Questions tagged [nat]

In computer networking, Network Address Translation (NAT) is the process of modifying IP address information in IPv4 headers while in transit across a traffic routing device.

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How to use my VPS to redirect traffic to certain port tomy Windows PC which is behind NAT?

I have an Ubuntu VPS which is accessible. Also, I have a local Windows PC which is not, because of NAT. What I want to do, but am struggling with: I want that all traffic to certain port to the VPS ...
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Multi-WAN Routing on Ubuntu DHCP Server

I am not an expert on Linux, however I am trying to achieve something for our small office configuration. I have an Linux machine with Ubuntu 16.04 server installed. The machine has two NIC's on it. ...
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iptables: MultiWAN and portforwarding & port redirection

I'm running Gentoo Linux, so using plain iptbales to manage my firewall and networking. I usually use wan0 for all my traffic, but since I have already a web-server behind that i would like wan1 (bind ...
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Connect to VPN server via VPN client which is a NAT instance

Main question is how to connect to a vpn server via a vpn client which is a NAT instance, let me describe about it. Scenes 1: I have a group of service instance(ubuntu 18.04) named A One instances ...
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Change destination IP of the packet to localhost and redirect it to another port

Following is the requirement First, change locally generated requests/packets destination IP to localhost. For an example 172.17.0.1:7199 -> 127.0.0.1:7199  Then redirect this request/packet to ...
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Ubuntu Server - “Virtual” Network Interface with Internet Access

I have an Ubuntu 18.04 server with one public network interface (eth0). I'm trying to create additional "virtual" network interfaces that will also be able to access the internet with NAT rules set up....
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How to treat packets emited locally equally to those received via network (iptables)?

If a network packet is emitted by a local IP (an IP set to a network interface in the system), it is treated differently to those packets that arrive via the non-locally (i.e. via the network)? An ...
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How to tunnel all traffic through a socks5 proxy (nat)?

I have a device A where it doesn't connect to the internet running at 192.168.1.2 (internal network), and then I have a device B that connects to the internet and has a socks5 proxy running 192.168.1....
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Nat a multicast address between two NICS of a linux box both on different subnets

I am using Linux centOS as a router to NAT traffic between two subnets. I can route/nat unicast packets with no problem using iptables. For simplicity sake lets say I have computer A (192.168.0.1) ...
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Redirect all network traffic except ssh

I have a Linux box (let's call it Network Probe) that i would like to use for network monitoring. I need to redirect ALL the traffic for ALL the protocols coming to ETH0 to another machine (Network ...
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Is there a point to configure SNAT source address in NAT gateway?

Let's say, that one has following network topology: NAT gateway linux-router has a following SNAT rule in place: Chain POSTROUTING (policy ACCEPT) target prot opt source ...
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Networking - VLAN & Router Linux

I have a setup with 1 Debian router + 1 Debian DHCP Server. I need to create multiple VLAN on my DHCP server. From my DHCP server I have internet access. I managed to create and set up my VLANs and ...
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NAT with TUN interface on vm

I'm trying to share a TUN connection from a virtualbox vm with the host machine and the wider local net. I have a android tethering program (easytether) that creates a TUN interface on a debian vm. I ...
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Unable to ping external network from namespace, probably postrouting not working

I'm trying to ping an external ip (in this case google) from inside a network namespace. ip netns add ns1 # Create v-eth1 and v-peer1: v-eth1 is in the host space whereas peer-1 is supposed to be ...
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DS-Lite: Extended NAT binding table

I‘m trying to set up a DS-Lite AFTR. Because of the overlapping addresses of the tunnel connections to the B4s, a normal NAT table does not work (already tried iptables -t nat -A POSTROUTING -j ...
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NAT and complex bridge configurations

I have a complex bridging configuration, which looks like this: There is a default route via 172.31.0.1 dev eth0_bridge. Now I'm trying to set up masquerading between lan_bridge and eth0_bridge so ...
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Problem with bridged mode in VirtualBox

I installed Kali Linux in my Windows 10 in VirtualBox and I use bridge network setting in network settings to give it the same IP address than my home router. But today it is not connecting to ...
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Using WireGuard on Raspberry Pi - NAT issue

I try to run WireGuard with my Raspberry Pi 3B with Pi-OS but the NAT won‘t work. When I start up the WireGuard I got this: root@raspberrypi:/home/pi# wg-quick up wg0 [#] ip link add wg0 type ...
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VirtualBox: How to use a specific interface for NAT?

I have eth0 and wlan0. eth0 is the default interface. What I want is to make VirtualBox use wlan0 as NAT. Is this possible? Host and guest are both Debian. Edit: VBoxManage modifyvm "Debian" --...
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Port forwarding & NAT with nftables

I have an OpenWRT gateway (self-built 19.07, kernel 4.14.156) that sits on a public IP address in front of my private network. I am using nftables (not iptables). I would like to expose a non-...
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Prevent SNAT rules in iptables from being applied to ICMP time exceeded packets?

I have the following rules on a Linux server, to route packets from LAN node 10.0.1.8 (a Windows machine) destined for 192.168.173.93 to 1.2.3.4 and vice versa: iptables -t nat -I PREROUTING -i br0 -...
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NAT: accept a connection and then forward it?

In linux (or BSD), is it possible to accept an incoming connection, read the first payload packet, and then forward the connection to another server based on the contents of that packet? I'm not blind ...
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60 views

KVM: isolation between different NAT networks

I'm trying to setup multiple NAT networks in KVM that are isolated from each other and can't get it work. I face a behaviour that I can't explain, and I would like some clarification about it. If I ...
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nftables rules not blocking traffic

I am testing NFtables and am attempting to set up a basic routing firewall on a linux machine with 2 interfaces, ens37 and ens38. Here is the ifconfig output for these 2 interfaces. ens37: flags=4163&...
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firewall NAT failed while working on nearby equipment; bad cable, both nets up, but packets not passed; troubleshooting advice?

We're FINALLY replacing some older equipment and as a part of that work I pulled two very deep drawers holding equipment farther out than they'd been moved in many years. One of those drawers has a ...
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169 views

How to enable internet access for nixos container with private network

In my host I have: networking.nat.enable = true; networking.nat.internalInterfaces = ["ve-+"]; networking.nat.externalInterface = "wlp2s0f0u8"; In my container I have defined: ...
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IPTables Forwarding and MASQ not working

I am trying to setup Traffic forwarding and NAT for my VM machines.I am having setup in which there are 2 linux OS i.e. Ubuntu and CENTOS and I want that traffic should be forwarded from Ubuntu to ...
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Linux disconnect two subnetworks

I have one router with 3 networkcards (one goes global and two are intern) and I would like to know if i enabled in the router nat.ipv4.ip_forward = 1 so does a host on subnet 1 cann reach a host on ...
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Getting access to remote machines through remote server behind the NAT

I want to have access to remote machines that connected to remote server behind the nat (actually it's just another computer with linux). Here you can see scheme. I'm using logmein hamachi to create ...
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410 views

ping to IP address works but ping to domain name not working

EDIT: I have 2 machine setup, Machine A only has internet connection, Machine B ens192 interface connects directly with Machine A interface ens192. So configured iptables in MachineA to make sure ...
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Masquerading does not work in Qubes OS

What I've tried: Arch Linux wiki page on internet sharing (used iptables) Tried using NetworkManager (by going to wired connection, and setting method to 'Shared to other computers') What I'm trying ...
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networking - No NAT when connected via Ethernet

I'm having an issue on my MacBook Air getting NAT to work when connected via USB-to-Ethernet-Adapter, when I'm connected via WiFi everything works like expected. If I ping something external (like ...
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Re-route traffic to an alternative outbound IP address

I have an application running on Alpine that makes requests to a particular IP address/port, say 127.1.1.1:10000. I'm unable to change that particular IP address/port. The service that it is trying to ...
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225 views

How to share an IPv6 connection to the whole LAN?

My ISP still doesn't support IPv6, and I currently use OpenVpn or OpenConnect VPN to get IPv6 connection. Now that there is a Ubuntu server running VPN client UNDER an OpenWRT router. Is it possible ...
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518 views

KVM, qemu, libvirt no internet connection (or dhcp) on NAT

I have configured (using virt-manager) a NAT network with dhcp as follows: <network> <name>default</name> <uuid>dbbdc0dd-20d8-41df-aadb-d8a106170c2b</uuid> <...
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iptables, NAT question

What is the iptables command to achieve the following rule as reported by sudo iptables -t nat -L -n -v Chain POSTROUTING (policy ACCEPT 133 packets, 10675 bytes) pkts bytes target prot opt in ...
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Is there any GUI orchestration available to configure iptables on linux servers?

Is there any open source UI orchestration available to configure IPtables? I have checked in the internet and found some open source firewall packages available but i need a tool which can allow us ...
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154 views

How to fool the bridge to redirect packages of a IP not owned by any interface

I want to redirect the traffic between interfaces over a virtual bridge, when a specific match of IP and port pass through. For instance, when I connect to 10.20.30.40 on port 2222 inside a guest ...
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Difference between FORWARD and FORWARD_direct chain in filter table?

I needed to give ssh access to one of my virtual machines from internet. I added a NAT rule to my firewalld table but it does not work. firewall-cmd --add-rich-rule 'rule family="ipv4" destination ...
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Connect local IP camera to cloud VPS via Openvpn tunnel using DNAT and SNAT

I'm running two IP cameras on my local network with RTSP turned on. I have zoneminder (camera recorder) hosted on my local network and camera streaming directly to it using RTSP. However, I need to ...
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692 views

nat configuration for qemu-kvm guest and host networks

Under an Ubuntu 18.04 host, I have set-up an Ubuntu 10.04 guest VM from a cloned HD. The VM fires up fine, I can ssh into it from the host, but it fails to communicate outside of the host. My ...
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86 views

Synology NAS insmod unknown symbol

I'm trying to follow this guide to setup NAT on my Synology NAS. It worked great for me! I had everything working perfectly. But when I came back the next morning, the NAS had done a system update [...
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OpenVZ not receiving static IP

I have Debian 9 with OpenVZ 6 running on it, I created my VPS like this: vzctl create 10 -- ostemplate debian-8.0-x86_64-minimal vzctl set 10 --ipadd 192.168.1.5 --save However when I start the ...
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Firewall Blocking NATed Traffic Suddenly after adding a NIC

I have home a server that used to have one NIC, but I added a second one to give a dedicated link to the TV tuner. I went from having eth0 (the onboard NIC) to enp7s0 (the new NIC) and enp9s1 (the ...
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How to apply iptables nat rules on reply packets only?

I know the following about iptables nat chains. PREROUTING chain are applied for packets that have just arrived on an interface. POSTROUTING chain works on those packets leaving an interface. OUTPUT ...
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Implementing NAT Hairpin/Loopback for tcp hole punching

I try to test a python hole punching packet based on this article: https://bford.info/pub/net/p2pnat/ The hole punching process worked in several network setups, only the final use case (3.5 Peers ...
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Change default interface docker container

I'm struggling with this problem for two days. Assumptions: Docker network (and interface) named docknet type bridge subnet 172.18.0.0/16 Two interfaces eth0 (192.168.1.1) and eth1 (192.168.2.1) ...
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Trying to setup port redirection through 2nd gateway

I am trying to setup configuration where all connections to port 161 will go through another gateway (through openvpn) while others are going directly [localhost] -> [gateway] -> [remote] - OK [...
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How can I make a service running in Guest VM in VirtualBox accessible outside the VM

I use Oracle VirtualBox and have a service that runs on a guest VM. If I'm under guest OS and open the service URL in Firefox the app works as expected: https://localhost:8443 I was told that I can ...
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104 views

Multiplex multiple services on same port discriminating by source port

imagine that on the same host I have 2 services: an ssh daemon listening on port 22 a socks5 proxy listening on port 1080 I want to multiplex both services using only port 22 but depending on the ...

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