Questions tagged [nat]

In computer networking, network address translation (NAT) is the process of modifying network address information in datagram (IP) packet headers while in transit across a traffic routing device for the purpose of remapping one IP address space into another.

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How to avoid being behind NAT in Azure Ubuntu VM

I am looking to create an Ubuntu VM in Azure whose IP address is the pubic facing one. The VM should NOT be behind a NAT/Firewall. Is this possible in Azure? If so, how?
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Re-routing DNS queries with iptables properly without resolv.conf

I run a custom DNS service on 127.0.0.1:53 and I dont just want all queries to go through it, I also want only that service to respond back. Which is where the problem arises. My NAT iptables setup: ...
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Alternative solution to SNAT for particular use case

I have the following setup. If I add a SNAT rule in VM I can successfully route PC traffic through VM (instead of sending it to Ethernet directly) means I can connect to internet. The rule is: ...
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Host based firewall in NAT environments

Hi getting straight to the point. I am currently working on the architecture of a Host based firewall. My question/pain point is what happens to these(Host Based Firewalls) when LAN-LAN NAT rules are ...
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Can a server behind a load balancer get responses to its requests? [closed]

Assume there are two servers A, B that are behind a load balancer, for example, they could be two docker containers. If server A makes an HTTP GET request to some-site.com, it is possible that the ...
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Does Windows Server 2016 RRAS support NAT reflection/loopback?

I have a home server running Windows Server 2016 Datacenter acting as the NAT on the network. On the same server I'm using Hyper-V to host various services (game servers, GitLab, Plex, etc). I'm using ...
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Exposing udp server behind NAT using openvpn

I have a server behind nat that requires public access to it, and a VPS with an OpenVPN server on it. The goal is to make it possible to use VPS's IP to access the server behind nat without anything ...
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iptables: employ DROP or REJECT rules in non-'filters' tables, namely the NAT table?

For an iptables(8) firewall that is otherwise "properly locked down" in the filter table, is there any use to employ DROP, REJECT or similar, terminating, "blocking or disabling" rules in non-filters ...
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host unable to connect with self through its public ip

I'm on a home network with 2 machines behind a sagemcom router. One machine is a server (RPI) running ubuntu 1804 the other is a regular PC. I've only got a dynamic public ip address (say 1.2.3.4) I'...
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Does an IPSEC tunnel establish new sessions for traffic?

Background AT&T business fiber is basically rebranded U-Verse home internet. The "modem" (it's actually a router, but lets call it that for simplicity) has a hard limit of about 8K sessions. Even ...
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iptables-like NETMAP with nftables

using nftables, I need to NAT an entire subnet to another one for example: 10.10.10.1 -> 10.200.0.1 10.10.10.2 -> 10.200.0.2 ... 10.10.10.X -> 10.200.0.X nftables docs here shows multiple ...
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Restoring default iptable rules after complete wipeout

I am a complete newbie who just accidentally erased all their desktop's iptable chains and rules and wants to restore them all to the previous default (docker nor bootstraps work now as they cannot ...
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NFTables Masquerade Not Working

I am trying to setup NFTables to forward traffic coming in on a specific UDP port to another server with a different IP address. However, it appears my masquerade rule isn't working. When I send ...
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Latency introduced when reloading HAProxy every 15 seconds

We have a use case in which we need to reload HAP every 15 seconds. For every reload, the latency shoots up to 12ms. Normal latency is 7ms at 32k req/s. Below is what I have tried - On the same host,...
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How do routers select ports for Port NAT?

Suppose my computer (LAN address 192.168.0.10), from its local port 56789, accesses 8.8.8.8 on port 1234. If I understand correctly, the following things will happen: My computer sends a packet with ...
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netselect-apt fails to find mirrors

I run netselect-apt (on Debian 10 (stable)) and it fails to fetch any mirrors: Did not found any valid hosts (you requested 10) netselect was unable to find a mirror, this probably means that you are ...
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Redirect all traffic from IP alias to hyperv virtual machine

I have a Windows server 2016 instance with one nic and two IP aliases. It's possible to route all traffic from one IP to a virtual machine running on hyperv? The virtual machine is running Ubuntu with ...
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NAT with strongswan - howto?

Network Topology I have the following setup where Office 1 and Office 2 have the same IP address range (192.168.0.0/16) and both are using strongSwan running on Ubuntu VM (with two NICs one connected ...
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Howto configure Wireguard on Linux router to route all traffic from LAN to remote wireguard VPN server

I've an Armbian linux on a NanoPi R1 running. It routes all traffic from eth1 (LAN static IP, dnsmasq for DHCP/DNS) to eth0 (WAN dhcp-client) via IPTables NAT/Masquerading. That works fine. A client ...
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Redirecting email traffic using iptables or rinetd isn't working but http traffic is

Initial situation: I had a shared cpanel hosting account (website + email). Let's call it mydomain.com with ip: a.b.c.d The DNS RECORDS were like so: mydomain.com A a.b.c.d mail.mydomain.com A a.b.c....
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Inbound traffic is not working via public IP of server

I have two servers in a private network in our VPC, both have public IPs and private(10.0.0.0/24) subnet. Server 1 is configured to be NAT (ubuntu 18.04) Server 1 has only following configuration and ...
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Requesting help / assistance on NAT VyOS configuration

i would like to request help / assistance on NAT VyOS configuration. i'm new to it, so please bear with me :) please see link for the sample diagram. https://i.ibb.co/kx1N6pD/NAT.png from the ...
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Virtualizor Hetzner IPV6 subnets

I am trying to configure a Virtualizor instance on a Hetzner machine but I can't make it to work since I need to "nat" the IPV6 subnets. I divided my /64 subnet by multiple /80 subnets and I added a ...
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Read a million Q/A on iptables redirection of packets to a local port and answers don't answer to my context

My filter table has a policy of drop. (I absolutely want this, poke holes when needed) I want nat table to intercept packets going to 443 and send them to any other port on the same machine I choose. ...
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Would there be less load on a NAT firewall if some or all of the traffic were routed over IPV6 Instead of IPV4?

Just curious.. I was thinking that, on a NAT firewall that is normally overloaded, offloading some or all of the IPV4 traffic to IPV6 might make a performance difference?
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wishing to allow access to one internet site only via openvpn

we have openvpn at work. it allows connection in and around the network with no issues at all. we've chosen not to push the default gateway so the staff connect use their own gateways to get internet. ...
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Any way to run a VPN server behind a nat that one has no control over?

I have a 4G router in a remote place to connect to the internet. My ISP does not give my router a public IP, instead it seems to put multiple sim cards into some private network behind a NAT (which I ...
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Is there an ipv6 equivalent for net.ipv4.conf.all.route_localnet

Is there an ipv6 equivalent for net.ipv4.conf.all.route_localnet ? (According to nftables ip6 route to localhost/ ipv6 nat to loopback, there isn't). If not, how the use case described in Port ...
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How do you configure access lists to restrict inbound ports while allowing all outbound traffic on a Cisco 2911 router with NAT?

First caveat: I did not design this network. Most of my recent networking experience is with ASAs; configuring NAT & ACLs there is pretty easy and straightforward. In this case, the engineer who ...
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Different source IPs when connecting to AWS instances in same AZ

When connecting to my AWS instances in the same AZ, I am able to connect to some instances and not others even though all instances were using the same NACL an Security Groups. My security groups ...
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Initial one way audio with SIP trunk

I have an Asterisk server sitting on my network behind a pfSense firewall, it has two trunks, one for my household provided by my ISP using PJSIP and the other for my business provided by a third ...
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NAT entire subnet with nftables on linux [duplicate]

In order to manage traffic for an IPSEC VPN connection, I need to NAT an entire subnet with nftables, for example: My subnet: 192.168.1.0/24 My NATed subnet (part of VPN interesting traffic, it's ...
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iptables SNAT and DNAT on same packet inbound

Is it possible to SNAT and DNAT on same packet based on dst ip and port? For eg: 10.0.0.4->10.0.0.5:5000 changed to 192.168.0.1->19.168.0.2:5000 iptables -t mangle -A PREROUTING -p tcp -d 10.0.0.5 ...
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Proxmox NAT issue

I have a proxmox server with 1 public ip that is natted to internal network, on which i have 2 vms: VM 103 - 10.10.10.3 VM 103 - 10.10.10.4 I have also setup some port forwarding from the public ip ...
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Make hard-drive from LAN available for storage on Nextcloud server

I run a nextcloud server on a linux server. I have full root access to this server. this server has a permanent IP address. Unfortunately this server does not have enough storage space. At home I ...
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How to assign a static IP to a VMWare guest with NAT Network Adapter?

I am creating VM Workstation Linux guests with NAT network adapters and I would like some of the images to have static IP addresses. I have read this proposed solution but I am not able to get it to ...
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Strongswan Centos 7 Config Issue

I have a problem with configuring Strongswan on Centos 7 ! First please notice that I want to connect with only username and password and I don't want to import any profiles on my phone ! My server ip ...
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Too long TCP handshake while doing NAT

I've installed Mikrotik hEX at location 'A', Mikrotik hAP AC^2 at location 'B', and connected each with OVPN L2. Both two routers have their NAT features turned on, and have their private network. hEX ...
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User can't connect to Strongswan IKEv2 VPN server Firewall issue

Guys I have installed Strongswan on my ubuntu 16 server with help of this tutorial : https://molchanoff.me/administration/ikev2-vpn-server-with-strongswan-and-lets-encrypt/ But when a user wants to ...
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pfSense - can't connect to server from LAN with DDNS address

I've tried looking for a solution to this, but I'm honestly at a loss for what to search for. I'm using pfSense with a separate LAN and DMZ with several port forwarding rules. I'm hosting a service I ...
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Configuring NAT with Traffic Control for Nginx/Apache on localhost, cache miss

Apache is on 127.0.100.2 and Nginx is on 127.0.100.3, with Traffic Control performing DNAT from the former to the latter (for source 127.0.0.1) and SNAT from the latter to the former (for destination ...
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ipsec strongswan UP but no routes

I have a server (Debian 10) behind a NAT router. In this server are running multiple VMs. I want to establish an IPSec connection to a server on the Internet. Here are my ipsec.conf files on both ...
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Is it possible to deploy NAT64 gateway on shared IP vServer?

Is it possible to setup a NAT64 gateway (e.g. Jool, WrapSix) on a vServer which has a shared IPv4 address (192.100.100.100:20000-20020)* and normal IPv6 address? *The vServer's IPv4 address consists ...
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NAT on Windows10 with 2 NICs and OpenVPN

Due to a recent pandemia, we have to send our staff into home office. What I'm trying is to enable some of them to use their PBX system IP phones from home. This is a quite easy task using a VPN-...
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Iptables SNAT not applied in Multicast routed traffic

I'm trying to setup Source Nat Translation (SNAT) over routed multicast traffic with Iptables and Smcrouted. The fact is that SNAT does not apply in this cases: When traffic is routed for first time....
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How to connect VPN clients through NAT to SQL Server

We have 2 servers, 1 Windows Server 2019 Standard used as a VPN Server, 1 Windows Server 2012 R2 with SQL Server on it. These 2 are connected by an internal network, 10.1.1.0/24 address range, VPN ...
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iptables NAT with multiple internet interfaces

Now I have three network interfaces, eth0, eth1 and eth2. eth0: 45.1.1.1, connect directly to the internet eth1: 192.168.11.1, the gateway before the router eth2: 45.1.1.2, connect directly to the ...
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IP masquerading - map incoming port on interface A to outbound port on interface B

(Edited to simplify the problem) I have a CentOS 8 machine with two interfaces. I would like to take incoming UDP/TCP connections on network interface A on a particular port and forward them to ...
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Dual-way NAT forwarding using IPVS?

I want to replace iptables(8) with IPVS for a TCP reverse proxy which involved dual-way NAT. My current setup using iptables is functionally equivalent to a userspace forwarder (like socat(1)). It ...
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I can't create a NAT Gateway

I have a VNet /16 with 2 subnet /24 (private and public) In my Public subnet, i have a windows with a public IP. I can access this windows with RDP. In my Private subnet, I have a Linux with no ...

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