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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How do I share my wlan0 internet connection to eth0 using command line and config files?

I understand how it is done using the GUI (1, 2, 3), but I need to do this manually using Linux tools/commands (iptables, eatables ...). What are the configuration steps and commands to use, ...
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Why am I getting “FATAL: Ident authentication failed for user ”root“” after changing rails server to port 81

I was running my rails app on the default port of 3000. I opened port 300 with: sudo iptables -A OUTPUT -o eth0 -p tcp --sport 3000 -m state --state ESTABLISHED -j ACCEPT and sudo iptables -A ...
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3 views

SSH tunnel data from hostapd server to remote server

I've set up a small raspberry pi with hostapd to be a wireless access point. I'd like to have all connections from it ssh tunneled to a server in another country. I'm not overly sure how I'd do this, ...
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27 views

Route all packets on port 80 from inside a vm to kali linux on another vm

I'm trying to route all packets on port 80 to kali linux so that I can ssl strip them but I cannot see to setup the iptables correctly to force all the packets to go to my other Vm. [ Virtual Machine ...
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1answer
17 views

iptables on debian blocking git pull, http api requests etc

I am using IPTables on an API server to block all incoming traffic except for SSH, HTTP and HTTPS. I need to have full access on the loopback interface to run beanstalkd amongst other things, and need ...
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1answer
35 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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1answer
39 views

Why my iptables configuration for port-knocking does not work?

I implemented the following iptables rules on my test server for a course. The firewall shuts down and I cannot access port 22. However, after knocking on the ports 1111, 2222 and 3333 in that order - ...
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71 views

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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12 views

iptable definitions for routing and defence

I'm attempting to configure a firewall on my laptop that allows for routing. The main trick is, I don't want to allow for connections to be made that do not fall under the ESTABLISHED,RELATED ...
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18 views

Port mirroring without TEE

I have a home router running OpenWRT 12.09.1. The package list for this version does not have iptables-mod-tee. I am familiar that I could set up a port mirroring using: #-A POSTROUTING -t mangle -o ...
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11 views

Trying to configure iptables on Slackware 10

I am trying to configure iptables on a Slackware 10 machine. This Slackware version is required in my class - so I cannot upgrade it. After compiling it, I want to configure iptables - however, it ...
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44 views

Conntrack gets incorrect forwarding rules for outgoing protocol 41

I'm trying to forward protocol 41 (ipv6-in-ipv4) for an HE tunnel through a WRT54G running Tomato 1.28. Tomato 1.28 is running a 2.4 kernel that knows absolutely nothing about protocol 41, except that ...
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1answer
70 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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1answer
32 views

Using IPtables to redirect IP address range to port range

I'm trying to set up an IPtables rule that will forward all packets to a /22 range to a single IP and port for debugging purposes. Based on the question here Using iptables to redirect ip address I ...
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16 views

Becoming a VPN router in Arch Linux

I want to be able to set my computer as the router (or "default gateway") on any device on my network and have it go through my VPN, eliminating the need for a VPN client on that device. I do echo 1 ...
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28 views

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 ...
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1answer
40 views

Iptables to forward HTTPS traffic to remote HTTPS proxy

My goal is to use Iptables to take all traffic going to my server on port 443 and forward it to a remote HTTPS proxy server. So basically if I was to use my ip of 192.168.1.142:443 as a SSL proxy it ...
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21 views

Open ports for Age of empires in ubuntu router using iptables

The purpose of this question is to learn how to correctly use iptables. As I am currently living in the dormitories in the University and I am using a small netbook as a router to provide wifi in my ...
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20 views

Special type of DMZ?

So I have a standard modem-router setup all great to go, my Modem gives an IP Address from my provider via DHCP according to my Mac address. All is good. However, I now want to expose a new virtual ...
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1answer
20 views

Set block time with iptables

I have the following rules in ufw, for iptables: -A ufw-user-input -p tcp --dport 80 -m state --state NEW -m recent --set -A ufw-user-input -p tcp --dport 80 -m state --state NEW -m recent --update ...
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1answer
37 views

Will an inbound iptables rule in ddwrt on port 443 break https?

I want to run a vnc repeater service on my home ddwrt router. Due to the possibility of friends/family asking for support in unknown network environments, I'd like the host-repeater application to run ...
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1answer
51 views

No internet through OpenVPN

I am having trouble with my OpenVPN setup. I have a Linode box with an OpenVPN server installed on it and I managed to get Tunnelblick to establish a vpn connection from my mac. I followed this guide ...
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1answer
181 views

IPTables module ip_tables not found for root

We got a custom build Linux distribution from a vendor, which is not shipped with iptables enabled. root@xxxx:~# iptables -L modprobe: FATAL: Module ip_tables not found. iptables v1.4.21: can't ...
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45 views

Iptables redirection to squid proxy server

I'm trying to setup filtering through a squid proxy however I'm having trouble getting my router to send all traffic to the proxy using iptables. I've currently got it setup such that there is the ...
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26 views

Iptables intercepting traffic

I have 3 servers on the network (Server 1: 10.0.0.1, Proxy server: 10.0.0.2, Server 3: 10.0.0.3) and I would like to intercept the traffic going through the proxy server from Server 1 to Server 3. ...
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31 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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1answer
21 views

iptables - I'm losing control over the box by adding new rule to the config

My set up is the following: Internet uplink (200Mbit) DMZ (1GB ethernet) Internal network (1gb internet) Log interface My gateway is serving around 600 clients with 1400 iptables rules in ...
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2answers
82 views

Is it possible to force DNS for certain devices with iptables?

I'm trying to use iptables to force DNS for certain devices (Shibby Tomato on Asus RT-N66U). I haven't found anything online describing such a configuration. The closest I could find was this: # For ...
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81 views

Configure iptables firewall to allow DHCP, DNS, HTTP, SMTP, FTP, IMAP, POP, and Squid ports – deny all other services.

Configure iptables firewall to allow DHCP, DNS, HTTP, SMTP, FTP, IMAP, POP, and Squid ports – deny all other services. 1 pc for router ( place firewall) 1 pc for server ( place web,dhcp,ftp,etc)
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160 views

iptables not starting on CentOS 6

I am running CentOS release 6.5 (Final) and cannot figure out why my iptables is not starting. I may have executed some other command to permanently prevent the start up of iptables; I do not ...
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108 views

Difference between iptables default policy to `DROP` and inserting a seperate policy in input chain to DROP all connections

I'm trying to DROP all incoming connections to my server, except from particular networks. At the same time I want to keep all outgoing connections from my server to external network (any network over ...
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1answer
47 views

Iptables redirecting

I have set up a Personal hotspot using Hostapd. But this hotspot is not connected to the internet but I do have Apache installed on it. What I am trying to achieve is to redirect all the clients (that ...
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1answer
18 views

iproute2: How do i connect one machine to the internet via another

I have the following setup: A > 169.254.8.125/16 <--(ad-hoc)--> 169.254.9.109/16 < B > 192.168.178.21/24 <--(wifi)--> 192.168.178.1/24 < AP/router > internet I want to connect A to the ...
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4answers
55 views

IPtables keeps resetting rules and blocking almost everything

Every time I reset IPtables, the rules keep coming back in about 10 minutes, blocking everything besides port 22 and 80. When I do a "iptables-save", I see this I can't find out where it's coming ...
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47 views

cant run php FastCGI in arch

I have a PhpStorm IDE in Manjaro(Arch base Linux). I install php and php-fpm from repository and config PhpStorm with php. PhpStorm can know php and that version. but when i run my php code in ...
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1answer
16 views

iptables and router port forwarding

I need to access my home computer remotely using ssh. I have port forwarding set up on my router to send me to the appropriate computer on the local network. I have it working but viewing my home ...
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33 views

getting request into lxc-guest via host firewall but no answer (openvpn inside lxc)

my goal is to set up openvpn inside an lxc-container and i came close but it could not manage to get an answer out of the host. The Setup Host: public ip: 88.88.88.88 (on eth0) LXC-Gateway: ...
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20 views

IP rule table look up does not seem to work

I have a sytem with three network interfaces. Below is the configuration that I'm trying to set up. wlan0 (its actually an WiFi AP interface) - other devices connects via this interface. net1 - ...
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1answer
63 views

Expose a Reverse SSH Tunnel on the Remote server

I set up a Reverse SSH tunnel from my home computer to my work server: ssh -f -N -R 19999:localhost:22 remoteuser@server To connect to my home computer I have to first log in to the server and then ...
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1answer
31 views

confusing INPUT,OUTPUT iptables rules

Following is my iptables rules in Ubuntu. ╰─$ sudo iptables -S -P INPUT ACCEPT -P FORWARD DROP -P OUTPUT ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT -A ...
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2answers
65 views

How to block sites like facebook.com, google.com etc. for different users

I use iptables for other sites as: iptables -A OUTPUT -o EXTERNAL_IF -m owner --uid-owner USERNAME -d DESTINATION_WEB -j REJECT It works for most sites except ones having a large range of IPs. What ...
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37 views

Meaning of Bridge-Check in iptables flowchart

In the famous iptables flow-chart what does bridge-check exactly stands for ? I couldn't find any documentation. The only clue I found was while scanning the MikroTik RouterOS documentation ( ...
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1answer
77 views

Most secure way to have IPtables auto-loaded using Debian / Linux

I'd like to know the safest way to load iptables using Debian. Of course, I can use a script that uses iptables-restore : #!/bin/sh iptables-restore < /etc/firewall.conf but : 1) where is the ...
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26 views

Is it possible to know a user logged in on Ubuntu instantly?

In fact, I am trying to restrict access to some websites for different users. I asked the question: Restrict access to some websites for different users. The given answer is ok; but as the owner ...
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40 views

Output port redirect with firewalld?

I'm used to iptables and I can't find a way to do this with firewalld. I need to redirect the output traffic of one port back inside in the same port, basically this: iptables -t nat -A OUTPUT -p tcp ...
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1answer
23 views

How to apply ipfw rules to domains that resolves to multiple IPs?

Suppose I wanted to use ipfw to throttle uploads to youtube. The uploads are made to upload.youtube.com but this domain resolves into multiple different IPs (which also appear to change over time). ...
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67 views

not all packets forwarded by pptp VPN server

I have the following setup: +------+ +---------+ ppp0---------+ |router| | A +-----+---+-----+ B | | R | ...
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1answer
35 views

Route traffic to a destination to another destination using iptables

How to route traffic to a destination to another destination and receive response using iptables I have two vps on cloud. Lets say VPS-A and VPS-B. If a request to 8.8.8.8 generated from VPN-A, I ...
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42 views

Forward traffic from specific ip addresses to another port iptables

I can't figure out the syntax to forward TCP traffic from specific ip addresses to another port using ip tables. Lets say I want any TCP traffic from 1.2.3.4 to port 80 to be forwarded to port 81. ...
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Site to Site VPN - Openswan and CISCO A2A

Below is the diagram that the VPN connection between Openswan server and CISCO A2A. client A and B are remote hosts with static ips. client X and Y are behind the Cisco firewall. I can see ...