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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Cisco ASA 5505 - NAT or Port Forward for SIP / VoIP ver 8.4

I just had an NEC PBX installed that lets me use SIP trunks for VoIP services, My gateway is a Cisco ASA 5505 running 8.4 and I only have one public/static IP Addresses. So far, my trunks are ...
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Apache2 server (behind Zyxel USG 100 NAT/Firewall) with vhost does not log real clients ip addresses

SOLVED To allow the Zyxel USG 100's NAT to forward untouched packets to my web server i edited the policy route of the Zyxel. Zyxel -> Configuration -> Network ->Routing -> Policy Route ...
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133 views

Port corruption using iptables NAT on Enterprise Linux 6

I am trying to setup a captive web portal redirect on CentOS using the following configuration: This configuration works for the first few packets, but then suddenly the destination port is corrupted ...
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2k views

libvirt and network filtering with nat - iptables overrides

At first, I want to say: I know, it was done initially wrong and I want to avoid doing everything again from the scratch because of general downtime. I am running libvirt/KVM on RHEL. I've got VM ...
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67 views

IIS and Apache hosting together

I know similar questions have been asked already, but mines a little more unique. I work for an internet/networking company. We build and host websites, as well as provide internet and network setups ...
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608 views

INPUT, OUTPUT or Forward Chain

I'm using a linux box as a router: The Box has 2 public ips and local ip, i'm using natting to allow local users to access the web. When a local user access the web, source natting happens here, ...
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1answer
953 views

iptables and port redirection (nat)

I am trying to build a router from ubuntu 12.04. What I am trying to do is, by using 1 public IP (100.0.0.100) and I tons of local ips like 10.0.0.0/16, to map each port to one ip like; ...
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How to Setup Linux Server As A Router with NAT

We have a simple router which has NAT of symmetric type, but because this router doesn't provide us with any debugging interface, we cannot figure out if a specific packet reaches the NAT or not. ...
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714 views

Accept incoming connection from a second gateway

I searched a lot about the question, but can't find solution for my situation. We've got a Windows 2003 server that runs Advantage Database Server (ADS) through which our site connects to our ...
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2answers
340 views

Redirection with natd flags on FreeBSD

I am trying to setup a basic NAT server. I want all traffic coming from the outside world to the NAT server to be redirected to another machine, where I have a lipcap service running to parse this ...
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461 views

NAT vs Proxy server

I have installed squid proxy server to hide our network ips after some time it becomes slow then I read through NAT rules to achieve what I want by proxy server. As per this link the difference ...
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482 views

Router/Gateway with host-header capability

Can anyone direct me what to look for to get a Router / Gateway / Firewall for my home-office enviroment to be able to run multiple e.g. Webserver on port 80, with one public ip. I know it can be done ...
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352 views

iptables alternative for nat in windows

When setting up a comms server I usually use iptables in linux to forward any incoming connections on a particular port to another server, e.g. Chain PREROUTING (policy ACCEPT) target prot opt ...
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87 views

Multiple routes and gateways with NAT

My setup is a VM host with two network interfaces where I want to use one as private/internal and the other one as public (which will get a public address on the host), where all the NAT magic to the ...
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1answer
1k views

iptables port forwarding to vmware workstation guests on NAT vmnet [closed]

Try as I might, I can't get this to work now for 2 days. Your move, internet. I want iptables to transparently forward (localhost) 192.168.1.40:2222 to 192.168.2.22:22 and I don't want ...
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1answer
157 views

Cisco ASA 5505: Created a faulty NAT rule. Can't reach the ASA

I was trying to create a NAT rule to reach my internal web server from inside the LAN. Something must have gone wrong. Now when i try to reach the ASA through https://192.168.1.1 the response is from ...
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2answers
121 views

IPtables NAT puzzler: Why is traffic from the firewall host being NATed even though it's not coming from one of the prescribed source addresses?

I run a small network where a linux web/mail server also provides NAT for a collection of windows boxes. One of these windows machines is apparently misbehaving (ZeroAccess botnet even though I can't ...
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2answers
392 views

VMWare NAT releasing SYN packets from guest but not admitting SYN/ACK packets to guest

VMWare Server 2.0.2 Host OS is Windows Server 2008 R2 Standard Guest OS is Windows XP I am using VMWare VMNet8, the NAT network. The VM guests can't see out to the network around the VM host. Packet ...
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330 views

Ubuntu Server / IpTables / Port Forwarding / NAT

I got referred here from StackOverflow. I'm using IpTables to forward an incoming port on one server to an external server (not on LAN) and the same port. The problem I'm having is that I have to use ...
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302 views

Keepalived failover not working for Static NAT target behind Cisco ASA

I've got a Cisco ASA[0] with a pair of Linux boxes in the DMZ running Keepalived and HAproxy acting as a load-balancing failover pair for another pair of Windows servers, also in the DMZ. I'm ...
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How to configure and enable NAT with server core installation

Using Microsoft Server 2012 Core: What is the equivalent core/Powershell command to enable and configure NAT. I have configured NAT on servers with the following GUI steps: Server Manager, Tools, ...
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CentOS masqueraded network with iptables clients not connecting: Unable to ping

I'm a novice sysadmin working on a system with a CentOS server masquerading traffic with client machines also running CentOS. Something with the tables got messed up and my clients no longer have ...
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179 views

How to bind traffic of each NAT client to a external IP address?

I have a NAT router with 2 IP addresses, lets say 111.111.111.111 and 222.222.222.222 associated with the interfaces eth0 and eth0:1 respectively. I have two servers that connect to this NAT gateway ...
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1answer
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Dual ISP Inbound NAT — Asymmetric routing

routing question here. In a dual ISP scenario is there way to use both external IPs and nat them to a web server in a higher security level? The issue I am running into is on the return path for ...
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Connect four Modems having same IP with a single Ethernet Switch [closed]

I have a scenario where i have 4 modems connected to a switch. all four modems have IP address 192.168.0.1(default). i want to connect all of these four modems with a single switch in a way that i ...
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How do you NAT Hairpin in IOS 8.3+

As I asked here and duplicated here it appears NAT Hairpinning is the answer I'm looking for to allow internal servers to loopback through the ASA to access external IP's (without using DNS ...
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1answer
995 views

pfsense nat between two internal ip

TL;DR What technology should I use to translate an internal address (192.168.1.10) to another internal address (192.168.1.11)? So that when I access the first I get redirected to the other? Long ...
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96 views

VmWare : listening nat in promiscuous mode

This document describe how NAT in VmWare works. Next picture is from that document. Is there way to configure Virtual Ethernet switch in that way: All packets arrived from nat send to specified ...
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Cisco ASA/PIX Can't Access Internal Resources Behind NAT [duplicate]

My servers are natted 1:1 as follows, i.i.i.i maps to x.x.x.x where i is an internal IP, and x is the external IP. From an i.i.i.i machine, I cannot access x.x.x.x resources... What special ...
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51 views

Zyxell USG200 NAT for local computer using wan address

My WAN public address is linked to the server with NAT. How can I set up the firewall to let all local computer use the same NAT rules for www.mypublicaddress.com address from INSIDE the network? I ...
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1answer
54 views

Lost as to what I'm not doing in setting up a home lan network [closed]

I'm a PC repair tech and this is a problem I've recently been trying to troubleshoot for a customer. Upstairs they have the main router which servers as the gateway and router, both hardwired and ...
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563 views

Windows Server 2012 R2, multiple Hyper-V Virtual Network Switches for multiple VMs

I want to configure something like this: I have one NIC, and have been given 3 IPs by datacenter, on my server which is running WS2012R2, with 10 VMs on hyper-v. Windows Server 2012 R2 (host) one ...
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219 views

Why is an ack response being sent to the wrong gateway?

I was trying to determine why a packet forwarded by iptables to my internal lan is returned on the wrong gateway. Having investigated this further, I determined that, at least in the case of one of ...
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1answer
909 views

NAT rules betweek 2 network interfaces (with iptables)

this is the current network that I have: UBUNTU: eth0: ip: 212.83.10.10 bcast: 212.83.10.10 netmask 255.255.255.255 gateway 62.x.x.x eth1: ip: 192.168.1.1 bcast: ...
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569 views

Understand FTP; Active/Passive with Firewalls and NAT [closed]

I have some basic questions about FTP with firewalls and NAT, I hope someone could help me :) I split them up in different scenarios: Active FTP without NAT Setup: Server 1.2.3.4, Default ports; ...
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1answer
189 views

website not accessible with IIS6 while NAT is configured in Windows 2003

I have Windows2003 server configured with IIS 6. Until now it was working fine, but since I enabled NAT for my users to access the internet via this server, the website becomes unavailable. Note that ...
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61 views

Where can I find the range of IP addresses of my container OpenVZ

I'm looking for the "range of IP addresses of my container"... Where can I find those ? /etc/network/interfaces ? ifconfig ? I don't know and I can't find any answers... I need it for this tutorial ...
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290 views

Variable host IP address in iptables rule

I am running CentOS 6.4 with OpenVZ on my laptop. In order to provide Internet access for the VEs I have to apply the following rule on the laptop: iptables -t nat -A POSTROUTING -j SNAT --to-source ...
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1answer
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iptables forward rule not working in openwrt

I am trying to apply some iptables forwarding rules in openwrt. Here is my scenario - My server has two cards ath0 and br-lan. br-lan is connected to internet and ath0 to private network. The other ...
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1answer
151 views

Adding Multiple Interfaces to EC2 Ubuntu 12.04

I have a m1.medium Ubuntu 12.04 instance with two ENI's. I have a VPC setup with a private and public subnet. Private: 10.50.1.0/24 Public: 10.50.101.0/24 I initiated the instance on the private ...
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Amazon EC2 Nat Instance - goes out but not back in

I've followed Amazon's steps and list what I've done. I've created 6 subnets (4 private SN1: 10.50.1.0/24, SN2: 10.50.2.0/24, SN3: 10.50.3.0/24, SN4: 10.50.4.0/24) and 2 public (SN5: 10.50.101.0/24 ...
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408 views

Socksify TCP connections reaching a gateway IP — preferably without iptables

I have Virtualbox installed on Debian with a few virtual machines. I can't install anything in the guests, and I use host only networking, vboxnet0. The host IP in the host network is 192.168.56.1, ...
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238 views

Cisco ASA, Windows Server 08, PPTP/GRE issues

I am at the end of my rope on this one. I am trying to simply forward pptp/gre through a Cisco ASA to my Windows server. Here is what I have done: Access Rules: OUTSIDE ...
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How do I set a static IP for a virtualbox guest that has a network adapter configured for NAT?

I am running Ubuntu 12.04 as a VirtualBox guest, but I'm having trouble configuring a static IP. I have the network adapter configured for NAT, because I can't assign static IPs on my Universities ...
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40 views

Linux NATing on my own IP address

I have a question regarding Linux NAT-ing on my own IP address. Suppose I have a network interface, say eth0. It is given an IP address of 192.168.0.2. Now I apply a NAT rule in Linux saying that: ...
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Openstack seems to not map internal IPs to local network properly

I have a very confusing issue which I can't seem to resolve. I followed a guide by Loic Dachary on installing Openstack Folsom on Wheezy, and deployed it on two hosts: a cluster node, and my ...
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458 views

How can I access a server on local network using its public name?

I have a problem in which I cannot access a server using its public name from the same network as the server. Access to the server works fine from the internet. Reading up on this problem, I've ran ...
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1answer
402 views

Issue with Nginx, http authentication and dynamic IP address

I am trying to get Nginx as a reverse proxy to authenticate users performing inbound http requests. My ISP provides me with a dynamic IP. I am not sure how to configure my ADSL router (NAT rules). ...
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1answer
207 views

Can I improve speed in Hyper-V?

I use Windows Server 2008 R2 (it is host) with Hyper-V and a guest running Ubuntu 12.04 LTC. It is my settings: RAM 32768 Cores (virtual processes) 4. (I need 12) I also use virtual hard drive ...
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NAT Overloading not working, access-list not catching ips?

I have a GNS3 lab set up and I am trying to get NAT overloading working with a dynamic pool. Please see diagram The issue I am having is traffic is being routed correctly from PC1 to the ISP1 or ...