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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rp_filter not working, still get martian errors and dropped traffic

I am using the below commands to setup test environment for traffic flow. I am using a bash shell for traffic source but would eventually be VM or container. I don't understand where the traffic is ...
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9 views

Routing between interface and OpenVPN tunnel

I have two NICs: ethernet and wi-fi. I configured an OpenVPN tunnel with route-noexec option, so the computer still uses ethernet connection by default. Now, I want to make an AP with my wi-fi card. I ...
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16 views

IPTables forward port to another ip:port but keeping original source ip

I have following iptables rules on gateway machine(192.168.0.1). I want to forward port 192.168.0.1:80 to 192.168.0.2:8080. But I need to maintain original source ip so that original server can get ...
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8 views

Ubuntu IPTables

I started hosting my game-server on Ubuntu Linux 14.04 I am having an issues ، some enemies/bug abusers log in 2+ characters in the same second then they spam a certain spell/word that lags/stops my ...
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23 views

Using iptables to redirect all traffic to local webserver

Aloha, I'm trying to redirect all traffic on my wifi router to a local webserver using iptables. I'm not sure i have got the command right and also I want to exclude the router IP (172.16.0.1) from ...
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28 views

How can I allow traffic to certain web address but restrict all other in linux

I want my linux (ubuntu 14.04 , 64 bit) system device which has a 3g card in it to have restricted access of internet . I want to build a scenario where if the card is active, the system should be ...
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14 views

How to redirect a device connected with my wifi hotspot to a localhost page

How do I redirect a device connected with my wifi hotspot to a localhost page (for example login form) Ubuntu 14.04 LTS? I tried many rules earlier suggested but no one works? Plz suggest step by ...
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Iptable entry gets vanished in an hour in oracle linux 6

I carried out the following steps to create a port-forwarding rule: sudo iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 443 -j DNAT --to $ipaddress:10443 sudo iptables -A FORWARD -p tcp -d ...
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29 views

Iptables: why my redirection doesn't work?

Linux slackware,i have put ftp server with unprivileged user running port 2121. Want to redirect all packets from 21 to 2121 so my ftp is avaliable as standard without specify the port. telnet host ...
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7 views

iptables - Add additional allowed IPs

This is what I have used as reference: http://unix.stackexchange.com/a/145933 So if I do: iptables -I INPUT -p tcp -s MY IP --dport 21 -j ACCEPT iptables -I INPUT -p tcp -s 0.0.0.0/0 --dport 21 -j ...
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drop iptables chain forward

I created the following rules (for FORWARD only): iptables -P FORWARD DROP iptables -A FORWARD -o lo -j ACCEPT iptables -A FORWARD -s ##MYIPHERE## -j ACCEPT And then I run iptables -L and get this: ...
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29 views

Send all outbound HTTP traffic from a rogue Wi-Fi router to an internal prank site

Today I discovered that my teenage son installed a rogue Wi-Fi router. It is plugged directly into the ethernet jack that I forgot was in his room. I assume he did it to bypass my internet schedule ...
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29 views

NAT with multiple interfaces

________ +------------+ / | | ...
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1answer
8 views

dnsmasq different replies based on source

I want to override the DNS configuration for some domains by using dnsmasq so that queries are forwarded elsewhere to be resolved. I can do this with this configuration snippet: ...
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14 views

IPTABLES Forwarding requests over Tinc to other Host on local network

I have a couple of dedicated servers and a few VPS boxes around the world (used primarily for office and personal email servers and other cloud storage). My ISP at home/office does not allow for ...
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42 views

Debian : Outgoing port-scans detected, what to do?

We recently received a notice from our Server-providers that they detected an outgoing port-scan from our Server. They checked for malware or compromised account, but didn't find any. All they have ...
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22 views

Can't add 81.23.228.129 to iptables because of SERVFAIL - any way round this?

I need to allow the IP addresses of proxy.sipthor.net through my firewall: nslookup proxy.sipthor.net Address: 85.17.186.7 Address: 81.23.228.129 Address: 81.23.228.150 Add these to iptables: ...
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Can't see any website hosted in a node while same issue is not present in other nodes in LAN

Recently we setup a Hadoop cluster with 10 nodes in our Office premises. All of these nodes are installed with CentOS 6. However the issue I'm facing may not be related to Hadoop and accordingly I'm ...
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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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How can i implement this iptables configuration with 2 gateways?

I'm trying to configure a firewall hardware to protect my nas. What i want to achieve is explained better with this image below: network scheme While the actual iptables config is the following: ...
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58 views

Open syncthing port on raspberry pi

I have just set up a raspberry pi with the raspbian OS. Other than installing LAMP and syncthing, I have not made many changes from the initial setup. I am accessing my raspi through SSH on LAN, and ...
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10 views

Secure settings for a personal OpenVPN IPSEC/L2TP server?

I'm trying to harden my personal server as much as possible. This is the first server I have managed, so I'm also using this as a learning experience. My setup so far: 4096 bit SSH keys SSH is on a ...
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1answer
17 views

iptables: is it possible to combine “string” and “mac” modules results?

I have a raspberry pi running dnsmasq. I configured all my local devices to use this device to resolve DNS queries. I like to block certain devices using their MAC address from certain queries. ...
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60 views

Server, laptop, router, and modem, IP addresses?

I have a simple server at home. The server is directly connected to the modem and has IP: 192.168.1.7 My laptop is connected to a wireless router, which is connected to the same modem. My laptop has ...
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126 views

Troubleshooting port forwarding

I'm trying to run a web server from my home network, but I have some difficulty reaching my server from the WAN. If you have an idea where the problem could lie, or need more information, please let ...
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8 views

DDWRT - Restricted URLs not working

I have set up URL and keyword filtering in the Web GUI. It is enabled, has the correct IP range, is saved and applied. Yet URLs range are not getting blocked. nvram show | grep shows the filters ...
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27 views

OpenVPN client on DD-WRT router. How to block all WAN traffic when VPN is disconnected?

I've successfully configured the OpenVPN client on my DD-WRT router and verified that all traffic is being routed through the VPN. How would configure it such that all WAN traffic is dropped when the ...
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14 views

Apache test screen not loading. Connection refused when connecting to public ip

I'm having problems getting Apache to work. I've followed the Amazon AWS instructions (http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/install-LAMP.html) but my computer is refusing to load the ...
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30 views

How to add virtual NICs to my linux PC, so that they expose their MACs to ISP's domain?

I have learned how to add virtual NICs to a guest system in VirtualBox, just using Shared Adapter, then all the virtual NICs and my host's NIC will appear as real NICs to the ISP. So I guess there ...
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30 views

Create rule in OpenWrt LuCi, apply saved iptables rule from command line

In the OpenWrt LuCi web interface, one can create rules but leave them disabled. I have a rule for forwarding public web traffic to one of the hosts on my private network, but I usually leave it ...
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47 views

Iptables route specific port outside VPN (Tomato router firmware)

Im trying to configure my router to what I feel is the perfect setup for me. I have managed to connect the router to my VPN-provider (PIA), and routed such that only one computer connects through VPN ...
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25 views

Is IPTABLES obsolete when behind a router?

I'm still quite noobish when it comes to networking. I was fiddling around with squid on centos and i was wondering whether turning on iptables when your centos box is behind your isp modem/router has ...
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28 views

iptables rule - SSH socks proxy

I have very basic iptable rules for my home server. Block all INPUT except SSH and a few other connections. Allow everything else. When I connect via SSH I sometimes also create a dynamic SOCKS5 ...
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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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108 views

How to isolate networks with a Mikrotik router?

I have recently got a Mikrotik router for my network, and I want to create 3 networks that are isolated from each other but all have internet access: The "main" network for PCs, etc. A network for ...
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60 views

Redirect DNS requests using a router and iptables

I have a cable-modem-router from my ISP (Technicolor TC7210Z), and a bunch of wired and wireless devices connected. I want to change the DNS configuration for all devices, but I cannot change it on ...
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30 views

Cannot connect to The Ship Dedicated Server

I am attempting to run a dedicated server for The Ship from my Ubuntu VPS. I have installed the server through srcds, and it seems to start up fine. This is what is shown when I execute "srcds_run": ...
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33 views

How to Block all inbound and outbound traffic to and from an Local IP

I need to block entire traffic to and from an Local IP on an WiFi Network, I am using DD WRT Based router, So I Can use iptables. I know the IP Of an Client on the Local Network, Some thing like ...
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39 views

Samba not accessible via Server name anymore

From one day to another, my samba share (Debian 8 with current Samba 4.1.17) stopped turning up in the windows network neighborhood (Win 10). For a few days it was still accessible by typing ...
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24 views

IPtable rule to limit number of TCP connections on my PC

I have a limit on the number of TCP connections that I can make in my network. If I make more than 100 TCP connections, I get banned for a few minutes. My GoogleChrome in linux opens a lot of ...
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87 views

Compile iptables from source make error

I'm trying to compile latest iptables 1.6, but I receive the following error: (./configure it's OK) then I call make and: xtables-config-parser.y:20:28: error: libnftnl/table.h: No such file or ...
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40 views

Amazon VPC one way communication issue [closed]

I have 2 sites. 1 - Amazon China: 10.50.0.0/23 with a few instances and one which is assigned with both a public and a private address (let's call it China-GW). This instance has been installed with ...
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43 views

How to speed up dd-wrt iptables command execution

I have a custom firewall script in dd-wrt router. It has thousands of lines in a user-chain like this: /usr/sbin/iptables -t nat -A XXXX -d 1.2.32.0/19 -j RETURN /usr/sbin/iptables -t nat -A XXXX -d ...
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16 views

iptables tcp over NAT with NFQ

I'm working woth OpenWRT on a router, and would like to catch all traffic over port 1234 with NFQUEUE and set verdict according to packet. I know of snort and surricata, but would like my own ...
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dhclient unicast DHCPREQUEST excessive logs

I am using centos 7 with dhclient 4.2.5: $ uname -a Linux hostname 3.10.0-229.el7.x86_64 #1 SMP Fri Mar 6 11:36:42 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux $ dhclient -V Internet Systems Consortium ...
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Linux - Squid on local machine to control outgoing traffic

I'm trying to setup squid on my computer to control the outgoing traffic from the same computer only. If my understanding is correct, squid runs as user "squid" on on most Linux distributions (mine is ...
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38 views

Iptables MASQUERADE only selected ports

I did port forwarding following this tutorial: http://www.debuntu.org/how-to-redirecting-network-traffic-to-a-new-ip-using-iptables/ iptables -t nat -A PREROUTING -p tcp --dport 1111 -j DNAT ...
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135 views

Limit and limit burst in IPTABLES

For some reason I am not able to understand the concept of limit and limit burst in IPTABLES. Could anyone please help me here ! Thank you!
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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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91 views

How do I forward eth0 to wlan0?

I tried to forward eth0 to wlan0 on my Raspberry Pi B+ using NAT on iptables with the following commands: echo 1 > /proc/sys/net/ipv4/ip_forward iptables -A FORWARD --in-interface eth0 -j ACCEPT ...