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 check ip-port mapping after adding a port-forwarding rule by firewall-cmd

In CentOS7, I have made a tcp relay by command "firewall-cmd --add-forward-ports ...". However, now I need to know the mapping rules between incoming ip and the port assigned to the ip by ...
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Outbound Internet Connectivity for VMs on Azure: Virtual Network (with Default Config) vs NAT Gateway

I'm running some VMs on Azure inside of a Virtual Network that I manually configured. For the most part, these VMs just run unattended and if I ever need remote access to them, I just assign a public ...
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NAT+Database Port: Forward local port to remote Server

First, let me pose my immediate question, then I describe the whole context (as the context is a bit involved IMHO). Which IPtables allows me to access a postgres database on "ip.ip.ip.ip:5433&...
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How to ping google (8.8.8.8)

This is my network topology. It is consists of three routers: mikrotik, ciscoCSR1000 and pfsense. Each subnetwork connected to each router is comprised of 2 vlans one for each host. Routers have fixed ...
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Best way to establish and secure communication from multiple subnets to device behind firewall (DMZ, NAT, port forwarding?)

I'm looking for advice on how to best implement a DMZ on a FortiGate firewall (FG-F100), as in the proposed architecture drawing attached diagram. The goal is to establish a security barrier between ...
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redirect (nat?) by subdomain to docker

I have multiple docker applications (Minecraft servers, web servers, databases, unify webkey, etc.) running on a Linux machine. Let's call this machine example.com. Any call to example.com will be ...
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Enable bidirectional UDP communication between Windows host and Docker container

I have a UDP server on a Windows 10 host, on a fixed port (let's say 1234). All I want is to set up a communication between this server and a client in a Docker (Debian-based) container (Docker ...
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How to route traffic from nat interface through GRE Tunnel? - Debian

I have these two dedicated servers, let's call them A and B; I've created a GRE tunnel between the two and it works as supposed to. On server A, I also have a NAT interface configured and it works but ...
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Forwarding all traffic to transparent proxy

I want to redirect all of the traffic from my instance to another instance that’s running a transparent squid proxy, using IP tables rules and NOT changing the instance’s default route. is it done on ...
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Linux iptables DNAT IP range to single IP

I have following rules iptables -t nat -I PREROUTING -d 192.168.0.2 -p tcp --dport 20001:20100 -j DNAT --to-d 169.13.29.133:80 iptables -t nat -I PREROUTING -d 192.168.0.2 -p tcp --dport 20101:20200 -...
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NAT - Two hosts with different private IP addresses but same public IP

I'm studying the NAT-process and I've a doubt about addressing. When the NAT translates the private IP address to a public IP address, it can translate, if properly configurated, different private IP ...
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Use ALB to publish a service using EKS with nodes in private subnet WITHOUT a NAT Gateway

I am using eksctl to provision an EKS cluster in my AWS account. It works fine, but I noticed it creates a NAT Gateway, which is somewhat expensive. Is there a way to have nodes in private subnets ...
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Finding Windows Devices Running Vms on Them With NAT using interfaces

I am tryin to stop domain pcs that are running vms(vmware,hyper-v,virtualbox) with nat configured interfaces. Is there a way to determine it via powershell? I want to find vm's running on domain pcs ...
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How to configure our own Amazon Linux 2 NAT instance

I know there is some tutorial relates to iptables and firewalld, is there anyone who has setup this successfully can give me some consistent command on how to configure the NAT instance on Amazon ...
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IPTable SNAT rule is not evaluated

I am trying to SNAT and DNAT a flow with IPTables and I am struggling with SNAT. The rule does not seem to be evaluated and I don't know why. Here are the rules: Chain PREROUTING (policy ACCEPT 117 ...
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Can't connect to XAMPP using pfSense

good afternoon I have a webServer behind a pfSense and also a static IP address. My efforts are all for trying access my webserver using the static ip address (Access remotely) using a specific port. ...
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route ipv4 to ipv6 as mechanism to overcome not owning an ipv4 block for load balancing purposes on premise k8s (none aws/gcp)

This is not a question about tunnelling, although that may be part of a solution. With public cloud providers it's trivial to request a load balancer due to providers owning large class A/B/C public ...
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firewalld centos 8 masquerade log

I am not able to log NATted packets, I tried to do this with a rich rule which indeed is natting packets. rich rules: rule family="ipv4" source address="192.168.188.0/24" ...
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SNAT/Masquerade not modifying the Source IP occasionally

We do SNAT in our Gateway in the POSTROUTING chain. But we find that once in a while the source IP did not get modified. The packet is going out with the internal IP. We are using IP Tables version - ...
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How 2 dynamic (external) IP devices can talk to each other via 1 static (external) IP [closed]

I have 3 devices: Device 1 (Dynamic IP): A raspberry Pi sending UDP packets to Device 2 via 4G modem via Internet Device 2 (Static IP): My Ubuntu/Windows PC with static IP, successfully receives ...
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How to connect to vpn from the another subnet with the same external IP

I'm working in a building where you rent a room for the office work. We have our server in one of the rooms and other employees in other rooms. The problem is that server needs its own network (don't ...
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Forwarding all HTTP/HTTPS from server to another server

I need to forward all traffic(HTTP/HTTPs) to my server (Digital ocean) to a new server (AWS load balancer) basically the solution is to use nginx as this questions: Forward my http requests from my ip ...
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Resolving Domain Name to Private IP AND Public IP Simultaneously [closed]

Background (Skip if not interested) I have a dev server running in my local network. I can reach it easily by private IP (192.168.2.4). I have my firewall ports open on the server for :80 so I can ...
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PFsense NAT settings for proxy usage

So my PFsense machine is the default gateway of the network. I want all HTTP(S) traffic that is sent to be sent via a Proxy: Polarproxy. Polarproxy declare the following iptable rules for doing so, ...
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WireGuard handshake fails to be received

EDIT: I figured it out, solution below. I've been attempting to set up WireGuard as a VPN gateway manually instead of using wg-quick, as I don't want to route the local machine's traffic over the ...
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Docker to localhost

I am using a framework which sets up multiple docker containers and starts them up. I wanted to update the source code for one of them but do not want to keep rebuilding the docker image. So, I ...
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TCP/IP packet transmission through NAT

Why my TCP packets do not reach the destination? I send http requests from one PC to another PC, both behind NAT: PC1 behind NAT1, runs Wireshark. PC2 behind NAT2, this one sends http requests. To ...
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All traffic on port 5060 gets lost in whole network

I am having issues forwarding port 5060 in my firewall/router to a FreeSWITCH server. Our firewall/router is an Uniquiti Edge Router X. The server's local IP is 10.0.0.216, the router's 10.0.0.1. ...
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Are there STUN implementations that can sometimes handle symmetric NATs?

I've been working on connecting two devices that are each behind a symmetric NAT and managed to make it work quite consistently. However, it takes quite some time for the connection to happen (...
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Can't access VPN server on remote LAN through client subnet

I've got a VPN server running on M1 which is behind a NAT N1. I've got a client M2 which is also behind a NAT N2 (scroll right): M2 (192.168.125.6) -----> N2 (70.23.34.56) --------...---------> ...
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When connecting from one subnet to another through a WireGuard VPN, why TCP requires NAT on both sides but ICMP works without NAT?

I encountered this issue today with the following setup: [Cloud Server] --> [Cloud Gateway Server] <- WireGuard -> [Home Router] <-- [Home Device] I have source NAT on my router. My home ...
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Per-user routing of incoming(!) and outgoing traffic

The outgoing traffic of user1234 on the client should run via the tunnel and be NAT'ed to 2.3.4.5. On the opposite direction a certain port range on that IP should be forwarded back through the tunnel ...
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How does DNS work across two separate networks using NAT?

Apologies for sounding naive in advance, I am a newbie in servers/networking and have a generic question around Load Balancers, DNS and NATting. We have an app deployed on our private data center. The ...
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PPTP & GRE issue iptables/NAT

This is my first post and will try my best to add all the info. I am trying to accomplish something that i am not sure if it is supported, basically I have a firewall that is configure to allow ...
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NAT for a domain name change

We have a customer on a .local domain with a local MSP. We are preparing to migrate the customer to an Azure VM DC and a real domain name. Someone told me that we could use NAT in the on-premise ...
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Terminology: Public IP Server w/Multiple NAT'ed Clients?

I've got a server with a public IP in the cloud that I'm paying good money for. I have multiple computers behind various NATs that I want to talk to each other. (Note: I'm NOT asking about how to go ...
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Use VM as a router for another VM

Hi all I need some VM routing help please. I have two VMs running in VMWare Workstation; Kali Linux (172.16.20.106) & Windows 10 (172.16.20.107). Kali has a bridged (internet) & a host-only ...
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how to config dynamic nat in pfsense firewall?

Sorry for asking you guys something but i'm a newbie in pfsense. So, i'm really not understand how to config dynamic nat (as cisco router) in pfsense? if possible, can you show the step-to-step to ...
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DNAT to another hidden port on same host

I am hoping to use iptables to silently redirect incoming traffic arriving at a privileged port on the public eth interface (public IPv4 address) to a hidden unprivileged port on the same ubuntu box. ...
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Cisco: some NAT and firewall rules do not load after reboot

I am relatively new to Cisco routers but managed to configure most of the stuff successfully. However, there is one problem that I just can't find a solution to. I have set up a VDSL connection on ...
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Can't get Public IP of Inbound Connections from Behind NAT + Reverse Proxies

My network flow looks like this: Public Client ∟--> CDN Reverse Proxy (Cloudflare) - ONLY used for HTTP/S traffic, all else goes direct ∟--> Cloud Server w/ firewalld forwarding ...
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SSH to VM that is connected to VPN through HOST public ip (NAT)

I am facing a similar problem discussed here, but my configuration is a bit different. I have a VPS [host] - with a public ip - running a vm [guest] that connects to a VPN server (out of my control) ...
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Building a VPN that assigns local IP to each device

I am trying to build a VPN, both site-to-site and point-to-site. I need the network to give each device a unique IP (doesn't have to be static) to identify them. Namely, if there are three devices in ...
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iptables and SNAT spoofing

So we are working with iptables at class and I've been testing some rules in the NAT table. As far as I know SNAT changes the IP source of a packet to which the rule dictates but what I tested does ...
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Proxying packets back using iptables

Problem: requests from web-application server to main server should be proxied back to web-application server. So if I perform a request from web-application server to application's domain (or public ...
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Linux: NAT punchback for VPN/SSH services [closed]

I have remote Linux server behind NAT, without ability to forward ports. All outbound ports are open though. I need to be able to connect to OpenVPN & SSH ports on this server from arbitrary PCs / ...
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Iptable rules for SMTP NAT to borrow static public IP of data center server

I'd like to run my own mail server on my (decent) home ISP connection rather than trusting my emails to any data center provider - mostly because I already have a machine running. Although in practice,...
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Can a server with no public IP interface be a NAT?

Dear networking experts I have an Ubuntu 18.04 instance in a cloud (say A), that is assigned a public ip address an can be logged in from internet, however its only network interface is private: 2: ...
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Connections not obeying conntrack

I have a tunnel set up on interface vti68. I am NATing both the source and destination. The host has 10.1.30.51 as local, and 172.16.0.80 as remote. Traffic in the tunnel is translated such that 10....
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Why does setting MTU 1452 solve Internet problems and how to fix root cause?

In our church we get Internet uplink from a friendly neighbor’s WiFi. At first everything seemed (at least) fine but since some weeks general “Internet stability problems” increased and since approx. ...

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