iptables is the userspace command line program used to configure the Linux 2.4.x and 2.6.x IPv4 packet filtering ruleset. It is targeted towards system administrators. Please, when asking a question about iptables, add the output from the following command: iptables -L -v -n

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iptables forward traffic from specific port to secondary interface

Have a machine1 with 2 interfaces: eth0: 10.123.111.48 eth1: 10.123.111.52 machine2: eth0: 10.123.110.63 eth1: 10.123.110.24 There is a valid route from machine1 eth1 to machine2 eth1 for port 3306, ...
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24 views

Linux forwarding packets to remote destinations (not localy)

Network case: Source--Routers ... eth0=LINUX=eth1 ---- some routers.. -- Destination 2.2.2.2 10.0.0.1 192.168.0.1 1.1.1.1 and 1.1.1.0/24 via ...
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29 views

Need to redirect traffiic from the tap interface at0 crated by airbase-ng to apche2 server runing on my localhost 127.0.0.1:80

My dhcp config file /etc/dhcpd.conf authoritative; default-lease-time 600; max-lease-time 7200; subnet 192.168.1.128 netmask 255.255.255.128{ option subnet-mask 255.255.255.128; option ...
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34 views

Internet from AWS Private Subnet Instance Not Working

I created on AWS a VPC with a private and a public subnet. I launched an instance from the private subnet and I would like to access the internet through the NAT server. Disabled the ...
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20 views

Why iptables is not logging

I have the iptables configuration below. I want to block all input but accept some rules. But I want to be able to log the droped connections. But it's not logging. I have this: iptables -N ...
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29 views

Configure local squid for caching and redsock behind squid proxy parent

I'm using Debian, and to access to the Internet my network follow this diagram: MY PC -> SQUID PROXY (with digest authentication) --> INTERNET To resolve the digest authentication with my ...
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42 views

Xen bridge - block traffic from port range - iptables / ebtables

I use Xen with bridge interface : - eth0 - viifbr0 - Name of VM interface : vifv10XX.0 Do you know if it is possible to block output traffic from source port range for a domU please ? If yes, can ...
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31 views

How to reach a private IP (DHCP enabled) from a public facing IP through NAT?

Lets say we have computers C1 and C2 C2 has two network interfaces C2.eth0(public facing) and C2.eth1 local second physical network (addr:10.10.70.101 and Nw:10.10.70.0) Now, there are multiple ...
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21 views

Multiple ssh port-forward to 1 OpenVPN client which connects to 2 OpenVPN servers

I have the following setup: SSH PortForward + OpenVPN Client/Server config My VPS box at myvps.example.com runs 2 openVPN client sessions to 2 physically separate OpenVPN Servers 1&2. SOCKS ...
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24 views

Why does iptables OUTPUT chain oversee packets?

I am working on a Linux (Vyos, i.e. Debian Squeeze) firewall that has ISC dhcp-relay installed and I am hit by the packet duplication bug discussed in ...
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71 views

“Connection timed out” on Debian jessie after some successful tries

I have a root server hosted at Hetzner. After upgrading the server to debian jessie I experience connectivity problems. After connecting successfully to the server for 2 to 5 times it stops answering ...
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39 views

Iptables REDIRECT rule has no effect

I have a VPS which is accessible via hello.com, running ubuntu and a minimal Python script that serves some html content. The python script is listening on port 8069. hello.com:8069 works as expected, ...
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56 views

Accessing hosts IP from within Docker Container - OVS & IPTables

I followed this article to setup openVSwitch on my coreos hosts so containers can communicate across multiple hosts. I have also setup docker so inter-container communication is disabled by default ...
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21 views

Can potential conflicts arise between IPtables port blocking and NAT port translation?

I have set my iptables rules to open only some ports for outgoing connections. I also have snat iptables rules to do NAT which I presume will do a local IP to public IP and also a port translation, ...
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24 views

Get access to host in OpenVPN network from global network

I need help with next situation. I have OpenVPN server set up on virtual machine in Azure cloud. This server have 104.208.34.118 IP adress. There are client, connected to this server, behind the NAT ...
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36 views

Logging Simultaneous Open Connection Establishment With Iptables

Simultaneous Open Connection Establishment: TCP is also set up to handle the situation where both devices perform an active OPEN instead of one doing a passive OPEN. This may occur if two clients are ...
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27 views

Cant configure NAT in iptables

Есть два сервера с линукс. Первый выполняет роль роутера, он имеет два сетевых интерфейса, один из которых подключен к интернету, другой к локальной сети. Второй сервер подключен к локальной сети. ...
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62 views

CentOs 6 as Firewall, forward traffic from eth1 to eth0 -> destination host prohibited

I'm setting up Firewall with a CentOs 6.0 for testing. I'm doing this on two virtualmachines. First VM (Firewall) has 2 interface: eth0 - connected to NAT with 10.0.2.10, access to internet eth1 - ...
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28 views

Why, on a linux router, clients can still connect even after the network adapter is down or the iptables routing is disabled?

I have a Linux machine which I use as a wireless VPN router. It has a very classic router setup, whose highlights are: openvpn to connect to the VPN, which is connected to eth0, and makes the tun0 ...
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139 views

Tomato router killswitch using iptables

I have a tomato router setup with a VPN service. Everything works fine and I also have it that when the VPN drops it kills the connection so that any device connected to that router would never go ...
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60 views

iptables POSTROUTING DNAT Issue

So I am attempting to do something along these lines but hopefully with a single router instead of two. My network is as follows: Device 1 <--> (Interface A | Interface B) <--> Device 2 ...
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39 views

No response on openSSL connection on client but response from client to some servers

I have a Ubuntu 14 based firewall running IP tables configured through FWBuilder. If I ssh onto the firewall and run openssl s_client -connect 176.34.155.20:443 I get a full set of responses ...
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68 views

How to prevent outgoing UDP flood

I've been googling for hours now but can't find a sure or helpful answer. I need to disable high-volume outgoing UDP from my server. I'm trying to configure APF because of the RAB functionality, but ...
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81 views

How to allow VPN traffic only over shared internet connection on Linux?

I have a CentOS server where I set up Internet connection sharing. eth0 is connected to ISP, eth1 is connected to local network, so local traffic route is eth1 => eth0 => Internet. For ...
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61 views

Failover Forward IP Packets with port from one server to another

Basically none of the solutions online have worked so far. Here's my setup: To simplify things, we're gonna assume it's a VNC server, My setup is a fully integrated OwnCloud and Ulteo. I've ...
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64 views

iptables - forward traffic to VPN client

Following Scenario: Router forwarding traffic on port 80 to Machine A Machine A 192.168.0.254 Running Owncloud on port 80 Connected to VPN Provider Machine B 192.168.0.123 can connect to ...
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53 views

Docker - Service accessible from external IP only

I am having a strange issue with a statsd instance running in a docker container. I can connect to the server from outside the host machine (using its public/external IP address). But I am unable to ...
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38 views

Disable OpenVPN LAN access

I have a Debian VPS running an OpenVPN server with this basic config: http://aaronlevie.blogspot.com/2011/07/openvpn-and-pptp-server-setup.html What I need is to disable the virtual LAN the OpenVPN ...
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37 views

Mysql on a remote sever: iptables - allow access only for the application server

I am migrating my MySQL Database to t new server on Ubuntu 14.04. It is working fine at the moment. I am trying to set up the right iptables for both server (web application server and mysql server). ...
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29 views

iptabels stcp packet not reach nat table

i want to forward sctp packet to my internal network. then i configure forward with -p sctp in nat table. but i found it not work at all. then i add some log to track to see what happen. it's ...
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74 views

Connecting tenants of two OpenStack servers using Openvpn is not working

I have two openstack servers in the same network: OpenStack server 1 having the IP: 192.168.25.9 OpenStack server 2 having the IP: 192.168.25.13 I have a tenant in each OpenStack server and I am ...
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128 views

web server behind NAT cannot be accessed by the same network using NAT router IP or domain

I have 1 host server as NAT server, it has public domain name example.com tied to its public IP address PUB_IP_ADD. I have another web server behind NAT with IP address 192.168.1.100 and port ...
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35 views

iptables redirect and editing with netsed

I'm using iptables to filter traffic, the following works on my server: iptables --append OUTPUT --match string --algo kmp --hex-string '|1f 1f 1f 1f 1f 01|' --jump DROP But I want to instead ...
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35 views

iptables to redirect DNS queries on bridge

Setup: Router -> (eth0)Server(eth1) -> Switch -> devices #/etc/network/interfaces auto lo iface lo inet loopback iface eth0 inet manual iface eth1 inet manual #allow-hotplug br0 auto br0 ...
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50 views

cannot start iptables on opensuse linux

i am trying to run the iptables service on opensuse linux , but unforunately its failing to activate and systemctl status message shows that its failing to find the /etc/iptables.rules file , i also ...
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33 views

Two ips rotating each time an email is sent - iptables

I have two ips attempting to rotate each time an email is sent from server. The following commands say they are configured: sudo ifup venet0:0 ifup: interface venet0:0 already configured sudo ifup ...
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21 views

General matter of stateful iptables

I made a set of stateful iptables rules which only handle accepted traffic (More or less). The workflow can be seen in the image below. My questions are: Is it a good idea to drop INVALID state or ...
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17 views

Is there any reasons not to disallow port scans on a public server?

Port scanners like nmap or angry ip use TCP packets with flags Fin, psh, urg on. Are there any reasons not to block TCP packets with those flags on?
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100 views

openvpn port UDP 53 connectivity issue

I need to run openvpn server on port 53. I have a bind server already running on this port. Here are my iptables rules to let my gateway decide to which service it should redirect traffic: # ...
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56 views

Iptables config for BubbleUpnpServer

SUDDENLY my bubbleupnpserver is not able to connect on the port 58050 for http and 58051 for https. Yesterday was working, no changes on the server, puff, today no working anymore. Maybe it's ...
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44 views

iptables hex string match rule migrate to Vyatta (BROCADE)

I have a string match, drop rule working in iptables firewall that I would like to migrate to a Vyatta firewall. Is string matching even possible in Vyatta? If so how can I replicate the following ...
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230 views

iptables configuration for SSDP discovery

I'd like to configure iptables to allow SSDP discovery. SSDP works by sending a multicast UDP packet to 239.255.255.250 on port 1900, to which each UPnP supporting machine in the local network replies ...
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31 views

Expert iptables Nat - Virtual interface ip address issue

I've been looking information related to this problem several days, I had no luck finding a concrete explanation. Explanation about this issue: With this command I redirect one ip to another ip in ...
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22 views

Loading iptables rules from /etc/init.d/

I decided to load my iptables rules from /etc/init.d/ on my Ubuntu 15 server. Is this good practice? Here is the script I have: #!/bin/sh iptables-restore < /etc/iptables.rules exit 0 By the ...
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36 views

amazon server using RedHat EL 7 on port 3306 so that i can access mysql database remotely

I want to remotely access mysqld on port 3306 but when hen i telnet from public ip address i get a connection time out error. Whats happening here. But within the server telnet is working just fine ...
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0answers
80 views

Cisco Anyconnect + iptables - force all traffic over VPN (and drop all traffic when no VPN connection)

I'm trying to force all traffic over a VPN, and drop every other traffic, just like it was asked and done in this question: iptables - force all traffic over VPN (and drop all traffic when no VPN ...
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32 views

iptables -j MARK in the nat tables

I accidentally (didn't read docs enough) set a '-j MARK' rule in the nat table and it seems to work. All the docs say it only works in the mangle table. Is this something that is supposed to work or ...
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64 views

why iptables SNAT doesn't help to answer ARP on the vlan tagged subnet?

I'm using iptables SNAT to setup a "router" on a linux box, it suppose to do NAT for 2 subnets. one untagged subnet 10.0.10.0/24, the other one is vlan tagged subnet 172.16.0.0/24. both subnet come ...
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508 views

Transparent Proxy Issues w/ HAProxy Centos 7

Having issues following steps to transparent proxy outlined here: Howto transparent proxying and binding with HAProxy and ALOHA Load-Balancer | HAProxy Technologies – Aloha Load Balancer Believe to ...
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132 views

iptables open port to an LXC container with public IP

I've encountered a strange problem I have no idea how to fix. I'm trying to close all ports on my server, and open only the ports I need in the directions I need. Thus, I ended up with: IF=eth0 ...