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 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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525 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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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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6k 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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35 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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90 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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347 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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363 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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195 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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29 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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222 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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47 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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102 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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227 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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96 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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5k 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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273 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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33 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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501 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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213 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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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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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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124 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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80 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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411 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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65 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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36 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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470 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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81 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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136 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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196 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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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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76 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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109 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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163 views

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 ...
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How to permanently disable firewall in Red Hat Linux

I have followed the below steps to disable the firewall in Linux. After reboot, again firewall is enabled. How to disable firewall permanently? Login as the root user. Next enter the following three ...
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716 views

Iptables, allow common ports, block the rest

I want to allow people to connect to ports 22, 80, and 443. Also I want to be able to do DNS lookups from my server. Here's what I'm trying: iptables -A INPUT -m tcp -p tcp --dport 1 -j ACCEPT ...
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159 views

iptables does not seem to be applying SNAT to packets sent on a raw socket

I'm writing packets from a user space program to my wireless interface wlan0. I've set up a SNAT rule with iptables as follows iptables -t nat -A POSTROUTING -o wlan0 -j SNAT --to 192.168.1.3 And ...
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120 views

Open ports in Ubuntu 13.10 server

Im setting up a realtime gameserver fps-game, and then i need to configure ports. Just to mention, i will setup multiple servers for this game on the same ip address, which means i must open multiple ...
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254 views

Restricting access to iOS apps based on time of day

I'm looking to set up something on my iPhone and iPad that works like SelfControl on my Mac. I get distracted by Facebook, and would like to restrict my access to it except during certain times of ...
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1answer
754 views

OpenWRT Firewarll INPUT Chain allowing everything?

I haven't done anything to my the default firewall rules except open a port for ssh from the wan and add the rules for OpenVPN as defined in this tutorial: ...
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547 views

Intermittent disconnections when using OpenVPN over SSH tunnel; possible iptables issue?

I've recently set up a Debian Wheezy server with OpenVPN to help out some friends in areas where internet censorship is a problem (including the blocking of VPN traffic in general). To overcome this, ...
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1answer
112 views

Port Forwarding with the real IP-address

How to implement port forwarding, so that would be displayed on the host real IP and non-IP machine, as it comes with SNAT DNET with IPTABLES The scheme is about the The machine-HETE with IP ...
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54 views

CentOS - ipTables

I have some questions about ipTables. Is it possible to open all ports between 2000 and 6000 and then have 2245, 5435,5434 closed? Is it possible to open some ports from a ip address? Eg. The only ...
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655 views

CentOS 7.x iptables

I have manually edited the /etc/sysconfig/iptables file in my CentOs 7.x installation , I have two entries and two processes running at the respective ports. I am able to telnet/access port 2181 but ...
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63 views

Need help converting some linux commands to OSX

I want to convert some linux commands into OSX. (Mavericks 10.9.4) root@bt:/# /etc/init.d/apache2 start (will "sudo apachectl start" do the same?) root@bt:/# echo “some Site Goes Here!” > ...
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488 views

squid proxy slow response

We are using the squid proxy in our setup and implemented as transparent proxy with user authentication. Before couple of days, while we are trying to setup the iptables the squid started performing ...
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260 views

How to correctly configure iptables on a laptop?

I have run these commands (tried switching the order too) because I want to set up a firewall on my laptop so that nobody can connect to it (except of course in response to a connection I've made): ...
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211 views

Why doesn't SpeedTest.net Upload work in Windows when using a Debian-router?

There is a FTTx connection. I connect ISP cable to the WindowsXP pc, setup PPPoE. SpeedTest.net shows normal Upload / Download. Now I connect ISP cable to router with Debian 7.5 installed, set up ...
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1answer
282 views

ip6tables: how to handle periodically changing prefix?

My ISP provides me with native IPv6 (unfortunately DS-Lite for v4) and I'm using SLAAC for the clients in my local network behind a broadband router. As I don't trust the router (which is configured ...