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 can I port forward an LAN port to a WAN Ip with iptables?

Using iptables on my router (dd-wrt), I'd like to forward requests to the router on port 64738 from the LAN to an IP (192.168.10.14) on the WAN. This is the opposite of the norm (forwarding a request ...
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413 views

Limit bandwidth on HTTP downloads based on file size

Is there a way to limit lets say in iptables or any proxy solution/software if a user is downloading a filesize that is greater than lets say 20MB it will limit his entire download at 2KB/s? ...
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1answer
235 views

amule, Fedora 14, iptables

I need to set iptables rules for aMule, but I am not sure which one are the right ones. Googling around, I have seen something like: iptables -I INPUT -p tcp --dport 4662 -j ACCEPT iptables -I ...
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1answer
285 views

Why does Firefox need a loopback connection?

I was playing around with firewalls and iptables. When I blocked any traffic except HTTP and DNS I was able to establish a connection to google.com via wget google.com. But I wasn't able to open ...
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345 views

Centos iptables blocks after reboot

I have a Centos5 installation with kvm on my server. I am using nat portforwarding to ssh my virtual machines. I have several iptables rules and saved then in /etc/sysconfig/iptables. After reboot, I ...
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1answer
284 views

dd-wrt: Keep source ip after port forward

I just started using dd-wrt on my wndr3700, but now all my incomming connections to a server inside the network gets the same source ip as the router. How can I change this back so I get the real ...
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1answer
4k views

Reverse Proxy for TCP (RDP, VPN, etc) and HTTP

I have a domain that points to my ISP assigned IP though a CNAME (cname goes to my noip address incase my ISP decides to change the IP), I would like to route different subdomains to various IP:PORT ...
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1answer
2k views

Match multiple strings in iptables

I have 2 strings, and i wish to queue the packet if it contains both the strings ( something like ("jsh"&&"gjhyg")), i tried following ways, but they don't seem to work: sudo iptables -A ...
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Gateway on a virtual network interface used by LXC guests

I'm currently having some problems with configuring a gateway for a virtual network interface. Here is what I've done : I created a virtual network interface : # brctl addbr lxc0 # brctl setfd lxc0 ...
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3answers
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iptables firewall only allows internet traffic if source port of 80 is allowed

I am configuring an iptables firewall, currently just to allow http and https traffic. It is working but under a particularly strange rule - I must allow incoming connections with a source port of ...
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2answers
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Using iptables to selectively route outgoing requests?

I'd like to set up my Dd-WRT firewall so that it uses the VPN service from a VPN provider to access a bunch of destinations and normal route foe all other requests. In detail: giganews.com would be ...
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546 views

Why does my Tomato router seem to behave badly as time passes

I've set up a Firewall script on my Tomato router (a WRT54G 2.0, actually) that seems to behave correctly at start, but after one or two days, it seems that the script does not work anymore... The ...
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1answer
4k views

DD-WRT firewall rule configuration

I'm using DD-WRT on my linksys router. I want to limit each user on my network to 200 connections at any given time. Does anyone know the rules I enter the firewall in DD-WRT admit panel. I tried ...
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4answers
476 views

Block all but http traffic on a network interface

I've got two network interfaces on an Ubuntu machine which go out to two different networks but both have internet gateways. I need to limit it so that any outgoing http requests it makes (ie ...
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1answer
292 views

Restrict the number of http and https connections from a specified IP address to ten connections per minute

How I can restrict the number of http and https connections from a specified IP address to ten per minute usingiptables commands? I’ve tried this but it is not working: iptables -A INPUT -s ...
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2answers
10k views

Block all ports except SSH/HTTP in ipchains and iptables

How can I block all ports except ssh (port 22) httpd (port 80) using iptables and iphains?
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2answers
1k views

How to “shut off” all networking on Linux from bash?

I'd like to write a bash/shell script that "turns off" the machine's ability to communicate over it's network card, effectively shutting down all networking. From the command line: # To turn all ...
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1answer
21 views

ip6tables causing slowness

When running commands like ntpq -p or apt-get update it takes a very long time to display the results. If I remove all the ipv6 rules, everything works fine. I checked syslog, and there's no iptables ...
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Need an explanation of iptables rule

Can anyone help me understand the below iptables rule? iptables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP
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1answer
2k 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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1answer
5k views

iptables duplicate traffic to another ip

This blog post has a template iptables rule to forward traffic, to and from the router to another ip address. iptables -t mangle -A POSTROUTING \ -d [IP to spy on] \ -j ROUTE –tee –gw ...
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244 views

How iptables behaves on timezone change?

I have doubt how iptables keep changing the info in iptables when timezone is change. I am using iptables s v 1.4.8 I have blocked one IP with following details # date Thu Jun 6 12:46:42 IST ...
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iptables LOG actio writes to STDOUT

when I use LOG action in some chane of iptables rules, I get the output both in STDOUT or STDERR of the xm console and in /var/log/messages. Is there way to make iptables to write only to log ...
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2answers
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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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481 views

How to block network traffic on ubuntu gateway via arp table

I have a network with 80 PC and a ubuntu 12.04 as GW. For security reason I want to limit the Computers connected on this network using an ARP precompiled table. In other words I want a tool that ...
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177 views

How to check/adjust SSH server on embedded board

I'm currently having difficulties connecting to an embedded board from my Linux machine through ssh. The embedded board is a FOX G20 V with a Linux OS. I've tried to connect to the board through ...
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1answer
1k views

How do I block every connection except vpn and ssh without endangering the state of my vps?

I have some vps space but I get alot of scans based on what I see in iftop. I tried some iptables stuff but it gets tiring and useless to put all the ips that I see in the logs. I am wondering about ...
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2answers
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Howto compile a kernel module on CentOS [required packages]

What yum commands do I need to get available packages installed on CentOS to build a iptables MATCH kernel module.
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29 views

Limit a range of ip addresses to specific ports using iptables

I am using iptables v1.4.21 on linux. I am trying to limit traffic for DHCP clients 10.0.0.50-10.0.0.100. I would like them to only have access to ports 53,67,80,443,9091,32400 using TCP and UDP. But ...
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1answer
78 views

IPTABLES Rules to rate-limit ICMP(Ping) traffic to 5 packets per second

Trying to figure out the IPTABLES rule for above mentioned requirment. Can anyone please advise me here. I was trying this but not succesful - iptables -A OUTPUT -p icmp -m limit --limit 5/second -j ...
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2answers
746 views

OpenWRT: iptables rules will be deleted automatically

In my OpenWRT instance, I have added iptables rules in the Input filter table, but the problem is when I turn on my system I found that the rules are deleted. What can I do so that the rules are not ...
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1answer
97 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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3answers
393 views

Configuring IPTables to exclude webhost from VPN tunnel

I have a Raspberry Pi running as a server for my webhost. Raspberry pi is connected to a VPN service 24/7. Due to this, I am unable to connect to my webhost using my public IP address issued by my ...
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1answer
499 views

Block traffic to LAN but allow traffic to Internet (iptables)

On my home network I am setting up a CentOS server that will be used by about a dozen or so for educational purposes - e.g. learn how to use the Linux shell and host websites, among other things. I ...
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1answer
54 views

Should my server ever need to directly communicate with the NAT gateway?

What I mean by ``directly communicate'' Does it ever need to receive packets with the gateway's IP address as the source IP address, or send packets with the gateway's IP address as the destination ...
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639 views

Is Iptables blocking outgoing ssh connections?

I have been trying to do pulls from github and it keeps hanging. My iptables rules have no rules which block outgoing traffic but I cannot connect to github using either ssh or http. I can't even ...
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1answer
100 views

Forwarding all traffic to other server with iptables

Assume I have a sever with X.X.X.X IP address and a web server with Y.Y.Y.Y IP address. How would I forward web traffic from X.X.X.X to Y.Y.Y.Y using iptables? My servers run Linux and use iptables
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502 views

bind/named not working on UDP from external

This one is weird. I've set this up a long while ago, on a centos5. From what I remember, it used to work. For some time now, it's not. I've just been informed so no clue what changed when that made ...
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2answers
2k views

Is selective VPN routing worth it?

I want to setup routing tables on my RT-N66U router to selectively route traffic through a VPN. For instance, only Pandora requests would go via the VPN. I've found a way to do this with iptables: ...
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1answer
241 views

iptables detects clients behind NAT?

I'm setting up a server that I want to protect from DoS attacks, by setting a limit using iptables: iptables -A INPUT -p tcp --dport 80 -m limit --limit 25/minute --limit-burst 100 -j ACCEPT (default ...
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2answers
2k views

Route traffic through VPN to some IPs occasionally

I would like to route traffic to some specific addresses through VPN. Easy enough, one can simply add a route: ip route add <destination ip> dev tun0 scope link Here comes the catch: I do not ...
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1answer
1k views

How to block incoming traffic on a virtual interface?

How do I block all incoming traffic on eth0:0 but keep eth0 open? What I've tried is this: iptables -P INPUT DROP iptables -A INPUT -i lo -j ACCEPT iptables -A INPUT -i eth0 -j ACCEPT But this ...
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2answers
1k views

Why nic with incorrect subnet mask can still ping the gate way?

At first, my network config was like this: $ ip a 2: em1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 3c:97:0e:bd:b1:68 brd ff:ff:ff:ff:ff:ff ...
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iptables NAT doesn't preserve remote IP

I have the iptables rules below forwarding incoming ssh traffic on port 2222 to a virtual machine running in a vmware "vmnet" network on the same host. 192.168.1.1 192.168.1.40 +---------+ ...
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155 views

DNS set correctly but website unreachable

I have the (sub)domain elo.bernardinuscollege.nl, which has a DNS A record that points to 54.225.118.87, which is correct (checked it with telnet, which indeed returns the right IP). For some reason ...
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3answers
668 views

Setting up two ADSL lines for home/business use

As a follow-up to this question which is still unresolved. I have two ADSL routers with different providers connected to different phone lines to the internet. As shown in the diagram. These routers ...
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1answer
330 views

Can't reach web server from local virtual network

I have installed a couple of virtual machines. Some uder Windows, some under Fedora Linux. On one of the Fedora machined I've installed Apache web server. I have setup server name in httpd.conf to ...
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197 views

Valid Type Of Service Values

I need to know what are valid values for TOS field in iptables. I mean when I try to add a rule with ip rule add what can I give as tos value I could not find any resource about tos value. I know ...
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1answer
430 views

How can I detect long-lived connections and mark them for shaping

I would like to detect TCP connections which have been open for more than one minute (or for greater than N bytes, or M packets), so I can classify them as bulk traffic ("downloads") and de-prioritise ...
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1answer
77 views

iptables -L lags on non localhost or anywhere address

I am trying to configure iptables for ubuntu 10.04 and I have a problem with iptables -L lagging on rows where the destination or source address is not localhost or anywhere. The following entries ...