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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ASA Static NAT Understanding

I have an ASA configured as follows; Inside: 192.168.0.254/24 Outside: 10.0.0.1/29 (This is routed to the ASA) global (outside) 1 interface global (outside) 2 10.0.0.2 nat (inside) 1 0.0.0.0 0.0.0.0 ...
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Basic iptables NAT port forwarding

I have three machines: A local PC (public IP 1.2.3.4), an Ubuntu 10 Server box in a datacentre (eth0 on 5.6.7.8 public IP), and a third-party server hosting a website outside of my network (let's say ...
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Cisco ASA Nat 8.4

I'm trying to get port forwarding on my ASA working. I'm using: object network server1 nat (inside,outside) static interface service tcp 25 25 and an access list, and it works fine, however, I ...
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158 views

iptables masquerading and rejecting outside-to-inside

I found masquerading made simple howto very useful and everything works just fine. But I'm not sure about the last line: iptables -F iptables -t nat -F iptables -t mangle -F iptables -t nat -A ...
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635 views

Making Ubuntu a minimal NAT?

I need to make a quick-and-dirty NAT out of a Ubuntu 10.10 box. Just "this side is NATted with DHCP handing out 192.168.x.0/24" and "this side gateways to the Internet", and nothing else interesting. ...
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how can I access a webserver running on my NATed VMware Fusion guest from the rest of the subnet?

I am not allowed to run my VMWare guest in bridged mode, and I want to somehow tunnel from an agreed port on the Mac's external network interface to the webserver running on the VMWare fusion guest. ...
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4answers
159 views

How can I copy from a server on the internet to a server behind a router doing NAT?

I have both a VPS and a server behind a NAT firewall. I want to use the server behind a NAT firewall as a backup for the VPS. The VPS needs to be able to initiate the backup process and send the ...
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487 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. ...
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How do I setup Windows Server 2008 as NAT with one NIC?

How would I setup Windows Server 2008 as NAT router with only one nic? I only have access to a server with one nic and I can't add a nic to the server.
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Tunneling XBox network traffic [closed]

My internet access from home is only via a web proxy and a tcp-only socks 5 server. (Long story don't ask). I recently got an xbox and would like to access xbox-live. but I need to route the ip ...
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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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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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305 views

Can't connect to instance via floating IPs, not natting/forwarding properly

I'm having trouble getting floating IPs to work properly on my OpenStack setup. It looks like the controller node (running nova-network) isn't forwarding the traffic to the instances. I've got a ...
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3answers
734 views

Is it possible to capture packets of a Router?

I am facing an issue that some packets sent out to internet from inside network were missing. The pattern we are using is like: Client A ←→ Switch A ← Router A:NAT ← .. Network .. → Router ...
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Netgear VPN LAN2LAN address translation

Here's my question: I have set up a VPN IPsec LAN2LAN (or site2site) with the following parameters: local subnet: 10.178.51.64/27 remote subnet : 10.174.0.0/16 The vpn tunnel comes up correctly ...
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601 views

IPtables SNAT eats packets

I am trying to translate outgoing UDP packets with a source port of X to a source port of Y. I have done this using the following iptables rule: iptables -t nat -A POSTROUTING -s 10.0.0.1 -p udp ...
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iptables: How to forward packets with destination port 80 from eth0 to eth1?

I've http and https traffic coming from several machines to my eth0 on my Linux machine, but I want to forward these traffic to eth1 which has the access to the internet. And do the complimentary ...
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OS X 10.8: redirecting locally initiated ssh connections to localhost:22

I need to hack the OS X pf to redirect all ssh connections from an user to this machine. I want, when doing $ ssh google.com to get the same results as with $ ssh localhost ie a connection to ...
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Understanding ipsec with NAT and dynamic IP's

I'm using OpenSWAN to set up a net-to-net VPN tunnel. I have succeeded in configuring a test scenario as follows: About test and test2: they are Ubuntu 12.04 virtual machines created using ...
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iperf-like bidirectional bandwidth measurement through NAT

I am using iperf to measure my uplink speed between my home PC behind NAT and a fully accessible root server. It does so using a TCP connection. For whatever reason it seems that iperf can only ...
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79 views

Trouble with NATing

I'm a networking noob, so sorry for the very generic title. I have the network setup in the following way: A few details about the network: eth0 on all the devices have an in IP in 10.10.10.0 ...
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465 views

IPTables Internal Load Balancing

I'm trying to setup a load balancing within the same LAN using IPTables (if possible). My idea is to emulate our main load balancer, but within a virtual environment, all the servers are virtual ...
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488 views

Static routes for making hosts on different network accessible

I have a ubuntu router machine with following network settings: br0 192.168.1.15 netmask 255.255.255.0 br0:1 192.168.2.209 netmask 255.255.255.248 I have a pc attached to the br0:1 network with ...
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How can Facebook's session get mixed up because of NAT and/or Proxy

Have received some reports from a customer (a very large company) they reported issues from clients who are using Facebook. These clients claim that once in a while when they log in to Facebook they ...
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problem with NAT in a multiple uplink scenario

I'm trying to configure a linux pc-router that must deal with routing and using NAT to provide connectivity to an internal network (it's also the DHCP server and firewall). In the external side the ...
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How to forward host ports of < 1024 to a VirtualBox NAT-connected machine?

The manual says: "Forwarding host ports < 1024 impossible: On Unix-based hosts (e.g. Linux, Solaris, Mac OS X) it is not possible to bind to ports below 1024 from applications that are not run by ...
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asterisk/freeswitch in nat/no-nat setup

my current setup - i use bunch of sip hard-phones around few offices. all devices have two sip accounts configured - one on internal sip proxy [for calls between the branches], another - at 3rd party ...
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How do you implement NAT-T passthrough on a Juniper SRX series Firewall?

We have 3 juniper SRX-100 firewalls, they are configured like so: FW1 -> FW2 -> INTERNET -> FW3 We would like to create an IPSEC tunnel between FW3 and FW1 passing through FW2 preferably using ...
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324 views

Potential double NAT problems in an OS X office

We have a Comcast SMC Business Gateway router/modem combo in our office, and it doesn't provide much in the way of diagnostic tools or QoS routing. I want to plug another router with Tomato installed ...
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Route-Map vs ACL for Cisco NAT

Is there pros and cons of using route-maps vs access-lists for network address translation on a cisco router?
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NAT GRE (IP protocol 47) over Linux router

I have a host that has a permanent static GRE tunnel to a server on the Internet. Right now the host has its own real IP address. I want to put the host behind a Linux box (Smoothwall), and assign it ...
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63 views

Routing DHCP traffic over the internet

i'd like to know if it's possible for the internet to be between a DHCP server and the network it's "assigned" to? so basically, something like this: -------------- ------------- ...
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Can I use NAT64 to route public IPV6 traffic to internal IPV4?

I have a bunch of public IPv6 addresses and some services that run IPv4 only. Can I use NAT64 to connect these services? Is there another solution like a proxy or something?
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Should we accomodate a customer asking us to NAT servers behind new PUBLIC IPs within a VPN?

We're a SaaS provider, setting up a IPSec VPN between our data center and a customer's site so they can directly access their hosted database server from their LAN. Instead of exposing our internal ...
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548 views

libvirt and network filtering with nat - iptables overrides

At first, I want to say: I know, it was done initially wrong and I want to avoid doing everything again from the scratch because of general downtime. I am running libvirt/KVM on RHEL. I've got VM ...
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715 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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364 views

Ping responses to floating IPs do not reach the router (iptables/nat)

I'm running OpenStack, and I'm having trouble accessing my instances from floating IPs, from anywhere except the network controller node. I've got a Folsom deployment with FlatDHCP, not running ...
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226 views

can't find a way to forward in iptables for specific mac address

I use a linux Centos 6.3 as an Internet gateway with NAT. I want to allow a specific host to have access to Internet, but I don't want to use its IP address since it may get a new IP address from the ...
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96 views

Multiple VMs under VBox, NAT mode, are not responding network requests

I am learning about virtualization. I have been managing real Linux servers for some time but this is the very first time I virtualize, so sorry if I am missing something. My setup is like a ...
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iptables: How to combine DNAT and SNAT to use a secondary IP address?

There are lots of questions on here about iptables DNAT/SNAT setups but I haven't found one that solves my current problem. I have services bound to the IP address of eth0 (e.g. 192.168.0.20) and I ...
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359 views

Forwarding MySQL connection with iptables and differents network interfaces

I have a PC with Ubuntu as a router. It has a 3G connection with a public IP to the Internet, and there is a private wireless subnet. So it has two active interfaces: ppp0: public IP (WAN) wlan0: ...
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Port Routing between different domains

i have a apache server located on a.com:9254 I would like to route a.y.com:80 to a.com:9254. So, I can put all my services under y.com domain. I tried proxy. However, In apache, it looks all ...
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137 views

Forward port on same machine?

I'm trying to forward an existing port for an application which can only listen on one port. The problem is the program and the firewall is on the same computer (Windows Server 2008 R2). For ...
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ASA: How to connect server with a external IP address already assigned?

Any ideas how this can be done on a ASA? There was a sonicwall in place but it just died and we do not have a replacement besides this ASA. The 24.172.x.132 is a spam filter and I can't change the ...
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Issue NATing server private interface to loopback (for MySQL)

I'm trying to NAT traffic sent to the server's private interface to the loopback (because MySQL bind-address is on 127.0.0.1 and can't be changed but I still need to reach it via the private ...
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kvm, can't access guest from outside host

following ubuntu guide on kvm, I've a test server up and running at this ip address 192.168.0.210 (netmask 255.255.255.0). The virtual machine (same as host ubuntu 11 server) use dhcp but has a ...
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SNAT through Racoon IPSec VPN

I am trying to route traffic from a device (that I will call "target") connected to my Ubuntu box (that I will call "host") to servers at a remote office. The host uses a Racoon IPSec VPN, connected ...
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How Does VPN Passthrough Actually Work?

I am interested in PPTP passthrough here not Ipsec etc. I have looked on the net but can't find out how it is done. I am an IT administrator myself and know a lot routing, NAT etc. I think I know how ...
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592 views

Assigning many WAN IPs to a Linux Router for 1:1 NAT?

I'm in the process of setting up an Ubuntu Linux box to act as a router. Its a fairly normal setup with NATing using IPTables - and its working fine for me. I'm about to put this into production, and ...
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Cisco Small Business: Classless routing vs Classful routing / Class A vs Class C?

Hypothetical topology: Cisco supports the diagram on the left as it relates to the Cisco Small Business WRVS4400N Router. As in, both sides of the WRVS4400N are 192.168.1.*, and the routing is ...