Network Address Translation, a technology used to translate a private IP address into a public IP.

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35
votes
9answers
95k views

How to do networking between virtual machines in VirtualBox?

I have two virtual machines in VirtualBox. I would like to do networking between them. For the moment I have the default configuration on both, but they seem to have the same IP-address 10.0.2.15. I ...
16
votes
5answers
11k views

SSH access to office host behind NAT router

I would like to access the ssh port of my office linux host from home. Unfortunately the host is located behind a NAT router. So, the IP address is not publicly available. There is however access to ...
13
votes
2answers
4k views

How will home networks work in the IPv6 world?

Right now, I have a home network setup behind a Netgear router. That router has a public IP address I get from Comcast. I also have a computer setup on my home network running Linux that runs a DHCP ...
11
votes
4answers
62k views

Does mailx send mail using an SMTP relay or does it directly connect to the target SMTP server?

Suppose i send a mail using the following the following command: mailx person@x.com then does mailx first try to find out the SMTP server of my ISP for relaying the mail or does it connect ...
11
votes
1answer
11k views

How does a NAT server forward ping ICMP echo reply packets to users?

NAT uses an IP address port number combination to hash the outgoing requests. Since ping requests consist of ICMP echo request packets, they do not have any associated port number. How does a NAT ...
10
votes
8answers
36k views

How to get my external IP address (over NAT) from the Windows command-line?

The Windows "ipconfig" command can only show me the parameters from the Ethernet interfaces from my machine (even with the ipconfig /all argument). It can show detailed information about the ...
10
votes
5answers
3k views

Does NAT provide security?

I'm following discussions about the IPv4->IPv6 transition, and IPv6 doesn't seem to like NAT at all. I've always thought that NAT was helpful in v4 for some security, I know it doesn't really hide ...
9
votes
2answers
10k views

how to access samba on a guest Linux behind the VirtualBox NAT?

On my laptop, I'm running Ubuntu 9.10 under WinXP using VirtualBox 3.1.2. I want a setup where: The guest can freely access the internet. The host can access the guest files via Samba. The setup ...
8
votes
2answers
554 views

What do the various IP addresses mean?

When I visit a website (e.g. whatismyip.com) it states that my IP address is 13.151.xxx.xxx. However, when I run ipconfig, my IP address is 192.168.0.xx for IPv4 and my DNS adress is 202.xx.xxx.xx. ...
7
votes
7answers
21k views

How can I make my home PC a web server?

I am running Apache Tomcat on my PC. My PC is connected to a router in my house and the router is connected to my ISP. Now I want to run a server on my pc so that my frined can view my site hosted on ...
7
votes
3answers
14k views

Connecting to VirtualBox guest (ubuntu) from host (osx) via NAT?

I have a VirtualBox guest (running Ubuntu) configured with NAT through my host laptop (running OSX). It was my understanding that with NAT configured, I could access the guest from the host (w/o any ...
7
votes
3answers
43k views

How will a router with NAT disabled behave?

Just a quick, somewhat newbie question... I noticed that my home router has the option to disable NAT. How will the router behave with NAT turned off? Will it simply broadcast all incoming traffic to ...
7
votes
2answers
3k views

How does the router know which device to send packets to? [duplicate]

my question does not concern how it moves through the internet, but how it moves through the router to a certain device. All devices connected to a router in a home network have the same external IP. ...
7
votes
2answers
5k views

How is double NAT bad practically?

As the ISP-provided modem was generating pretty weak WiFi signal I've disabled its WiFi function, bought an Apple AirPort Extreme and connected it's WAN port to the modem. Now everything works just ...
7
votes
5answers
13k views

Is it possible to host a web server from behind a NAT

My PC is behind a NAT router that has a public IP address. If I want to host a website then I believe I need a domain name which I can purchase from some site which would pledge to resolve all DNS ...
6
votes
4answers
4k views

Why do we have NAT if we could just assign a public IP address?

If the private address block is simply used to allow the router to determine where packets can and cannot be forwarded from (because private addresses need to be unique on their own network, but can ...
6
votes
7answers
8k views

VMware Player loses internet connectivity

Periodically, the internet simply stops working in my virtual machine, and the only way I can get it working again is to restart the host computer. Since I use the virtual machine specifically for ...
6
votes
4answers
885 views

Connecting to home computers behind a router

I have a home network setup behind a NAT router with two linux boxes. Occasionally, I want to ssh to them from outside the home network, but neither have a public IP address. What's your ...
6
votes
3answers
8k views

Bridged vs. NAT: a Virtualbox and VMWare Comparison

I installed VMWare Workstation 7.1.x and Virtualbox 4.0.8 on two different hosts, so I could compare. I set the virtual network adapter on both to NAT, which was successful for both. The result: ...
6
votes
2answers
8k views

How to open file and printer shares to the internet?

i tried to make file and printer sharing open to the internet on NT3.51 in 1998, but it just refused to actually ever work. Are are the IP ports and protocols that must be port-forwarded to make file ...
6
votes
3answers
251 views

Two websites give different values for my IP

I just found something curious: http://whatismyip.org/ says my IP address is 82.44.14.246 http://www.whatismyip.com/ says my IP address is 31.52.118.197 I'm based in the UK and behind a router ...
5
votes
3answers
6k views

VirtualBox NAT port forwarding on Ubuntu 64?

I have an Ubuntu 9.04 desktop 64-bit guest OS running on an Ubuntu 9.04 desktop 64-bit host OS (yes, the same OS). I'd like to run a web server on the guest and make it accessible through NAT on the ...
5
votes
2answers
4k views

Connecting to a VirtualBox machine from the host, using an ip address

In a macbook host, I run VirtualBox having a guest ubuntu server, with a NAT network setting. In the virtual machine application "Parallels", I would get on the host an IP address of the guest, to ...
5
votes
2answers
293 views

How to block a particular computer behind a NAT

I run a small hostel and have the following network configuration: Router1 (192.168.1.1) ─┬─ (192.168.1.2) Ubuntu Samba+SSH Server ├─ (192.168.1.X) Router 2 (192.168.2.1) ─┬─ ...
5
votes
3answers
2k views

NAT and UDP replies

Sanity check please. If I send UDP packets from Machine A behind a NAT to Machine B's port N, where Machine B is outside the NAT (elsewhere on the Internet), can I reasonably expect that NAT to pass ...
5
votes
1answer
503 views

Rackspace Firewall/Gateway Setup

I have rackspace account and wish to have this sort of setup: Firewall/Gateway eth0 - Public IP (56.X.X.X) eth1 - Private IP (10.X.X.X) Ubuntu 10.10. Accepts connections from the internet and ...
5
votes
4answers
338 views

What hardware and OS should I use for my home router/server setup for good filesharing capabilities?

I would like to set up a new server at home that should be able to perform the following tasks: Act as firewall/router/NAT for my home network Share lots of files, mostley music Misc. other stuff, ...
4
votes
4answers
4k views

how to ssh two computers behind NAT and Firewall, without third computer

I am trying to ssh into my Linux box at home. My home is a dorm-style environment - NAT and Firewall with personal laptop running Arch Linux. My work is corporate style Windows 7 - NAT and proxy ...
4
votes
4answers
3k views

I installed an Airport Extreme router and got a warning about “Double NAT”. Why is that bad?

I've got a relatively complex home office/small office network -- I use two NAT (Network Address Translation) routers/firewalls to provide a DMZ (DeMilitarized Zone) for a cheap sacrificial web ...
4
votes
3answers
12k views

Is it possible to get the NAT Ip Address?

is it possible to get my nat ip address across the Internet? I know I can see my ISP address but not my internal address. I remember seeing this done one time but I am thinking it was a java applet ...
4
votes
5answers
984 views

VNC as a Support Tool Over the Internet

I'd like to set up an environment where I can use VNC to remotely support my clients over the internet. No VPNs and no port forwarding involved. I've used the UltraVNC repeater in the past, but the ...
4
votes
2answers
3k views

No internet on host OS (OS X Lion) when VMware Fusion is running

I have installed OS X Mountain Lion as a VM in VMware Fusion (version 4.1.2) for environment testing. The host OS is OS X 10.7.4, and is connected to the internet via a wired connection (in fact I get ...
4
votes
1answer
7k views

How can I connect DLNA devices through NAT?

I have a Windows 7 PC running Serviio as a DLNA server. I have a Samsung I9100G running Skifta as a DLNA renderer (client). My network topology: At the moment, I can connect and watch my videos ...
4
votes
1answer
1k views

Configuration for public (external) access to ubuntu guest on ESXI 5

I am setting up a demo system on a leased dedicated server. System consists of : ESXI host with 1 NIC assigned (so 1 Static IP) 64 bit Ubuntu guest as server I installed and configured the system ...
4
votes
3answers
388 views

Set up Linux box as WAP for MyBookLive?

I inherited an old Linux box as well as a MyBookLive and would like to make the MyBookLive available over my wireless, essentially using the Linux box as a gateway. I just wiped the Linux box (home) ...
4
votes
1answer
4k views

VirtualBox NAT over proxy

I use VirtualBox 4.1.8 on a Ubuntu 10.04 host system. I have an HTTP proxy server on the host system. How do I configure the VirtualBox to NAT the virtual machine's network and use the HTTP proxy for ...
3
votes
3answers
1k views

How is traffic separated between internal and external IPs?

If I ping 192.168.0.X from my home network then it will attempt to look within my network for that address and not the external WAN IP. However I can ping 74.125.224.163 and it will ping google.com. ...
3
votes
3answers
1k views

How can my router have the same MAC as a computer in the LAN?

My ISP refused to give out a new IP when I switched from just having one computer in the LAN to using a router in spite of me doing a few releases and renews. So I tried an a little unorthodox ...
3
votes
2answers
2k views

VirtualBox network configuration

I have a CentOS 6.1 virtual machine, virtualized with VirtualBox on Windows XP. This machine hosts my local development MySQL server. I'd like to find the correct network configuration, so that: my ...
3
votes
4answers
3k views

How to ssh into home LAN behind ISP NAT (no public IP address)?

My property management company provides free internet access. All the apartments in many buildings are behind some common NAT, so none of us have our own public IP addresses. Thus, services like ...
3
votes
2answers
3k views

Virtualbox: NAT networking suddenly stopped working for all Windows guests, Linux guests still OK

My host is an out-of-the-box Ubuntu 12.10 simply connected to Wifi. I installed VirtualBox, and then a few Linux and Windows 7 Pro guests on it, all with default VirtualBox options (NAT). I reboot ...
3
votes
1answer
598 views

How would I test to see if I'm behind carrier grade or regular NAT?

Inspired by the comments to this answer and its question. Some of my local ISPs are using carrier grade nat, and as someone who occasionally runs his own servers, remote support, it would be highly ...
3
votes
2answers
4k views

ssh through a router without port forwarding

I have a linux server, and I want to put it in a home network behind a router. I need to ssh to this server sometime from outside, but I don't want to set up port forwarding because I don't have ...
3
votes
3answers
489 views

How to host a webserver through NAT?

I've come across many "How to host something while behind NAT" but none are like my situation (I knew how to host a server through a simple NAT anyway). This is how my ISP works... First, start off ...
3
votes
2answers
4k views

Bridging my laptop's wireless and wired adaptors

I would like to be able to connect a desktop computer that does not have a wireless adapter to my wireless network. I could just run a network cable from my ADSL/wireless router to the desktop ...
3
votes
1answer
8k views

Accessing a website via the webservers public IP from a PC within the same LAN

If two machines reside on the same LAN (a PC and a Webserver) why is it necessary to enable ‘NAT loopback’ on the router in order for the PC to access the website hosted on the webserver using the ...
3
votes
1answer
9k views

Port Forwarding from inner network to inner network (hairpin NAT)

I've successfully setup a port forwarding on a Mikrotik router that translates every request going to WAN ip address on port 8844 (let's say: 20.20.20.22:8844) of mikrotik to the local ip address and ...
3
votes
1answer
616 views

Redirect Port on Mac to VMWare

So...I have started working as a front-end developer in a shop that does .NET. I use a Mac and have a VMWare image with Visual Studio and the project on it. The project runs great. However, I was ...
3
votes
3answers
232 views

Find out how many NATs exist between my home machine and the Internet

Are there any tools/utilities that can help me find out how many NATs exist between my home machine and the public Internet? Any references to protocols that would help me figure this out would also ...
3
votes
1answer
209 views

Run a server behind router

I own a virtual private server. I currently want to run a server on my local computer (behind a router that I don't have admin access to so I can't port forward). Can I use the virtual private server ...