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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How many valid NAT mappings can a common NAT support?
How many NAT mapping rules (that is, mappings between internal, private IP:PORT, and externally mapped IP:PORT) can a common NAT box support?
Is there a limit in such number (that is, how many rules ...
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5answers
369 views
Isn't NAT a MUST when a LAN uses rfc 1918 private IPs?
Isn't NAT a MUST when a LAN uses rfc 1918 private IPs? Can an organization assign its hosts with private IPs and still communicate with the external world without NAT?
how can an internal host with a ...
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2answers
1k views
Advanced routing problem
I have 2 internet links using 2 ADSL routers and I need to give access to the Internet for the 192.168.0.0/24 network.
I have to route outgoing traffic based on port number, protocol, …
using ...
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1answer
128 views
Authorative DNS behind NAT possible?
I am currently running an authorative Bind9 DNS server for a bunch of domains. This authorative server currently replicates to a couple of slaves which are then used to meet the subnet requirement for ...
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2answers
2k views
How to get VirtualBox NAT working with actual client IP's?
I'm using Virtualbox 4.0.10 on a Debian Squeeze box. I have a Windows 7 VM that I use to host a game server. After setting up NAT and port redirection, clients can connect to the VM, but the game ...
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2answers
568 views
Exposing a WebServer behind a firewall without Port Forwarding
We are deploying web applications in java using tomcat on client machines across the country.
Once they are installed, we want to allow a remote access to these web applications through a central ...
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1answer
1k views
pfSense router on a LAN with two gateways
I have a LAN with an ADSL modem/router on it. We have just gained an alternative high-speed internet connection at our location, and I want to connect the LAN to it, eventually dropping the ADSL.
...
3
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1answer
366 views
How do IPv4 only applications work on IPv6 only hosts?
Is there any way for IPv6-unaware applications to continue to work on a host with only IPv6 connectivity?
The IPv4 implementation of the host could know about the problem and just encapsulate the ...
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3answers
9k views
Create NAT rule and security policies for port 443/80 on a Cisco ASA 5510
I've been trying to setup NAT and give access to a public IP address to my local network, I just can't get it to work. It's my first time using a Cisco firewall.
Thanks for your help!
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3answers
2k views
Connect to Teredo-enabled server behind NAT
I've got a Vista64 machine behind a NAT router connected to the IPv4 Internet.
Teredo is enabled on my machine and I've got a IPv6 address with 2001:0: prefix. I can ping several servers in the IPv6 ...
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1answer
121 views
Dual Cisco Router Stateful Firewall
At my company we have a single Cisco 3925sec/k9 router running BGP with 2 ISPs.
Now we want to purchase a redundant router of the same model to eliminate a single point of failure.
I can set up BGP ...
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1answer
166 views
Can I enable NAT on a Cisco ASA without breaking connectivity?
Sorry for the noob question, I haven't done this in years...
I have a Cisco ASA with a working VPN, which I set up like five years ago, and I would like to forward http through to an internal IP ...
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1answer
118 views
What is the motivation for DNS64?
I'm wondering why NAT64 needs something like DNS64 at all.
Couldn't an IPv6-only host, when trying to reach an IPv4-only host, just embed the IPv4 address of the target host in an IPv6 packet (by ...
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1answer
375 views
Traffic blocked between VLANs despite security-level difference on ASA 5510
I have an Cisco ASA 5510 configured thus:
interface Ethernet0/0
description ### Trunk for inside, wlan ###
speed 1000
no nameif
no security-level
no ip address
interface Ethernet0/0.10
...
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1answer
2k views
Windows 7 with internal port redirection, is it possible?
I received a request from one of our developers that I am having trouble solving.
Here in the office they use linux desktops and I can forward the localhost:80 via a iptables nat to localhost:8080. ...
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1answer
2k views
Connecting a physical ethernet port to a VMware virtual switch?
I hope this is the correct place for this question. I thought about posting it to Super User first, but it seems to be more relevant to this place. Anyway, here goes:
I need to connect a device ...
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1answer
822 views
Linux IPv6 Transparent Proxy (but Linux doesn't support NAT on IPv6!?)
On Linux I can make a transparent proxy simply by adding a iptables -j REDIRECT command.
To my surprise, I am needing to support IPv6. Simple enough right? iptables6 -j REDIRECT command not ...
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2answers
1k views
Forward differing hostnames to different internal IPs through NAT router
I have one public IP address, one router and multiple servers behind the router.
I would like to forward differing domains (All using HTTP) through the router to different servers.
For example:
...
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1answer
286 views
Do NATs verify the source port of a SYN received after a SYN has been sent?
I'm unsure of whether this question is more appropriate for stackoverflow or serverfault. If you think it's more suited for stackoverflow, let me know and I'll delete this and move it over.
I have a ...
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3answers
1k views
Service can't connect to self using public IP, NAT problem
I have a dedicated server from serverloft.eu, but due to some network security I cannot use bridge networking on my server.
So I have setup all my IPs to the main eth0, and used NAT to forward trafic ...
3
votes
1answer
446 views
Dynamic DNS with split horizon DNS or hairpin NAT
I would like to host a CalDAV and CardDAV server for devices that will roam between being on the LAN to outside my network (such as my iPhone and laptops). A static IP is prohibitively expensive.
I ...
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1answer
201 views
Forward specific network traffic to other server
Is it possible to redirect incoming traffic on a specific port of my Ubuntu Linux server machine to another server (that has another public IP address and is located at another site)? I'm running a ...
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2answers
958 views
iptables NAT with multiple interfaces
I have an ubuntu 10 machine I'm trying to set up with NAT.
eth0 is the WAN interface, that uses DHCP.
eth1, eth2, eth3 are LAN interfaces. They are connected to 192.168.0.50, .51, .52 respectively.
...
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3answers
402 views
how to connect 2 independent computer networks?
I have 2 independent networks that are connected to internet. Each systems in a network can connect to the internet through the corresponding router/NAT device. i wish to connect these two LANs. I ...
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2answers
947 views
fwbuilder: port forwarding incoming 222 port requests to a local machine 22 port
I am using fwbuilder to setup my iptables rules for a public server. The idea is to forward external requests from the 222 port to a local machine's ssh port. The settings i used are:
NAT section
...
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2answers
730 views
Stateless NAT with Linux
There seems to be some rumors floating around that stateless NAT exists in linux in a non-depreciated form (unlike iproute2) as of 2.6.24:
http://lwn.net/Articles/254559/
...
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2answers
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Linux IPTables Destination NAT with Asymmetrical Routing?
What is the proper way to handle DNAT when traffic leaves a different interface than it arrived on? When this happens it seems the reply doesn't have the source address replaced automatically as it ...
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1answer
626 views
ESXi :: ASA NAT + Switch :: Setup on .27 IP Block
Just bought an ASA 5505 and a separate gigabit switch, along with a Dell R610 virtualization server to replace existing bare metal web server.
There will be 2 physical machines, R610 running ESXi 4.1 ...
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2answers
2k views
Ubuntu Server Port Forwarding the easy way?
I have an Ubuntu server (10.04) running nat and I understand how to forward ports using iptables which works fine and is only mildly painful. What is "the easy way" of doing this? Is there some nice ...
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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 ...
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1answer
8k views
How are cellphone IP addresses assigned?
When my cellphone accesses a website via the tower and its GPRS gateway, NAT ensures that the sites receive a public IP. Would all phones using a single tower have the same IP?
If yes, then how can ...
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1answer
117 views
NAT with multiple gateways
I have the following setup:
My Lan is 10.56.8.0/23
I have a gateway with internet access(INETIP-A) and the LAN IP 10.56.9.1
I have another gateway with internet access(INETIP-B) and the LAN IP ...
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2answers
224 views
How can private IPV4 addresses get past iptables NAT (tcp RST,FIN)
I've got a router performing simple NAT translation using iptables
iptables -t nat -o -j MASQUERADE
This works fine almost all of the time except for one particular case where some TCP RST and FIN ...
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1answer
1k views
DNS Server Behind NAT
I've got a Bind 9 DNS server sitting behind a NAT firewall, assume the Internet facing IP is 1.2.3.4
There are no restrictions on outgoing traffic, and port 53 (TCP/UDP) is forwarded from 1.2.3.4 to ...
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2answers
300 views
Are DNAT and REDIRECT equivalent when applied to locally destined traffic?
In setting up our OpenStack environment, I ran into a problem that was preventing instances from contacting a server running on the host. The metadata service (which exposes an HTTP API) runs on port ...
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1answer
2k views
Asterisk SIP/2.0 401 Unauthorized
I'm running into a funny little issue with Asterisk 10.3, but it seems to be applicable to 10.4 as well.
The server running Asterisk was relocated from a VPS to dedicated hardware, and now only 1 of ...
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1answer
633 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 ...
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2answers
739 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 ...
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2answers
722 views
public ip resolves externally but not internally
I have a one to one NAT on pfsense that assigns a public IP to an internal IP (running a web server).
When I open the public IP from an internal machine, it will not resolve to the internal IP, ...
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2answers
980 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 ...
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1answer
2k 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
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1answer
715 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
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1answer
162 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 ...
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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 ...
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1answer
216 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 ...
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3answers
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How do I configure my router under another to avoid NAT issues?
I'm sorry if this has been answered before; I tried looking but couldn't find a solution. I'll try and explain as clearly as I can.
I've recently purchased a Rogers Mobile Rocket Hub and it's ...
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2answers
213 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 ...
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2answers
123 views
How widespread is double (or more) NAT/PAT?
Background: I'm working on a hole punching service with UDP, and in order to differentiate users under the same public IP, I've thought of making the user also send their local IP. That way, I killed ...
2
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2answers
455 views
Domain Controllers over a NAT
My organization is in the process of setting up a new network at a hosting provider for a very large application project. Since the whole system uses Active Directory we are planning on using a pair ...
2
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3answers
676 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 ...
