uses an specific local port. I used route-nopull on my openvpn config file and then: ip route add default via ...
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1answer
50 views

Filtered port with virtual server setup on a NAT

I have a Symphony SY602 ADSL router and I want configure a dynamic DNS to access my system remotely. I made a NAT virtual server in routers configuration and this is what I configured: Server Name ...
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1answer
308 views

How to force Google safesearch on entire network

I've a problem filtering web searches on Google domains. Currently I've a linux openVPN Server running with openDNS "family block". I can block a lot of websites with dangerous content and it's ok. ...
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OpenVPN won't connect from remote location

I set up OpenVPN on a linux machine in my basement. I'm able to connect from my Windows 8.1 machine without an issue when I'm connected to the local network. In this instance, I set the config file ...
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203 views

allow incoming ssh with openvpn client

I have set up an OpenVPN client on my home router. The moment the tunnel goes up, I can no longer ping my router from the internet using its WAN_IP. I would like to allow certain incoming connections ...
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How can I efficiently filter Dos packets? [duplicate]

I have recently been the victim of some Dos attacks. The facts : I received a very high amount of packets saturating my connection and preventing me from accessing the Internet during one hour ...