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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routing behaviour (PAT/NAT)

|(eth0: 84.23.13.43) +--------------+ | | | NAT router | ...
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Setting up VMWare ESXi 5 with a single physical NIC

I have a cheap but powerful dedicated server I am leasing with OVH, because they were recently having a promotion. I would like to try and manage all this power by playing with VMs using ESXi. ...
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81 views

EC2 VPC without NAT?

Is it possible to have an EC2 VPC with a public subnet and a private subnet, but without having to have a NAT box? The servers on the private network would not need to talk to the outside world, just ...
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1answer
535 views

Sharing an internet connection from a virtual Windows 2012 AD Server

I have a virtual HyperV network used by a number of virtual development and testing servers and an all-in-one Domain, DNS, DHCP server; I want to keep the many virtual servers separated from our main ...
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2answers
470 views

Symmetric NAT and UDP Hole Punching

I've read this question, but the explanation of Symmetric NAT wasn't detailed enough. Please could someone help me to understand the following paragraphs? I read this about Symmetric NAT: Each ...
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85 views

Routing static IPs

This is probably a simple question for you experts. I have a BT infinity business broadband account, that offers 5 static IP addresses. I'm trying to expose a server on one of those addresses. This ...
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1answer
346 views

How to NAT behind public IP on pFsense before IPSEC to Cisco ASA?

I have two networks: Local 192.168.1.0/24 and Remote 10.8.8.8/24. On the local network I have installed pFsense as gateway. On the remote network there is a Cisco ASA that I don't have control over. ...
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2answers
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How to persist iptables configuration on Amazon EC2 VPC NAT Ami? [duplicate]

I have a small script like this to configure the iptables: #!/bin/bash PRE_STR="iptables -t nat -A PREROUTING -p tcp -j DNAT" FOR_STR="iptables -A FORWARD -p tcp -j ACCEPT" ...
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2answers
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NAT UDP port switching? [closed]

I've read about the Quake 3 networking code that they had to deal with a situation where some older NATs would randomly switch client ports. How common is this issue these days? Is it worth handling ...
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362 views

IPTables: NAT multiple IPs to one public IP

I'm looking for a way how to nat 2 or more inner IPs (in my case xen doms) to one outer IP. I tried to use iptables -t nat -A PREROUTING -d 123.123.123.123 -j DNAT --to 1.2.3.4 --to 1.2.3.7 ...
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1answer
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Route traffic directly between nodes in a cluster

I apologize if this is a really dumb question. Objective Ensure that traffic that is meant to go between nodes in a cluster does not (inefficiently) go outside the cluster and then come back in, but ...
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100 views

Using Linux just for doing QOS on an existing network

I have a proprietary web filtering device which also functions as a NAT router. It's one interface has a public IP and another interface has a private IP. All local clients connect to the interface ...
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330 views

1:1 NAT and ARP issue iptables

Gateway machine with 2 NIC one connecting public network and one for private network. Gateway: eth0 4.x.x.3 Eth1:10.10.11.3 There are 5 Machines with this as gateway all with ip 10.10.11.5---9 ...
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392 views

Single Public IP for Multiple VPN Users?

I'd like to ask if I'm looking in the right direction. We have: 1 x VPN server (Windows SBS 2003) 5 x VPN users (One Public IP) Currently, from our remote office, only one user at a time is able ...
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3answers
933 views

Forward traffic to local LAN IP while keeping the originator IP

I am trying to forward traffic from one server to another, while keeping the origin requestor IP. Therefor I cannot use SNAT or MASQUERADE. SERVER A: Public IP: 111.111.111.111 Private IP: 10.0.0.1 ...
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Martian Source & Servers losing network

First off, I am pretty new at diagnosing network issues through linux. I have an intermittent problem with our LAN servers. They seem to lose all connection to the network and if I disable the adapter ...
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117 views

NAT one network to another using iptables

Trying to NAT ips in different network using iptables. KVM host with ip 10.10.11.36 on bridge br0. Two vms are running with ip 192.168.11.60 and 192.168.11.57 sharing bridge br0. Want to NAT all ...
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1answer
43 views

VPN into private network? [closed]

I am trying to access a network in our office to allow access to a local server, this server is able to send out but is unable to be reached outside of the office network. Would it be possible to ...
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104 views

Get IP of the “requestor” when doing iptables NAT

I am doing NAT traffic forwarding using iptables (1.1.1.1 => 2.2.2.2) with the following commands: iptables -t nat -A PREROUTING -d 1.1.1.1 -j DNAT --to-destination 2.2.2.2 iptables -t nat -A ...
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721 views

Is there any way to filter packets (eg. by iptables) after routing is complete?

I want to drop certain packet destined to an ip_address AFTER it has reached the POSTROUTING chain. However, for iptables, the "nat" table cannot be used for filtering so the following doesn't work: ...
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2answers
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How do I forward/NAT all traffic to one interface/IP to a remote IP?

I have one "server A" that has multiple IPs attached to it, like so: eth0:0 1.1.1.1 eth0:1 1.1.1.2 eth0:2 1.1.1.3 I have another "server B" that also has multiple IPs attached to it, like so: ...
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Access virtual box on remote server

I have a remote server (ubuntu) with 1 public IP. I've installed headless VirtualBox and deployed machine. For now I can access it by VirtualBox's VRDE Server running on server, but what i need is ...
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125 views

RRAS NAT Monitoring

I was wondering if I could monitor my RRAS (VPN) users TCP connection.I don't want to sniff data, however I need to log TCP port numbers and timestamps as well as corresponding users and local ...
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Exposing multiple servers behind NAT using a single public IP address

This is a Canonical Question about NAT and DNS I'm currently trying to set up a network with a DMZ containing a web server and an e-mail server separated from the Internet by a network address ...
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1answer
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iptables NAT Forward 443 Port DNAT,SNAT failing

I'm trying to setup a proxy server that handles http and forwards https to the webserver. Client > Proxy > httpd I added the rules: iptables -t nat -I PREROUTING -i eth1 -p tcp -m tcp --dport ...
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3answers
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Make CentOS 6.x a port forwarding NAT device

I would like to make CentOS a port forwarding NAT machine using iptables. This is the first time I've tried this and I think i might need a little help. This is the configuration i'm trying to ...
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1answer
3k views

Routing traffic through IPSec with NAT and IP Alias in pfSense

I have a pfSense firewall and I need to connect to a remote site (form my client). I'm running into several issues, and don't see traffic flowing in any way. Here's my setup: LAN is 192.168.0.0/16 ...
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80 views

Natting / Port forwarding in cisco FWSM

I have requirement to PAT two different public IP [same port] to single load balancer local IP [VIP] in different ports using a Cisco FWSM. Ex: static(LB,outside) 10.0.0.1 www 192.168.100.1 8282 ...
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65 views

Linux iptables NAT

So I need to setup a server that servers a NAT server for IPMI network xxx.xxx.xxx.xxx = external IP(internet IP) aaa.aaa.aaa.aaa = internal IP A bbb.bbb.bbb.bbb = internal IP B User 1 -> ...
2
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2answers
65 views

Cisco Network Object NAT to get Internet?

So I've inherited a Cisco ASA 5505, and I have no experience whatsoever with the things! There are two Network Interfaces both WAN facing, and the LAN interface of course. Now in NAT rules, there are ...
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498 views

Cisco 1921 - Using NAT (NVI method) between VRF's slow performance

I'm setting up a Cisco 1921 with two VRF's: one to the internet and one to the LAN. The LAN is in private address space so source address translation needs to happen when the packets leave the ...
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762 views

Cisco ASA-5505 Port Forwarding

I have a Cisco ASA-5505 firewall, which is currently configured to share our internet connection and do NAT for my LAN, as well as forward port 443 to an internal machine. I need to forward port 2222 ...
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1answer
787 views

ASA 5510 8.4 Nat & Portforwarding

So I'm trying to forward an internal service on a internal server to the external interface on the same port on the outside interface of our ASA. I been searching for a solution for days and found ...
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1answer
926 views

How to set mark on packet when forwarding it in nat prerouting table?

I have a few port forward rules like this iptables -t nat -A PREROUTING -p tcp --dport 46000 -j DNAT --to-destination 172.16.8.2:46000 iptables -A FORWARD -p tcp -d 172.16.8.2 --dport 46000 -j ACCEPT ...
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Why NATted packets have different source ip addresses?

I've got ubuntu box with nat. Here is the problem: root@office.redhelper.ru:~# tcpdump -i tap0 host 194.190.8.141 -n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode ...
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2answers
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How do I route a public IP range over an IPSEC VPN?

So, I have an established IPSec Site to Site tunnel. Site A has a SonicWall, Site B has a EdgeRouter. The first tunnel consists of Site A's NATed ips to Site B's NATed ips. Everything works as ...
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1answer
177 views

ipsec (openswan) routing or dns issue with iphone

I got an established VPN connection, but either the routing or the resolving is not working. The configuration is taken from ...
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1answer
167 views

Configuring routing for network faults simulator

I'm trying to configure routing on my test machine to pass all traffic via the network errors simulator (WANem). WANem runs in a virtual machine, in the same network with internet gateway. It has NAT ...
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2answers
357 views

limit ip Masquerade to certain ip range

I'm using the entire 10.0.0.0/8 subnet on the private side. I want to allow a certain section of the subnet (say 10.0.0.2 - 10.0.31.254) to access the internet via linux router but not the rest of ...
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1answer
331 views

Running iptables NAT prerouting on second eth interface with different subnet

The situation: I need clients to be able to hit an HTTP server running on eth1 interface on a Linux box on port 8080. I don't want the clients to have to do anything special and I don't want to give ...
4
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2answers
1k views

NAT routing and port forwarding on Cisco ASA 5505

I have inherited my first Cisco router and am having trouble understanding how to do NAT port forwarding correctly. ASA: 8.0.2 ASDM: 6.1(1) I have a single external ip address on the outside (via ...
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2answers
176 views

Configure VirtualBox webserver to see visitors IP address

I finally managed to move my server to VirtualBox virtual machine. VM is running in NAT mode. I have forwarded necessary ports, including the port 80 which I first fowarded with iptables to port ...
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1answer
155 views

How to redirect a packet to localhost in pf?

I am trying to redirect packets that are going to internal network to localhost of firewall. I wrote this rule but it doesn't work. int_net = "{10.0.0.0/24}" ext_if = "{igb0}" int_if = "{igb1}" rdr ...
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0answers
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OpenStack Server Instances have internet access, but they are unable to access the internal network

I'm running an OpenStack Grizzly release with a Nova-Network configuration. [No Quantium]. My network is setup as follows: OpenStack Box (10.10.13.xx network)->OpenStack Internal Network ...
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340 views

Can you configure SNAT with multiple source IP's and use static DNAT (port forwarding)?

We have a private LAN connected to a firewall with multiple public IP's to use for SNAT in order not to overload the ports on a single IP. However, we have a requirement to allow certain workstations ...
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3answers
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Set static IP to a server behind the NAT [closed]

In my company, we just bought a server and now we want to set a static IP to it. Well, I've contacted my ISP and they said that they can give me static IP. So far, so good. My question is, where ...
17
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7answers
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Why don't more organizations use inside-to-inside NAT or similar solutions to allow NAT hairpins?

Inside-to-inside NAT aka NAT loopback solves hairpin NAT issues when accessing a web server on the external interface of an ASA or similar device from computers on the internal interface. This ...
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1answer
26 views

destinantion-based NAT cisco routers

On a Cisco Router I need to translate "NAT" the LAN IP of some PCs based on the destination e.g. Connecting to 172.16.0.0 /24 Transalte to 172.16.0.100 Connecting to 0.0.0.0 0.0.0.0 Translate to ...
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1answer
576 views

How can I NAT traffic for one VPN to come from a different IP on Cisco ASA?

I have a Cisco ASA firewall between our private network (10.1.0.0/16) and the outside world, and multiple VPNS going to client sites. Existing: [10.1.0.2...] = source client | [10.1.0.1 ASA ...
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Do I need 2 NIC cards to forward public IP to private IP? [closed]

To use NAT do I need 2 nic cards? I want to use my server for my own business (I don't require VPN) and simply need to forward my public IP to the private IP so that websites show up as ...