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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Exposing an internal IP to the internet on GCP

Be warned, noob question here. I want to play around with GCP AlloyDB. I have created a cluster and it has been assigned an internal IP. This is fine for applications running in the same VPC/ project ...
cmptrwizard's user avatar
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IP forwarding with IPTables for lvs nat mode

I am learning about the L3 loadbalancers and now working on the keepalived NAT mode.The packet flow should be Client ------> L3(lvs DNAT)------> real servers and the return flow should be exact ...
chellathurai's user avatar
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ECS task to VPC endpoint/NAT Gateway routing

we have an ECS task that makes Rest API calls of two types: /path1 and /path2 in a Private subnet. We route the requests to Internet Gateway through a NAT gateway present in a public subnet. Flow: ECS ...
pds's user avatar
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VPN overlapping with network that provides access to internet

I have computer which is connected to Network A with ip range 10.0.0.0/24. This network provides access to internet and that's the only thing I need from Network A. My comporate VPN (Network B) using ...
vbargl's user avatar
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Properly configuring iptables for two layers of port forwarding: external server connected to local server via VPN

I had a minecraft server running on a VPS (Debian 10), but the VPS was too puny to handle it so I wanted to use a beefier local server to run it (Ubuntu 22.04). The VPS is hosting an OpenVPN server, ...
Goigle's user avatar
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NAT port to internal node

We are working with a PLC (phoenix plc next) which connects to a profinet (and profibus) network. Due to lack of tooling and being unable to rewire things to our needs (the PLC is integrated in our ...
bas's user avatar
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Why is my Azure VPN Gateway-NAT rule not working?

I have a very simple scenario, Azure Vnet with a subnets 10.140.1.0/24 (GatewaySubnet, SKU=Gw2 gen1) and 10.140.10.0/24 (VirtualMachineSubnet). Then an OnPrem network with 10.190.0.0/16. I have a ...
user2713516's user avatar
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Redirecting traffic to a bridged ip and port using PF on MacOS

I am trying to redirect localhost traffic on specific port to bridged network ip I am using following echo " rdr pass inet proto tcp from any to any port 9300 -> 192.168.64.29 port 9300 rdr ...
MrPandav's user avatar
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How is CGNAT routed on the client?

When testing a Zscaler POC (from a security perspective), I had a hard time understanding how CGNAT is routed on the client. My main concern (and question) is that the 100.64.x.y route is not in the ...
WoJ's user avatar
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What does exactly break with double NAT?

There are many warnings about double NAT networks. DSL---modem with router-----second router configured by ISP inner network first NAT second NAT What will exactly break ...
Jonas Stein's user avatar
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Debian Redirect Single Port of Outbound Connection

I have a Debian 11 VM on a Windows machine. It has 3 network adapters. One is external (WAN), one internal (LAN) and another private (experimental). I am using the box as a router which in turn uses ...
Architect Jamie's user avatar
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Wireguard forward traffic to host

I'm using Wireguard as docker container on a pi. I'm running a couple other services on the pi that I want to be only accessible over the wireguard connection. The wireguard server created an ...
Mark's user avatar
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iptables loses source address when forwarding to an internal virtual machine (Proxmox)

I have a Proxmox hypervisor. This proxmox is running a VM with HAProxy load balancer. I am now trying to forward to this HAProxy via iptables port 80 and 443. Unfortunately the source address is lost ...
alexohneander's user avatar
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How to use aggressive mode + transport mode + PSK to negotiate SAs with strongswan server in NAT-T environment

I used the transport mode and NAT-T environment to negotiate SAs, and the method to authenticate the peer is PSK. When I use Main Mode, IKE negotiation can be completed normally, the logs of PSK is: ...
freshman.ipsec's user avatar
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can't get iptables to handle more than 1.5 million nat sessions

I am trying to see how many NAT sessions I can handle in a single linux machine using iptables. I am testing it using a large number of udp packets but I can't seem to pass 1.5 million. I set net....
barisdad's user avatar
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How to health check a distributed NAT gateway?

I am using Google Cloud Platform and have manually setup a NAT gateway to peer two networks A and B so that workloads in network A have a default gateway which routes packets into network B. The ...
dippynark's user avatar
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Does NAT leave a trace of the internal source?

I was wondering if there is any trace left of the original source when a packet leaves NAT. Let’s say I do a series of DNS requests from my machine to a public server. I’m behind NAT. Can the server ...
Sam's user avatar
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How to bind an external IP address to a new NetNat network?

On my Hyper-V 2019 server, which is joined to the domain that's hosted on one of its VMs, I'm running on the 192.168.0.0/24 subnet. I'm setting up a demo of a new DC for a customer, so I need it to ...
InteXX's user avatar
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Is it OK, to use iptables SNAT rule with inverted -o parameter?

Would it be OK/reliable, to use just one rule?: iptables -t nat -I POSTROUTING ! -o eth2 -s 192.168.10.0/24 -j SNAT --to PUBLIC_IP_ADDRESS The BGP linux router has 25 ethernet interfaces. This ...
PepeOnAChair's user avatar
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What is UDP Masquerading behavior when forwarding and listening on the same port to the same remote address?

Assuming the following: ||netns2|<-kernel routing-> netnsRoot| <-network routing-> |remote server| netns2 is a network namespace has a client that connects to the UDP server on UDP/5060 ...
Liam Kelly's user avatar
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Iptables Port-forwarding while preserving client IP

TL;DR: How can I get the client ip connecting to a remotely hosted VPS to be the IP that gets forwarded/natted, via iptables, to a game server running at my house? I have a Rust game server that I am ...
AAron's user avatar
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Destination NAT onto the Same Network in AWS using IPTables

In AWS we have 3 instances in the same subnet/VPC. We would like to have the client instance make a DNS request to a second analysis instance, which will then forward the request to a third instance ...
Astron's user avatar
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How to proxy ftp connection between IPV4 server to an IPV6 client and vice versa

We have a gateway solution which connects legacy RADIO's having ftp server running with IPV4 interface to DU's running with IPV4 ftp clients to do file upload and download operations. And currently we ...
Neeraj's user avatar
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Debian with 2 ethernet as VPN relay (route all traffic from eth0 to eth1 VPN)

Background I got 2 Debian VMs, first one is pptp/wireguard server on WAN 10.10.0.1 and second one's eth0 192.168.100.1, eth1 172.16.100.1. Note: WAN IPs written in private ranges Intentionally ...
Shahaboddin's user avatar
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Should I do the stateful matching with iptables for nat table?

I often see that there are some stateful matching rules in a iptables' chain such as INPUT. I known what they are doing, and I'm interested in that Should I do the same for the chains of the table ...
Leon's user avatar
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Why does everybody use MASQUERADE/SNAT instead of NAPT/PAT?

Story I have a VPN wireguard virtual interface wg0 (can be anything else) and a physical interface eth0. I want to route packets from the VPN to my LAN, or from an interface to another interface. ...
None's user avatar
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Two clients behind NAT on a single VPN connection, exting on two separate public IPs

I am looking for a way to forward outgoing traffic on separate IPv4 addresses for different clients connected through the same VPN tunnel, behind NAT. Right now I am forwarding port 44158 from ...
Alex Protopopescu's user avatar
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Iptables hitcount instantly blocks ssh

Need some help with iptables. I always use to have vps with public ipv4 ip and used these rules in iptables to block ssh connections that tried to connect too many times. -A INPUT -p tcp -m tcp --...
xPalis's user avatar
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How to share VPN network access

I have got this setup with two LANs and OpenVPN infra. I need to share the OpenVPN connection attached to Proxmox server (10.8.0.12) to the Proxmox VMs (192.168.0,1,2,3,...). I was trying to use linux ...
Roman's user avatar
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Does AWS Educate allow the creation of NAT gateways?

I am trying to have quick access to the internet from a private subnet. I get this error message when creating a NAT gateway: There was an error creating your NAT gateway You are not authorized to ...
Caterina's user avatar
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2 votes
2 answers
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load balancing over single NIC to overcome per-connection limit

I have a strange setup where the ISP provides a very fast connection (10 Gbps) but limits each connection to 50 Mbps. This is fine for multi-threaded applications where I can just boost the number of ...
mohotmoz's user avatar
2 votes
0 answers
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MetalLB on a host with multiple NIC

I need help with some deeper networking stuff. Hopefully somebody can help me or at least push me to the right direction. At the moment I have a two node bare metal (VPS) kubernetes cluster setup with ...
MattDog's user avatar
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How do I redirect URL while also changing source and destination IP address over HTTPS?

I have a SaaS service which exposes an URL (let's say (https://mylink.foo.com) that is only accessible from some whitelisted IPs. However we now need the aforementioned URL to be accessed by an ...
madprofessor's user avatar
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Would getting an Access Point potentially help fix my NAT? [closed]

Not too long ago we switched internet providers to T-Mobile Home Internet and the speed has been a huge improvement, but recently a problem has risen to my attention of the NAT type on my family's ...
Selonianth's user avatar
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SSH over Mikrotik NAT fails

I have a server on my network which I want to expose to external SSH connections. I can ssh directly to the device from my network (e.g. ssh 192.168.88.162 works fine). I have a NAT rule set up so ...
GKruger's user avatar
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1 answer
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iptables NAT REDIRECT

I have a server that is receiving syslog traffic. Many of my devices can only send to the default udp/514 port. My syslog server can't run on ports <1024 and is running on 5000. I have a nat ...
Dan Massameno's user avatar
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Unable to SSH into my proxmox hypervisor from a VM

to start, here is my infra in summary : I have a Proxmox server with an IP public, I created a vmbr1 bridge from Proxmox (192.168.0.1) and I use IP 192.168.0.108 for my VM. Here is the route : 192.168....
Rémy Bauduin's user avatar
3 votes
3 answers
2k views

GCP - why cloud NAT needs cloud router?

Why GCP Cloud NAT needs BGP/Cloud Router? Cloud Router documentation Cloud Router enables you to dynamically exchange routes between your Virtual Private Cloud (VPC) and on-premises networks by ...
mon's user avatar
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Issue with TFTP and IPTables and (s)-NAT

I've some issues with TFTP download behind NAT using IPtables and i could really use your help. I'm familiar with networking pricipals, but pretty new to IPtables, so i'm sorry if i'm doing something ...
HMH's user avatar
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1 vote
1 answer
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pfSense NAT to server in a second LAN subnet behind an internal second router (not working)

I have a pfSense firewall/router that is exposing some services to my public ip. This is working fine, as long as the service is on the primary LAN subnet (192.168.1.0/24), let's call it LAN-A. E.g. ...
ppenguin's user avatar
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How can I configure Wireguard running in a docker container on a VPS to allow communication between its' connected clients?

I have a VPS running WireGuard as a server in a docker container, where I've given it the devices I intend on adding as peers. I have a home server running WireGuard as a client in a docker container ...
theburntcrumpet's user avatar
1 vote
2 answers
566 views

Flushing IP table doesn’t flush NAT

When I execute sudo iptables -F,my iptable rules for the nat table are not flushed. Why is this the case? What does the above command do? I believe there are three tables: filter, nat, and mangle. I ...
average_coder25's user avatar
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0 answers
591 views

MikroTik - configure NAT behind NAT

I have primary Mikrotik router connected to Internet provider and serving internal network 192.168.88.0/24. I also have second Mikrotik router which I want to plug into my internal network of the ...
ivan.ukr's user avatar
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1 answer
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How to toubleshoot port blocking issue

I'm forwarding port 80 of a web server to the public interface of the firewall, which is then mapped to a domain name so that the server can be accessible from that domain name. I did this process too ...
Menas's user avatar
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1 answer
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FreeBSD: How can I tune the lifetime for TCP/UDP for in kernel NAT?

There used to be these sysctls in older versions of FreeBSD, viz: net.inet.ip.fw.dyn_ack_lifetime=3600 net.inet.ip.fw.dyn_udp_lifetime=15 now on FreeBSD 12 sysctl reports that these don't exist. How ...
pnadeau's user avatar
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how can I NAT a NAT IP

I have a server on AWS with a floating (secondary) IP. During integrations with a partner I provide my secondary IP to be whitelisted and define a POSTROUTING rule to SNAT my IP to the secondary IP ...
DevopsinAfrica's user avatar
12 votes
4 answers
8k views

What happens if two local systems download the same resource on same port?

I'm aware of NAT table. I just want to know what happens if two clients in a private local area network want to download exactly the same resource on the same port? In other words , When a packet ...
S.B's user avatar
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1 vote
2 answers
378 views

Choice of NAT64 prefix

I'm about to deploy NAT64 and I noticed that it's possible to use your own prefix instead of the "well-known prefix". Now I can imagine complex scenarios with multiple NAT64 gateways serving ...
OttoEisen's user avatar
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1 answer
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NAT64 on Debian

Update 2: I wrote a quick&dirty tutorial for Jool on Debian 11, since their website is very thorough, but also slightly confusing and the examples too complex for most cases. I'm looking to go ...
OttoEisen's user avatar
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0 votes
3 answers
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How to prevent netfilter to automatically change the source ports

I observed that netfilter changes the source port when a connection is established in the conntrack module. I need to prevent this behavior. Here is what I have done to reproduce my problem: I create ...
sebastien dontneedtoknowthat's user avatar

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