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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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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561 views

How to stop NAT dropping idle connections?

I have a TCP connection that can be idle for many hours. The traffic is flowing from the server to the client only. One might say it's kind of push notification. My home router, however, tends to ...
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1answer
1k views

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
106 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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121 views

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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0answers
235 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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0answers
167 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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1answer
1k views

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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1answer
38 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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0answers
226 views

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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0answers
266 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
120 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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2answers
211 views

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 ...
2
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2answers
223 views

Setting up NAT for multiple isolated networks with iptables

I have a gateway machine connected to multiple internal networks that I would like to set up NAT on. The catch, though, is that these networks need to be isolated from each other, which I haven't been ...
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1answer
88 views

Iptables & NAT retain original destination IP?

I've got a webfacing server that I've chopped up into guests, one of which is running apache with some pretty basic virtualhost config. I have redirection working, but my virtualhost config needs the ...
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1answer
199 views

ADSL Router - Access External IP internally

I have a problem when I'm doing an access using my DNS hosted at another server, which performs a redirect to my internal network. example: User attempting access to internal DNS: intranet.site.com: ...
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1answer
96 views

Forwarding ports from server with 2 internet connections

I have 3 interfaces on my main server, first is used for the local network, second and third are internet connections (each has its own ip routing table): eth0 192.168.0.1 eth1 9.9.9.9 eth2 7.7.7.7 ...
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2answers
1k views

NAT Gateway - Maximum connection limit

I know just enough networking to be dangerous. The nitty gritty low level details of NAT are not something I am particularly knowledgeable about. I accidentally found myself in a discussion earlier ...
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4answers
789 views

Linux - two subnets, one interface, one gateway - NAT the additional subnet

We currently have a few servers that all use the same LAN: Host1: eth0 10.0.0.1/24 Host2: eth0 10.0.0.2/24 Host3: eth0 10.0.0.3/24 Gateway: 10.0.0.254 We want to run some VMs (VirtualBox) on these ...
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33 views

making a software router for my private network [duplicate]

give me suggestion on this problem. I have 2 nic cards public ip (eth1) and private ip (eth2). now i have a linux system having centos 6.4. I made this system software router so can access internet on ...
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3answers
2k views

iptables: combine SNAT with network remapping for OpenVPN

[Apologies for the long prelude; question halfway down.] I have a working OpenVPN setup whereby a VPN server pushes a route back to one client (hereafter called the “router”) which can then expose ...
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1answer
289 views

Change IP address of incoming packet with iptables

I have a server (S1) inside LAN, where a router is outside my control. On a server openvpn is installed and I can login with ssh to it. There is another server (S2) on the LAN, and I want to forward ...
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1answer
2k views

Do you need to enable ALG features in order to NAT H323 traffic on a Juniper firewall?

Can you NAT H323 traffic if ALG features are disabled (ultimately disabled H323 traffic inspection capabilities), or is that feature required in order to NAT such traffic?
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1answer
114 views

Advanced NAT - Mix PAT with NAT

I've just configured an Ubuntu Server as a router with NAT/PAT, and I'm trying to do the following thing: I work for a school that has divided its network into smaller networks connected by routers. ...
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1answer
265 views

How to configure dns in centos to resolve internal lan ip [closed]

i have a router with nat to web server inside LAN. Also i have internal DNS server on centos. When i try to access web server from internet it works fine, but when i try to access from the LAN, DNS ...
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1answer
394 views

Windows Server 2012, Hyper-V, how to use 1 IP for all VMs? [closed]

I am running Windows Server 2012 to host several VMs. However, our ISP has only assigned us two IP addresses, one of which is assigned to the host o/s (Windows Server 2012). How can I set this up so ...
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3answers
648 views

want to Make software router having two nic cards using centos 6.4

I'm new on CentOS. I have a CentOS 6.4 system having 2 NIC cards. I want to setup a gateway so I can get internet from public ip over 1st nic card (eth1) and forward the network over 2nd nic card ...
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1answer
162 views

Enable route between subnet

I have a Centos server with three NIC cards. ETH0 Public IP xx.xx.xx.xx1/xx.xx.xx.xx2 (with two public IP) EHT1 Local Subnet 192.168.80.0 (DHCP server listening on this interface) ETH2 Local ...
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2answers
2k views

FTP - 500 I won't open a connection to xx.xx.xx.xx

I'm running a server on AWS and I'm connecting out to a partner's FTP site (not much idea what they are running). My server has an elastic IP. In the results below xx.xx.xx.xx is the internal IP ...
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1answer
329 views

Asterisk behind a firewall

we have a bit a sticky problem on our Asterisk server, which we are struggling to resolve, I'm hoping someone with more knowledge than me can help. We are running Asterisk 1.8.23.0 on Centos 6.4 and ...
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1answer
441 views

How do I configure routing from host system to virtual machine?

I have an Ubuntu host system that is running a MAC-VLAN virtual interface on top of eth0 interface, ipv4 routing is enabled. Also, this system has a Docker (LXC) container running: docker0 Link ...
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1answer
64 views

Port forwarding to the local network machines for local network users

All machines in my network based on linux. Main server has 192.168.0.1, mail server has 192.168.0.2, client machine has 192.168.0.3 ip. I've added iptables -t nat -A PREROUTING -d 192.168.0.1 -p tcp ...
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2answers
327 views

Remote Management (VNC-style) without Port Forwarding [closed]

Is there a way of setting up a VNC-style server (RDP would do as well) on machines behind NATs, and have access to them? Should be technically possible by having outgoing connections from the NATed ...
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2answers
420 views

Web server behind NAT, how to listen for public IP address

I have a debian web server (nginx) running behind a firewall using NAT. The web server is hosting several sites that require SSL and their own IP address. I'd like to have the SSL sites listen to only ...
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1answer
175 views

Forwarding everything from external DMZ ip to NAT ip using iptables

I know there are a lot of questions about this, but I still struggling to get it working. I have a firewall which has 3 external IPs. (IPs have been changed randomly for security) eth0 Link ...
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264 views

Are my NAT rules in ASA 8.6 correct

I am working on converting some PIX rules to ASA 8.6 syntax. Do the following achieve the goal? Assumptions: outside's IP address is 66.66.66.5/29 The outside IP address I want things translated ...
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1answer
188 views

Accessing Remote Desktop on multiple windows machines behind NAT

Our company has multiple Windows servers running behind a NAT firewall. We would like to provide Remote Desktop access to these machines to our users. One of the solutions is by port forwarding. We ...
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1answer
430 views

Use External DNS Record local with additional subdomains

We have a server in our LAN which is locally available at a fixed ip. We now have a DDNS Service and a port forwarding rule to make the server available from outside. Additional we added subdomain at ...
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1answer
33 views

routing behaviour (PAT/NAT)

|(eth0: 84.23.13.43) +--------------+ | | | NAT router | ...
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3answers
5k views

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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1answer
93 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 ...
2
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1answer
626 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 ...
3
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2answers
568 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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0answers
90 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
457 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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votes
2answers
1k views

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
73 views

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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2answers
449 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 ...
5
votes
1answer
120 views

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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1answer
109 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 ...