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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90 views

Forward web request to another computer

I have one notebook and two servers: ip = 172.17.0.2 (I have installed nginx here) ip = 172.17.0.3 (There is nothing here, but I can ping 172.17.0.2 from here) I open browser on my notebook, open ...
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1answer
74 views

How do I know that my TCP connection is safe from the Firewalls/NAT?

Being on the Azure cloud, I found that the firewalls there drop connections between the Web server and the database quite often. Mostly when there was some inactivity, I think something between 5 and ...
2
votes
2answers
134 views

Internet VPN Tunnel with a server behind NAT

Let's say someone would like to route all their traffic traffic though some PC in another country (to unblock some sites). However, this PC is a usual Windows 7 PC behind a router with NAT, which ...
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1answer
103 views

How to apply port forwarding with iptables on existing connections?

For load balancing purposes, occasionally our servers forward requests to a different port; The default port for our service is port 5000. This is the code used: iptables -t nat -A PREROUTING -p tcp ...
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1answer
121 views

Configure atftp server to reply on port 69

Problem : I'm facing to a problem with TFTP server and Cisco 79XX IP phones. When on a local network, everything is working fine, but when the TFTP server is on a public server (and phones inside a ...
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0answers
16 views

client does not respond server's syn_ack package

pc to access the server through a NAT device。 client has successfully established a tcp socket with server using this port , and the server's interacted with the message well, socket has been closed ...
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1answer
195 views

How can I know if NAT instance is becoming a bottleneck

I'm running my own NAT instance inside of an AWS VPC. I want to make sure that the NAT instance will not be a bottleneck and to that end would like to set my own expectation for when to scale to a ...
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0answers
110 views

Simulating a client behind a NAT in Virtual Box

I am trying to simulate a client behind a NAT using Virtual Box. I have a host machine let's say with an IP address 130.0.0.1. I create a virtual machine (let's call it VM1) running Ubuntu 12.04 with ...
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0answers
115 views

Load-balancing PPTP connections

I'm trying to load balance two PPTP connections, connected to the same server. I use the following script, but there is no send and receive via PPTP connections. What part am I doing wrong? Are there ...
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2answers
138 views

Iptables MASQUERADE: What is the advantage/disadvantage between these two commands? [closed]

What is the advantage/disadvantage between below 2 commands: iptables -t nat -A POSTROUTING -o eth0 -s 10.0.0.0/16 -j MASQUERADE AND iptables -t nat -A POSTROUTING -j MASQUERADE Some Background ...
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1answer
178 views

iptables DNAT port forward to another machine on LAN

I am trying to implement iptables forwarding rules in order to internally redirect packets coming through a specific port. My machine is running under the distribution Ubuntu Server 12.04.3, with UFW ...
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2answers
1k views

AWS VPC + IPtables + NAT: Port Forwarding is not working

Yesterday, I posted a question here but I think was not clear enough in my words. BTW, This question is not a duplicate. I have AWS VPC Setup as below. GOAL/PROBLEM: SSH to Server A from internet. ...
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2answers
70 views

IPtables: Forward port to another host is not working

I am trying out something so this is my test setup: Setup: I have AWS VPC with a public and private subnet. I have a host in public subnet with a public IP address (say Host A) I have a host in ...
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0answers
286 views

Asterisk: Retransmitting again and again

I have following sip settings Name : external Description : Realtime peer: No Secret : <Set> MD5Secret : <Not set> Remote Secret: <Not set> Context : public ...
0
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1answer
138 views

IPTables and SNAT for just two ports

I want to set up some NAT policies so that certain machines will only have outbound access to http/https. They should not be able to do port scans or anything else from their machine. Currently my ...
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0answers
149 views

Repair RRAS and NAT on Windows Server 2008 R2

We have a Windows Server 2008 R2 server with RRAS installed and configure with VPN and NAT. NAT stopped working and when I checked, IPv4 is missing . I've tried re-installing RRAS but it just ...
0
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1answer
33 views

Can't see Webserver from LAN - NAT Issue?

I just got a ZyXEL USG50 and it's more complex than I'm used to. Traffic from WAN is going to my websever as desired thanks to a firewall and NAT rule. The problem is, when trying to request a ...
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1answer
3k views

Cisco ASA 5505 - NAT or Port Forward for SIP / VoIP ver 8.4

I just had an NEC PBX installed that lets me use SIP trunks for VoIP services, My gateway is a Cisco ASA 5505 running 8.4 and I only have one public/static IP Addresses. So far, my trunks are ...
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1answer
241 views

Apache2 server (behind Zyxel USG 100 NAT/Firewall) with vhost does not log real clients ip addresses

SOLVED To allow the Zyxel USG 100's NAT to forward untouched packets to my web server i edited the policy route of the Zyxel. Zyxel -> Configuration -> Network ->Routing -> Policy Route ...
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0answers
81 views

Port corruption using iptables NAT on Enterprise Linux 6

I am trying to setup a captive web portal redirect on CentOS using the following configuration: This configuration works for the first few packets, but then suddenly the destination port is corrupted ...
2
votes
1answer
730 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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2answers
33 views

IIS and Apache hosting together

I know similar questions have been asked already, but mines a little more unique. I work for an internet/networking company. We build and host websites, as well as provide internet and network setups ...
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2answers
79 views

INPUT, OUTPUT or Forward Chain

I'm using a linux box as a router: The Box has 2 public ips and local ip, i'm using natting to allow local users to access the web. When a local user access the web, source natting happens here, ...
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votes
1answer
163 views

iptables and port redirection (nat)

I am trying to build a router from ubuntu 12.04. What I am trying to do is, by using 1 public IP (100.0.0.100) and I tons of local ips like 10.0.0.0/16, to map each port to one ip like; ...
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1answer
141 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. ...
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2answers
236 views

Accept incoming connection from a second gateway

I searched a lot about the question, but can't find solution for my situation. We've got a Windows 2003 server that runs Advantage Database Server (ADS) through which our site connects to our ...
2
votes
1answer
199 views

Redirection with natd flags on FreeBSD

I am trying to setup a basic NAT server. I want all traffic coming from the outside world to the NAT server to be redirected to another machine, where I have a lipcap service running to parse this ...
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0answers
85 views

How to set mark on packet when forwarding it in nat prerouting table with rp filter 0?

I have a serious problem with my server ubuntu 13. I have two ADSL lines and an internal network as follows. i.imgur.com/v4ddHXf.png (URL IMG) IP redirections made ​​two because there are two older ...
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2answers
188 views

NAT vs Proxy server

I have installed squid proxy server to hide our network ips after some time it becomes slow then I read through NAT rules to achieve what I want by proxy server. As per this link the difference ...
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2answers
162 views

Router/Gateway with host-header capability

Can anyone direct me what to look for to get a Router / Gateway / Firewall for my home-office enviroment to be able to run multiple e.g. Webserver on port 80, with one public ip. I know it can be done ...
0
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1answer
124 views

iptables alternative for nat in windows

When setting up a comms server I usually use iptables in linux to forward any incoming connections on a particular port to another server, e.g. Chain PREROUTING (policy ACCEPT) target prot opt ...
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0answers
65 views

Multiple routes and gateways with NAT

My setup is a VM host with two network interfaces where I want to use one as private/internal and the other one as public (which will get a public address on the host), where all the NAT magic to the ...
1
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1answer
469 views

iptables port forwarding to vmware workstation guests on NAT vmnet [closed]

Try as I might, I can't get this to work now for 2 days. Your move, internet. I want iptables to transparently forward (localhost) 192.168.1.40:2222 to 192.168.2.22:22 and I don't want ...
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votes
1answer
65 views

Cisco ASA 5505: Created a faulty NAT rule. Can't reach the ASA

I was trying to create a NAT rule to reach my internal web server from inside the LAN. Something must have gone wrong. Now when i try to reach the ASA through https://192.168.1.1 the response is from ...
2
votes
2answers
81 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 ...
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2answers
192 views

VMWare NAT releasing SYN packets from guest but not admitting SYN/ACK packets to guest

VMWare Server 2.0.2 Host OS is Windows Server 2008 R2 Standard Guest OS is Windows XP I am using VMWare VMNet8, the NAT network. The VM guests can't see out to the network around the VM host. Packet ...
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0answers
45 views

CISCO IOS Forward (nat) specific IP to other IP and Port

I've a customer that has a CISCO 7604 as a Border Router.. (Within Network uses Mikrotik, Freeradius, Meraki, etc)... I'm trying (newbie with Cisco) to create a Forward Rule (in Mikrotik is a Nat ...
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votes
1answer
204 views

Ubuntu Server / IpTables / Port Forwarding / NAT

I got referred here from StackOverflow. I'm using IpTables to forward an incoming port on one server to an external server (not on LAN) and the same port. The problem I'm having is that I have to use ...
2
votes
0answers
131 views

Keepalived failover not working for Static NAT target behind Cisco ASA

I've got a Cisco ASA[0] with a pair of Linux boxes in the DMZ running Keepalived and HAproxy acting as a load-balancing failover pair for another pair of Windows servers, also in the DMZ. I'm ...
1
vote
2answers
793 views

How to configure and enable NAT with server core installation

Using Microsoft Server 2012 Core: What is the equivalent core/Powershell command to enable and configure NAT. I have configured NAT on servers with the following GUI steps: Server Manager, Tools, ...
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votes
3answers
185 views

CentOS masqueraded network with iptables clients not connecting: Unable to ping

I'm a novice sysadmin working on a system with a CentOS server masquerading traffic with client machines also running CentOS. Something with the tables got messed up and my clients no longer have ...
0
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0answers
28 views

SonicWall VLAN Device Redirection

I have a device (Network Attached TV tuner) I use on my X0 VLAN. I have a wireless (W0) device that I would like to be able to access this device on my VLAN. The problem is right now the devices ...
0
votes
1answer
109 views

How to bind traffic of each NAT client to a external IP address?

I have a NAT router with 2 IP addresses, lets say 111.111.111.111 and 222.222.222.222 associated with the interfaces eth0 and eth0:1 respectively. I have two servers that connect to this NAT gateway ...
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0answers
57 views

Cisco ASA ASDM Missing Nat options when creating network object

Hello all hope this is a simple fix. In ASDM of one of our ASA's, when we go to create network object. the NAT options to create automatic NAT rule is completely missing. its just a small box to ...
2
votes
1answer
379 views

Dual ISP Inbound NAT — Asymmetric routing

routing question here. In a dual ISP scenario is there way to use both external IPs and nat them to a web server in a higher security level? The issue I am running into is on the return path for ...
0
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0answers
195 views

Martian packet errors with physical adapter's IP address on GRE tunnel

I'm very new to the networking world (most of my time is spent as a developer), so I could very well be missing something simple. TL;DR version: I get 'martian packet' errors on response traffic when ...
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2answers
67 views

Connect four Modems having same IP with a single Ethernet Switch [closed]

I have a scenario where i have 4 modems connected to a switch. all four modems have IP address 192.168.0.1(default). i want to connect all of these four modems with a single switch in a way that i ...
0
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0answers
180 views

Multiple virtual interfaces with multiple openvpn interfaces

I currently have 4 interfaces with static IP addresses from the local network; eth0:0 eth0:1 eth0:2 eth0:3 I also have 4 OpenVPN TUN interfaces which are connected to various servers around the ...
4
votes
1answer
1k views

How do you NAT Hairpin in IOS 8.3+

As I asked here and duplicated here it appears NAT Hairpinning is the answer I'm looking for to allow internal servers to loopback through the ASA to access external IP's (without using DNS ...
1
vote
1answer
359 views

pfsense nat between two internal ip

TL;DR What technology should I use to translate an internal address (192.168.1.10) to another internal address (192.168.1.11)? So that when I access the first I get redirected to the other? Long ...