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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With iptables only allow certain outbound ports

Okay, I'm running a router with shibby tomato (linux based) v1.28-115 and have a bridge network setup (br1) that consists of a guest wifi. I want to only allow access to specific outbound ports... ...
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381 views

Chromecast, Unblock-Us and Edimax BR-6478AC router

It seems that Google has hard coded the Google DNS into the Chromecast, thus making it pretty much useless for anyone outside the U.S. who wants to use it for Netflix and Hulu. I have the above ...
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81 views

Drop IP fragments of a certain protocol

When conntrack is active, the iptables stack never sees a fragmented IP packet, only the reassembled one (source), so the -f test never matches. If I want to block any fragment I could set ...
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173 views

Disable SSH remote tunneling

I need to restrict SSH tunnel functions. Users should not be allowed to create remote tunnels but only tunnels to localhost. I tried to setup the whole thing in the SSH configuration but I can only ...
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2answers
1k views

CentOS 6.4 and alternate SSH port not working

I've got a CentOS 6.4 machine and would like to change the default SSH port, and followed these instructions: CentOS Wiki After making those changes (including the "semanage port -a -t ssh_port_t -p ...
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419 views

Internet access to host behind firewall using ssh tunnel

My goal is to give host behind firewall access to the internet. Below you can find brief description of network [internet] <-> [proxy] <-> [A] <-> (firewall) <-> [B] [A] - ...
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Source Based Policy Routing & NAT (DNAT/SNAT) aka Multi WANs on CentOS 5

Originally posted at Unix and Linux but nobody was able to answer it, so m migrating the question here: My question is regarding Source Based Policy Routing on CentOS 5 with 2 WANs plus a LAN (NAT) ...
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1k views

Forward connections on 0.0.0.0:80 to 127.0.0.1:9091

I'm trying to set up a tor-relay. In order to allow tor to present a static web page explaining what it is I want the server to listen on port 80 and 443. In order to allow tor to use ...
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426 views

OpenVPN + Squid or another way of blocking advertisements/websites?

I have a personal VPN that I use on my tablet for public wifi protection. Adblock+ is limited on android in that you need to set up a proxy for it to work, and this isn't ideal. Before I started ...
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204 views

ICMP firewall policy for standard ubuntu desktop

For a standard desktop computer running Ubuntu 12.04 behind a NAT router, what ICMP packets should one accept in the firewall, say iptables? It seems there is often conflicting advice; some say block ...
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597 views

How do I route a port range in a linux host to a guest VM?

I am trying to redirect a certain port range in a linux host to one of its guest VMs. I would like for this redirection to apply to all the host's interfaces, including localhost. I was able to do: ...
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2k views

iptables rule for loopback interface lo

I want to test some network performance, where I need to use a tcp client to connect to a tcp server program on the same host, so I used localhost(127.0.0.1) however, when the TCP SYN is sent, it get ...
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1k views

Can't connect to SSH over VPN when using 3G only

I'm having a bit of a strange problem that I'm not sure how to debug/fix. I have a Raspberry Pi connected to a Windows VPN via either a wired interface or 3G dongle. With the wired interface I can ...
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2answers
994 views

IPtables Rules to Block IP Range

I've applied the following rules from a text file called "iptables.save" to iptables. But to my dismay, I found that the ip address 107.22.26.176 is still able to access my server via TCP. What did ...
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721 views

How to test IP Tables Rule (Linux Ubuntu12.04)

I wanted to ask how to test IP Table Rules. For example, I have a port number and I want to be sure that it accepts all packets. How can I do it? After I type iptables -L I see that the rule has been ...
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505 views

What is command to look list of redirect rules, iptables

im using command like this : iptables -t nat -A PREROUTING -p tcp -d 192.168.1.118 --dport 4080 -j DNAT --to-destination 192.168.1.118:4088 My question what is command to look all rules in the ...
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2k views

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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693 views

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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504 views

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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309 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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437 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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703 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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329 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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114 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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661 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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765 views

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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3k views

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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308 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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368 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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303 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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950 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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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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155 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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256 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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22 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 ...
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44 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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26 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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26 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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62 views

Iptables rules to only whitelist SIP providers

I have an Asterisk box sitting behind an ADSL router/modem. There are no other services on the Asterisk box, just telephony. I am getting a lot of traffic which I think are SIP probes. I've ...
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207 views

How to forward traffic using iptables rules?

I am new to iptables and I have been doing Google searches for a few days now without finding a good solution to this problem. I have computer A with a public ip address (say 192.0.2.1) that can ...
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39 views

Add IPtables rule by script at the request of another computer

I wonder, is it possible to make an script, which adds rule in iptables by request from other pc? I mean, script "knows" what to do, but addres for rule comes from request. And how do you think it ...
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44 views

Bitbucket SSH and iptables

I'm a newbie in iptables to be honest. I have some basic rules. Everything is blocked by default. iptables -t filter -F iptables -t filter -X iptables -t filter -P INPUT DROP iptables -t filter -P ...
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Iptables error :libipt_cgroup.so doesn't exist while using net_cls.classid in net_cls cgroup subsystem

In kernel document doc/cgroup/net_cls.txt, it introduces the function of net_cls.classid, and show an example of netfilter (iptables) using this tag to perform actions. the command of iptables is: ...
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27 views

Transparently proxifying certain devices on the network

I'm using my computer as wireless access point and router to my home network using hostapd under Ubuntu 14.04. I want to transparently proxify certain wifi devices in the network (identified by their ...
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642 views

iptables blocking all traffic even with ports opened

Simple as I can put it: I can't access my servers with iptables enabled, with default rules. Need to disable iptables to get access. Trying to find the cause. Only difference in setup type is layer3 ...
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102 views

Can't connect to web server from outside my network

I have a Debian-based server that I would like to be able to access from the Internet (no domain name yet, I'm just trying to get it working for now). I already have port forwarding set up on my ...
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131 views

Conntrack/NAT's port mapping for a specific port breaks whenever that port's service is shutdown for too long. How can I fix this?

Linux Gentoo 3.13.6-hardened-r3 #1 SMP Sat Apr 12 09:17:25 EDT 2014 x86_64 Intel(R) Core(TM)2 CPU 6300 @ 1.86GHz GenuineIntel GNU/Linux hardened with grsecurity and selinux with a strict policy in ...
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99 views

Segregating/Separating a device (ATT 3G Microcell) from internal network without using DMZ

I would like to put the ATT 3G Microcell in an isolated network from a network that has the rest of my devices, by which I mean I want the ATT 3G Microcell to only be able to access the Internet, but ...
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95 views

How to stream WiFi cameras over a Linux gateway to my laptop using iptables?

My setup is as follows: Linux gateway has one WLAN configured as WiFi client (192.168.0.100) to a Linksys WiFi AP(192.168.0.1). There are three WiFi cameras connected as WiFi clients (192.168.0.101, ...