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.

learn more… | top users | synonyms

3
votes
1answer
1k views

Configure server to route all traffic through OpenVPN

I have an openvpn setup that is working great. There are some 50 clients connected and everything is handy dandy. I need one of these clients to route all traffic trough the vpn. I setup a ccd for ...
3
votes
2answers
1k views

Initial Cisco ASA 5510 Config

I'm trying to set up a new ASA 5510. I have a pretty simple set up with one /24 on the inside NATed to a DHCP address on the outside. Everything on the inside works and I can ping the outside ...
3
votes
2answers
4k views

Setting up a SIP NAT proxy

We currently run a VoIP server using an upstream providers SIP proxy for our clients who are behind NAT. We now have the problem that we re ending the relationship with the upstream provider, and will ...
3
votes
1answer
5k views

Setup 1:1 NAT using pfSense

pfSense box: Public IPs 208.43.30.118-.117 Private IP : 192.168.1.1 I need to provide 1:1 NAT mapping to a VM in the private network 192.168.1.5 I am unable to get 1:1 NAT working though it ...
3
votes
1answer
2k views

After upgrading BIND: Why is refusing requests? The server is on a NAT'd network

I already have a similar configuration working on another host with BIND 8.4.7 I'm migrating to a new name server so I decided to upgrade BIND to 9.7.3 The configuration is similar to this one, but ...
3
votes
2answers
1k views

Can explicitly ftps via Filezilla but not from code

This was originally posted to StackOverflow, but because the code works and this is most likely a network/firewall issue, I figured I'd ask it here. As the title states, I can connect to another ...
3
votes
1answer
174 views

Finding a private (NAT) host's IP using historic destination data

The issue: An unknown private (NAT) client is infected with malware and it's trying to access a Bot server at random times/dates. How we know about this: We receive bot traffic notices/alerts from ...
3
votes
2answers
4k views

IPSec Tunnel to Amazon EC2 - Netkey, NAT, and routing issue

I'm working on getting an IPSec VPN working between Amazon EC2 and my on-premise. The goal is to be able to safely administer stuff, up/download data, etc. over that tunnel. I have gotten the tunnel ...
3
votes
3answers
3k views

Manual NAT on Checkpoint (Redirect all http requests to a local web server)

We have a proxy server in our internal network and I want to redirect all internet http requests to a web server in local network. It'll be like a Network Billboard that says "No direct connection is ...
3
votes
2answers
2k views

VirtualBox - Static Guest, accessible from host

I'm using VirtualBox trying to set up Windows as my dev environment, but an Ubuntu VM as my "virtual server". So, Windows 7 is my host OS on my laptop. My guest OS is Ubuntu, which will run my LAMP ...
3
votes
1answer
175 views

Logging NAT mappings on a Mikrotik router

I am looking for suggestions on how to configure a Mikrotik router to log NAT session setup and ideally teardown. However, setup only is sufficient for my immediate needs. I found a method to log ...
3
votes
0answers
679 views

ASA 5505: How do I access the DMZ web server from the inside using the public IP?

We are using a 5505 ASA Sec+ (8.2). There are three interfaces: inside (172.17.0.0/24), dmz (172.16.0.0/24) and outside (1.2.3.4 for the example). There are static NAT rules set up translating ...
3
votes
1answer
83 views

Reaching out DHCP relayed hosts

I have one primary server (DHCP) and one secondary (DHCP-RELAY). Majority of hosts are served from primary (wirelessly), however there are a few (wired ones) which get their IPs from secondary. ...
3
votes
0answers
519 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 ...
3
votes
1answer
354 views

NAT box load-balancing with iptables and 4 DHCP uplinks

I am trying to configure a router which provides Internet to a couple hundred users. This router has 4 basic cable uplinks at its disposition, which all use DHCP and have a capacity of around 10/1 ...
3
votes
0answers
541 views

Oracle Solaris 11, ipnat - rdr not working with remote destinations

I'm trying to reverse proxy traffic coming in on port 8100 at one machine to another. The receiving host is an oracle exclusive zone as is the destination machine. On the incoming zone I have ...
3
votes
2answers
1k views

sonicwall vpn and NAT

I have a site-to-site VPN set up with a vendor. Let's say the tunnel endpoints are 192.1.1.101 on my side and 192.1.2.0/24 on the vendor's side (which get's NATted to their LAN of 10.x.x.x). This is ...
3
votes
5answers
3k views

Open ports broken from internal network [duplicate]

Quick summary: Forwarded port works from the outside world, but from the internal network using the external IP the connection is refused. This is a simplified situation to make the explanation ...
2
votes
1answer
12k views

Why Are There Only 65,535 Ports, and Will We Ever Have More? [closed]

I understand the original reasoning behind having 65,535 ports per IP address: this is the highest number that can be represented by a 16-bit, or 2-byte, number, and it wasn't conceivable that ...
2
votes
4answers
1k views

Is there still any legitimate reason (in 2011) to use proxy servers instead of NAT for sharing an internet connection?

Proxies were around before NAT, and so early on in the internet, they were popular ways to get an entire network online with only a single public IP. NAT initially required complex software and/or ...
2
votes
4answers
11k views

How to properly nest a wireless router behind a wired router? [closed]

I wish to repurpose a wireless router to serve as a wireless access point behind a wired router (serving as gateway to WAN) so that I don't have to buy more hardware and recapture value on prior ...
2
votes
3answers
3k views

Iptables massive 1:1 NAT

I have to connect two LANs: LAN1: 10.10.0.0/16 and LAN2: 192.168.0.0/16. I can't do simple routing, because 192.168.0.0/16 net is prohibited in LAN1, so I am thinking of using Full cone nat (1:1) to ...
2
votes
3answers
3k views

Windows Computers Joined to a Domain Behind NAT

If I have some Windows XP machines that are behind NAT, will all services still work as normal such as file sharing, printing, etc. The setup would be something like 192.168.20.0/24 NAT`ed to ...
2
votes
2answers
4k views

Server becomes unreachable and comes back up on its own (most likely a network issue)

I'm having a strange problem with a server I have sitting at my workplace (it's behind a NAT, if that's important). The issue is that at some times, it becomes unreachable and then comes back up ...
2
votes
2answers
370 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 ...
2
votes
2answers
1k views

Iptables string

I have an iptables rule like this: iptables -t nat -I PREROUTING -p tcp --dport 80 -s 192.168.1.2 -j DNAT --to-destination 192.168.1.1:80 it works perfectly.. but I want to redirect only for one ...
2
votes
1answer
107 views

How can I Nat certain boxes in my datacenter so that they are coming from a single IP

I want to NAT a certain group of servers in my datacenter so that they all access clients from a single IP. This will make it much easier for documentation that we provide clients. However there ...
2
votes
3answers
853 views

Can I have web server on a home network with 1 public IP address? [closed]

I've got a fairly standard home network with a modem from my ISP, which is connected to a router which then provides NAT to about 3 PCs and laptops. There's a possibility to obtain one public IP from ...
2
votes
4answers
799 views

Is NAT completely transparent to a host?

Can we find a sequence of packets that a host can transmit to determine whether it is located behind a NAT box? I mean, without any special server support like STUN.
2
votes
1answer
3k views

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. ...
2
votes
3answers
9k views

How to implement Nat loopback/reflection?

I'm trying to access a server on my LAN via its public IP address. External clients can connect just fine, but I'm unable to do so from within the LAN. There is a separate rule in the NAT settings of ...
2
votes
1answer
6k views

Cisco ASA 8.4 port forwarding

I am having trouble port-forwarding on an Cisco ASA from a host on the internet to a host on the internal network. The outside interface of the ASA is assigned via DHCP. Is there something else that ...
2
votes
2answers
2k views

UDP and NATs - is the timeout bidirectional?

Is the timeout for an UDP connection through a NAT reset every time a packet is sent OR received by the client, or are there any (common) implementations that require the client to actively send ...
2
votes
3answers
13k views

VPN software similar to Hamachi, Remobo or GBridge?

I am looking for a VPN software that will run on Windows (Mac/Linux would be a bonus), that are similar to other packages such as Hamachi that will automatically work behind a NAT or Firewall. ...
2
votes
4answers
1k views

Networks, subnets, routing and NAT

What I'm going to ask may be trivial but I really need to understand cause my teacher is confusing me! That's the problem. I got 2 private networks The first is a class C network and the address is ...
2
votes
3answers
6k views

Reloading NAT configuration on a running VMWare Server 2.0.2

I have a server running VMWare Server 2.0.2. The host is Debian Lenny. I have 15-20 virtual machines running, all attached to a single NAT network (named vmnet8). I have configured VMWare's NAT (the ...
2
votes
1answer
244 views

Does the ELB also route outbound reply traffic in AWS

I have been trying to understand how routing works in an AWS VPC with public/private subnets. I have a setup as recommended by amazon with an ELB and NAT in the public subnet and the webserver in the ...
2
votes
2answers
3k views

Make CentOS 7.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 ...
2
votes
2answers
151 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 ...
2
votes
2answers
299 views

Networking several devices with the same IP

I have a bunch of embedded devices that I need to flash with a custom OS. On each device, the boot-loader (U-Boot) has a fixed IP of 192.168.100.2 and on boot it looks for a TFTP server at ...
2
votes
2answers
4k views

How can I setup a Firewall without NAT?

We have 16 IP addresses from our ISP, and are setting up a SonicWall Firewall. I'd like to have the SonicWall do NAT for the LAN, but act as a firewall only (no NAT) for the servers which are using ...
2
votes
3answers
601 views

Port Forwarding

Assuming port forwarding is done on router, can the router forward if the data is coming from local machine, rather than remote. For example: Sender targets ip like:88.251.xxx.xxx, port 8999. ...
2
votes
3answers
4k views

Routing application traffic through specific interface

First question here, so please go easy: I have a debian linux 5.0 server with two public interfaces. I would like to route outbound traffic from one instance of an application via one interface and ...
2
votes
1answer
3k views

Marking packets with iptables with a NAT

I have to write bash scripts for a router to control bandwidth limitation for a given user on a given domain name. For this, I'm using iptables to mark the packets incoming from a restricted domain ...
2
votes
2answers
872 views

Linux Routing with two NICs (LAN vs Internet) with NAT and bridging for VMs

My Setup: There is only one physical machine in this setup, a Host System for Virtual Machines (VMs) with two network adapters. One NIC (eth0) is connected to an internal network (LAN subnet, e.g. ...
2
votes
3answers
5k views

Is it possible to configure a reverse VPN tunnel?

Basically, my goal is to have a 100% portable and independent server. I'm building it using a Raspberry Pi powered by solar panels and batteries, and it is to be connected to the internet using a 4g ...
2
votes
1answer
357 views

What is the correct iptables rule when NATing multiple private subnets?

I have a Centos minimal 6.5 acting as a router. eth0 is connected to a Cisco switch trunk port, allowing VLANs 200-213. I have several VLAN interfaces just as this link suggests: ...
2
votes
1answer
7k views

How to Configure Source NAT (Private IP => Public IP Outbound)

I'm running VMWare ESXi Free and have Zentyal SBS 3.2 running as a Gateway. I have 5 Public IPS (CIDR/29, let's call them 69.1.1.1 - 69.1.1.5) and currently Zentyal is bound to 69.1.1.1 as the ...
2
votes
2answers
592 views

How are connections differentiated from behind NAT routers?

Background: I have a very simple server program written in PHP. It's mostly working, but only as long as there is not more than one client per site. Questions: How does a NAT Router (typical SOHO ...
2
votes
3answers
793 views

NAT: If two hosts initiate a connection to the same IP:PORT, with the same source PORT, how does the router handle it?

I was just thinking and that idea came to my mind. Let say I have hosts A and B inside my local area network. I have a Router, and a host C in the internet. I know that when initiating the ...