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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Can't resolve domain hosted on same server [migrated]

I have a dedicated server running Proxmox and a VM inside Proxmox running Debian 7. As I only have one IP, I'm using iptables to forward ports to the VM. The iptable rule looks like so: -A ...
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iptables default rules understanding

What does the last part in the following rules means in term of traffic that is allowed in (dtp:domain, bootps) ? From my research I understand that bootps is bootstrap and dpt is destination port but ...
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11 views

IPTables and SIP Proxy-Authorization Header

Is it possible for iptables to check SIP packets for Proxy-Authorization headers, and if there's more than one header in a SIP packet, modify the packet so only the latest Proxy-Authorization header ...
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17 views

port forward from host to libvirt guest virtual machine that is bridged to the host nic

I am having no luck getting access from the outside to a http server running on my network in a Debian virtual machine that was created through libvirt. This what my network looks like: PC1: running ...
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18 views

Forwarding some ports and websites from “eth0” to “wlan0” with IPTables

I have eth0 and wlan0 devices in my work laptop. eth0 access the company's network and it comes with the whole firewall rules and so on. So I’m unable to use Skype, Google Hangouts and other things I ...
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15 views

Set up port forwarding on Ubuntu with ufw

I want to route HTTP traffic from port 80 to port 8080. I added the following rule to /etc/ufw/before.rules -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080 But it works only if direct ...
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37 views

iptables - How to mirror all ports from one IP to a single port on another IP

I would like to set up IP tables on my router to mirror traffic on all ports from 192.168.1.30 and send it to 192.168.1.10:5860 I think I need to combine the two commands below, but I'm at a loss. ...
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30 views

DDWRT - Virtual Interface - firewall command - RDP

I have DD-WWRT flashed on my Linksys e2500v3 router. I added virtual interface to create a guest wifi network that would have access to the internet, but not to the private network or router. At ...
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21 views

How to allow google-analytics via iptables when internet is blocked for other traffic

How to allow google-analytics via iptables when internet is blocked for other traffic? I am running the following script on a wifi gateway. The WAN side of the gateway has ppp0 interface while LAN ...
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15 views

How to see who's blocking my internet connection? fail2ban?

I was just running apt-get dist-upgrade from a distant ssh console when I lost the connection. I would like to know which service blocked my connection. I know fail2ban is sometime a bit flaky, but ...
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22 views

Why CSF blocking all traffic?

I've installed CSF firewall with Directadmin. when the firewall is running, it blocks all the incoming and outgoing connections. My iptables -L -n: Chain INPUT (policy DROP) target prot opt ...
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40 views

Unable to Telnet to the Linux SUSE from windows with port 50000

Firewall has been disable at Linux SUSE server, port numbers from 50000:60020 has been enabled. I can able to ping the server able to telnet using IP. When I give port 50000 or 60000 in my telnet ...
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22 views

iptables TCP flags

I'm beginner with iptables and networking so please excuse me for such dump questions. I found in Internet part of filtering malformed packets: /usr/bin/sudo /sbin/iptables -A tcpchk -p tcp ...
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27 views

iptables TCP flags

I'm beginner with iptables and networking so please excuse me for such beginner questions. I found on the Internet part of filtering malformed packets: /usr/bin/sudo /sbin/iptables -A tcpchk -p tcp ...
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41 views

Windows firewall rule order?

I'm trying to setup Windows Firewall to allow all traffic except a large list of IP ranges connecting to/from a specific application. For testing, I set up two rules: Allow all traffic (no ...
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19 views

+Merlin FW / Port Forward via IPtables?

I have 2 WiFi Thermostats, Heatmiser, that i can control remotely, from LAN without issues, but only one from WAN. The thermo have a fixed port that cannot be changed and there is an App thet can be ...
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22 views

rsyslog loses messages from firewall

I am trying to make rsyslog to log messages from iptables MASQUERADE. I have iptables LOG rule in nat table and PREROUTING chain before the MASQUERADE rules. The actual iptables rules: iptables -t ...
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1answer
25 views

MaraDNS- Unable to forward DNS queries

I tried forwarding DNS queries to Google DNS but it is not working. Below is the content of my /etc/mararc file: csv2 = {} csv2["example.net."] = "db.example.net" csv2["google.com."] = ...
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1answer
20 views

Cannot access DNS from external network

I have setup a MaraDNS instance on CentOS 6.5. I can access the DNS records from local machine—on which MaraDNS is installed—by doing nslookup but cannot access the DNS server records from Internet on ...
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41 views

Configuring iptables for guest WLAN in DD-WRT

I'm constantly failing to get a guest WLAN in DD-WRT working. I can connect to the second SSID and get an IP address of the second DHCP server range. But I cannot connect to the internet. I followed ...
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96 views

How can I route all client Internet traffic through an OpenVPN TAP bridge with Tomato?

I've inherited a Linksys WRT54G router and I'm looking to use either Tomato or DD-WRT to set it up as an OpenVPN client to my home network in Chicago, forwarding all traffic through the VPN link so I ...
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23 views

Route Specific URL to another interface on Linux

I have a Raspberry Pi Model B running Raspian. RPi is in between of my local network and Internet Router (as gateway; so all traffic is passing from RPi's eth0 interface to virtual interface eth1). I ...
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12 views

Determining whether a port is closed (no one is listening) or iptables reject my host

Can I tell whether the service I'm calling has a reject rule in its iptables or it doesn't listen on the port I'm calling? it seems that I always get icmp port unreachable
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22 views

iptables - Cannot redirect with 443 (Https) port

I'm using this command to redirect all web traffic (http and https) to my local server iptables -t nat -I PREROUTING -p tcp --match multiport --dports 80,443 -j DNAT --to 192.168.11.100 But when i ...
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26 views

Using ppp0 via VPN for everything but ftp

I have an ubuntu server I use to wget certain files from the internet via a VPN. I have set the VPN up using PPP0 and currently adjust the route like this: sudo route add default ppp0 Everything ...
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13 views

iptables - How to remove connection tracking

I'm using this command for redirect all web traffic (http) into my local web server iptables -t nat -I PREROUTING -p tcp --dport 80 -j DNAT --to 192.168.11.100 Then i test, access a website and got ...
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21 views

Log and drop packets with iptables

I am using these two alternatives to log packages dropped with iptables: -A INPUT -p tcp --dport 21 -j LOGNDROP # We do not have FTP # The LOGNDROP chain: log messages (rate-limited) and drop all ...
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1answer
89 views

SSH reverse tunnel into Docker container

I need to xdebug something that fails on the server in a docker container and from my laptop I have ran ssh -R 9000:localhost:9000 server and verified the tunnel by telnet localhost 9000. So far so ...
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1answer
36 views

iptables failed with “ iptables v1.4.21: Couldn't load match `-d':No such file or directory” message

I am running kernel 3.14.18 and using iptables 1.4.21, built with these options --static-enable --disable-shared. When I run this command: /sbin/iptables -A PREROUTING -m -d 127.3.0.2/24 -j DNAT ...
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2answers
20 views

How configure requests from other ports to port 443?

I am trying to configure my first https, and i think i get it, but there is a problem: the site wont open in http, just https, because of this, i want redirect everything to https. I am using ...
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56 views

How to allow only subnet for port with iptables

What i am trying to do is to DROP any packets to specific UDP port, except those one from my secured subnet 10.8.0.0/24. iptables -t nat -A --src 10.8.0.0/24 -p udp --destination-port 63210 -j ACCEPT ...
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7 views

How can I see the currently installed netfilter hooks?

Not just the iptables, is it possible to see the currently installed netfilter hooks in Linux PC? Such as the home-made kernel modules that installs netfilter hooks for someone's own filtering rule?
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49 views

Open ports with iptables — still closed

I'm trying to open some ports for a gameserver, which is running on my Linux vServer (Ubuntu 14.04 LTS 64bit). The game needs the following ports: 16261 (UDP) 16262 (TCP) // Player 1 16263 (TCP) // ...
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25 views

Connectivity from different network segment

I have 3 machines 10.10.3.1 Windows # srv1 10.10.3.2 Lubuntu # srv2 10.10.200.1 Windows #cli1 network masks are 255.255.255.240 I can succesfully ping from cli1 to srv1 srv1 to srv2 srv2 to ...
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72 views

Connecting to mysql server at 127.0.0.1:3307 with iptables port redirect

I have a ruby application which, for various reasons, connects to a mysql server running at 127.0.0.1:3307. This works perfectly on the server side, but now I want to run this application on my ...
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21 views

IPTables NAT to webserver how to forward real remote IP

I have a simple setup where I host a webserver in my local LAN 172.16.0.0/27, port 80. It is connected to my DD-WRT router that has a publich IP (direct Internet connection), let's say 1.2.3.4. I set ...
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2answers
110 views

How to use iptables to allow traffic only throug ONE SPECIFIC VPN

I'm trying to allow all traffic from my Banana PI running Lubuntu to only go to my LAN or otherwise through an VPN Server. I'm following this guide: ...
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16 views

Iptables Port Forwarding To Different IPs Based on Port [duplicate]

On a CentOS 6 server with an IP address of 172.16.1.10, how can I configure iptables to route traffic destined for 172.16.1.10:80 to 192.168.1.10:80, and traffic destined for 172.16.1.10:8080 to ...
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1answer
93 views

DD-WRT Wifidog - Redirect isn't working

I have flashed a ASUS AC-RT56U router with DD-WRT version V24-preSP 2201412-22-2014-r25697. Now I want to make it into a hotspot with wifidog TO PLACE IN A SMALL BUSINESS (FITNESS CENTRE) I have ...
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1answer
46 views

How to redirect TCP traffic from one virtual machine to another in Linux?

What is the simplest way to redirect all TCP traffic from one virtual machine to another in Ubuntu Linux and reverse? And what type of connection I suppose to use in VirtualBox?
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89 views

How to split traffic between vpn and ISP

I have vps with configured open VPN server and my router with openWRT and openVPN client. In this moment I can route all my traffic via vpn or ISP. But I want route some connections (for example on ...
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1answer
54 views

Routing 6to4 packets through NAT

I have a linux router(dd-wrt w/o ipv6 module, no space for that) and a linux PC(Arch linux). I'm trying to setup my router to forward 6to4 packets(protocol 41) to my PC and setup the tunnel on it. ...
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39 views

iptables drop packets by IP protocol type

Is it possible to have iptables rules to drop packets by IP protocol type as described in [http://www.tutorialspoint.com/ipv4/ipv4_packet_structure.htm]? (ICMP is 1, TCP is 6 and UDP is 17, but what ...
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64 views

Redirect traffic destined for IP and port

I have a program that wants to connect to 1.2.3.4 on port 5678, but it can't because the port is blocked on our network. However, I do have an SSH tunnel set up that redirects localhost:5678 to ...
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1answer
55 views

Using iptables to allow LAN and drop WAN of unknown devices

I posted this over on stackoverflow but it was off-topic. I have looked around and couldn't find the answer to my question. I am using a raspberry pi as an internet gateway between my LAN and two ...
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42 views

How to configure iptables to set public IP for outgoing traffic from private IP

I have multiple public IPs at home: 1.1.1.1 (main IP) 2.2.2.2 (additional IP) In my local network, I have two computers, let's say 192.168.1.1 (PC1) 192.168.1.2 (PC2) Infront of the computers I ...
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1answer
51 views

slow internet access when routing via a server (both using iptables NAT and ssh tunnelling)

I have a spare computer powered by a dual core intel atom N550 CPU and 2GB RAM (I will refer this as "the server"). It is running lubuntu 14.10 x86 (32 bit) with lightdm service disabled (hence, no ...
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1answer
19 views

How do you force linux to treat a tcp packet as if it were at the destination ip?

The situation: A tcp packet arrives on eth0 with destination 8.8.8.8. This packet meets some criteria that makes me want to intercept it (lets say I am interested in all packets from source ...
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83 views

VPN does not reconnect (cannot resolve host address)

maybe someone can help me: At the moment i am trying to configure a fail-safe VPN connection to a commercial VPN provider on a virtual machine. This is working fine, until my router wants to reset my ...
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65 views

DDWRT - OpenVPN connects, but can't communicate

This seems to be a popular topic, but I can't find any solution to the same problem I am having. Here's the setup: I have a DD-WRT router (build 14896) on a linksys WRT54GL. I have one file server ...