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 to open ports for localhost on linux?

I've been reading for the past hour about opening ports on Ubuntu 12.04 and I can't seem to get anything to work. I'm running a program with an RPC server accepting local connections on localhost ...
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Blocking all sites/IP address but Google.se with iptables

Im trying to block all IPs but Google.se. It doesnt work (Site does not display) Here is what I wrote: #/bin/sh echo "Flushing IPTables..." sleep 1 iptables -F iptables -X iptables -t nat -F ...
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How to use NAT iptables rules for hostapd

My PC is equipped with two net interfaces - wlan0 and eth0. I want to use WiFi port as access point on wlan0. So i use hostapd facility and it works properly in routing mode in local network. Users ...
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364 views

iptables: how to allow genuine internal traffic whilst blocking spoofed/bogus packets?

So I've read that a common attack is spoofing packets from internal SRC IP addresses, such as 192.168.0.0/16. How can I defend against this with iptables, yet at the same time allow traffic from the ...
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Nginx works on my linux machine but is not accessible from other computers in my local network

In my LAN network I have a server with Scientific Linux (RedHat or Fedora based distro), I've done yum install nginx but the welcome page is not accessible from other computers in my network. When I ...
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I need some help proof reading my IPtables rules, my rules seem to work but I cannot be sure

Like the title says, I need some help proof reading my iptable rules, my rules seem to work but I cannot be sure. My set up is as follows: ISP ---> cable modem ---> Ethernet switch ---> ...
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874 views

Manually Editing iptables

I'm using CentOS. What I'm wondering is, what happens if I manually edit /etc/sysconfig/iptables and save it? Is that the definitive source? When I type iptables -L I get something that doesn't match ...
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211 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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491 views

NAT router sends RST to a server where a NAT'ed client is connected to

As I tried to remove some Ethernet wires in my home network, I took an older notebook with Linux and tried to use it as some kind of Ethernet-2-WiFi-NAT-router (Wi-Fi card can't act as bridge, so I ...
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108 views

Lubuntu UFW does not respond

I have been using ubuntu for a long time. Nowadays, I wanted explore lubuntu. However, I cannot configure ufw. Actually I can but it does not respond. Basically, I cannot get the result of "ufw ...
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606 views

iptables, redirect from ip address to loopback

I have an Apache web server listening in 127.0.0.1:63280 eth0 has IP: 172.200.200.200.1, and try to connect from workstation IP 172.200.200.200 iptables -t nat -A PREROUTING -s 172.200.200.200.1 -p ...
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Prevent device from reaching WAN traffic (MAC address for example) - OpenWRT

I want to forbid a device on my network from accessing the internet. Computers still have to communicate with the device, and vice versa. OpenWRT version: OpenWrt Attitude Adjustment 12.09
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1answer
467 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
302 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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204 views

Change UDP port with iptables for VPN clients

What I want to do is say that for all UDP connections on interface ppp0 that have a destination port of 53, change that destination port to 1053. I am attempting to change the destination port of UDP ...
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1answer
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Iptables drop forward packets to specific host

I am having trouble isolating a specific host from others on my lan. What I am trying to do is only allow communication between 192.168.0.2. and 192.168.0.8 as well as not allow any other host to ...
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No idea what is listening on port 80 in OS X

I'm on OSX Mountain Lion 10.8.3, and I've freshly rebooted my Mac. I want to start a service (like Apache on port 80), but there is already something going on with port 80: telnet localhost 80 ...
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265 views

How do I drop the entire INPUT chain from iptables?

On Linux, I've been building a malicious IP list. I assume the DDOS is now gone. How do I drop the entire INPUT chain from iptables, without affecting the FORWARD or OUTPUT chains?
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127 views

Linux gateway / DNAT: restrict to certain interfaces

I have various machines with a number of network interfaces: eth0: a local LAN eth1: sometimes used for the connection to the Internet gateway ppp0: Modem uplink as an alternative to eth1 tun0: ...
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1answer
356 views

Allow shell access for key holders OR password login for whitelisted IP addresses

As a first line of defense against brute-force attacks, I've restricted SSH login attempts with TCP wrappers (denying access by default, and maintaining an IP whitelist in /etc/hosts.allow). However, ...
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1answer
2k views

Limit UDP outbound traffic to loopback (localhost) instead of eth0

Atm i'm testing it on Ubuntu Server at VMware Workstation + Windows 7 local host with bridged connection. Later this has to go to live server. I have VLC streaming video file on Ubuntu with cvlc ...
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Problems in creating rules in iptable

Hello to all :) I need a little help with creating a rules. Im starting to learn iptables and firewalls but I have some questions. I need to allow HTTP communication only from PcA to PcB./ My code is: ...
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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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307 views

Updating iptables via ddclient

TL;DR Is there anything I can do to change iptables from ddclient (with user ddclient)? The story behind I have a computer that uses dyndns to be addressable from outside. Whenever the provider ...
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1answer
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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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Iptables configuration to allow Steam Client

I recently got and setup a small linux (Debian) router box. I'm adding it to an existing network to create a small subnet with specific properties, namely internet content filtering. I'm highjacking ...
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1answer
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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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1answer
239 views

How to drop IP packets received on the default route interface when no other than default route is found?

I am setting up a router based on a linux kernel. As expected, ipv4 packets received on the interface used by default route are sent back to the same interface in case no other route is found. Is ...
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How does iptables masquerading allow to access a different local subnet?

My Linksys router (IP 192.168.1.1 inside a /24 subnet) is connected to my ADSL modem (IP 10.0.0.138 inside a /24 subnet) to establish an internet connection via PPPoE. To be able to access the modem's ...
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3answers
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linux routing outbound port 80 traffic via ssh tunnel, iptables, or a simple route

I have two hosts, A and B. Host A hosts services on port 8080 and has outbound internet firewall rules allowing port 80 and 443 access to Host C. Host B is on the same subnet as Host A. Host B is ...
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using iptables to prevent RST related to a specific port

I have a program which uses libpcap to capture incoming TCP SYN packets, these SYN packets are destined for a specific port. But I have no tcp listening socket for that port, so in practice, the OS ...
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iptables rules are not in action

I have a iptable rule file, on the INPUT chain I have -A INPUT -i em1 -p tcp -m tcp --dport 54000 -j ACCEPT -A INPUT -i em1 -p tcp -m tcp --dport 30000 -j ACCEPT -A INPUT -i em1 -p udp -m udp --dport ...
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Advanced QoS on prioritized first packages set by ISP

I have the following problem my ISP (Fibertel from Argentina) accelerates, 'enhances' the first 6.8 megabytes of downstream transfer and it's seems the first 1.8 megabytes of upstream transfer. This ...
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1answer
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allow redirects with iptables

with the following rules, php can't make a redirect to another file. it's freezes at the point when it gets toheader("Content-type: video/x-flv"); header("Location:" . $VIDEO); or ...
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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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1answer
817 views

How to allow access to only specific IPs with Parallels VZ built-in firewall?

How can I use Parallels Virtuozzo's built-in firewall utility (called psa-firewall under the hood apparently actually psa-firewall seems to be a seperate Plesk interface - either way, it's basically a ...
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1answer
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How can I add the port to iptables rules on centos?

I want to open the port 8040 on my centos, but I keep getting connection refused. This is what I have done: iptables -I INPUT -m state --state NEW -p tcp --dport 8040 -j ACCEPT iptables -I INPUT -m ...
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Iptables: Allow Internal LAN to access INTERNET

I have an internal network behind my router on eth0, and I have my router connected to the internet thorugh wlan0. I can't access the internet from inside the lan, how can I fix this? wlan0: ...
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1answer
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Configure IPTables [duplicate]

We have RHEL 5.0 squid proxy in our office. Our LAN is 172.20.12.0 /24 n/w. Proxy ip is 172.20.12.4 /24 . I want to share Internet through proxy. Most importantly: Suppose I have flushed the ...
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1answer
828 views

LInux squid proxy

We have RHEL 5.0 squid proxy in our office. Our LAN is 172.20.12.0 /24 n/w. proxy ip is 172.20.12.4 /24 . I want to share internet through proxy. Most importantly: I want to give full access to ...
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1answer
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iptables status enabled after restart even after disabling

I am disabling iptables on Oracle Linux 6 with these commands. setenforce 0 service iptables stop service ip6tables stop chkconfig—level 123456 iptables off chkconfig—level 123456 ip6tables off ...
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1answer
2k views

UDP packet and firewall

I notice when I send udp packets from computer A to computer B, B can receive the upd packets correctly but if I send udp packets from computer B to computer A the udp packets are not received A and ...
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2answers
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unable to connect to localhost:80 after installing nginx

I just installed nginx by doing sudo yum install nginx and I'm unable to connect to it on port 80. I tried stopping iptables by doing sudo service iptables start and was still unable to connect. I'm ...
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iptables simple forwarding setup woes

I have iptables running on a host (acting as a firewall) in a Linux namespace with only one network interface: h2-eth1 (has an IP and MAC address) I have set up my switch to forward all packets to ...
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show interfaces in iptables -L

Is there a way to show the network interfaces via iptables -L in Ubuntu 12.04? When I execute an iptables -L I get an output like this : Chain INPUT (policy DROP) target prot opt source ...
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1answer
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Port-Forwarding for Click'n'Load remote usage

I've got JDownloader running on my HTPC and access it via VNC. The problem with Click'n'Load (CNL) is, JD only listens on localhost:9666 for incoming traffic, and the browser applications only send ...
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1answer
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Linux iptables forward from ip1:port1 to ip2:port2

I connect thought tunnel to other machine like this: ssh user@ip -L2000:192.168.64.88:80 So on my local machine I want to configure iptables that way like I have a "native" access to ...
2
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1answer
298 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 ...
2
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1answer
3k views

OpenWrt: how to give wlan clients @ 10.x Internet access via gateway @ 192.168.1.254

I want to isolate guests connecting to my Wi-Fi to the 10.0.0.x subnet, while giving them Internet access. The OpenWrt router is at 192.168.1.48 ("wifi" interface has 10.0.0.1) and my gateway is at ...
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iptables - add rules not as root

One of our servers is being hit daily by a large number of spam bots. They're not able to post any spam, but they still try and end up slowing down the server for real users. To counter this, I have ...