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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Using DNAT with IPtables

I am trying to figure out a DNAT issue and I am hoping I can get a hand. Basically I have a OpenVZ box that connects to my LAN via the SoftEther Client. What I am trying to accomplish is a way to ...
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109 views

Cisco ASA - Allowing external access to a secure server via RDP

I am new to the forums and really hope someone can help me. I am pulling my hair out! I have posted on both the Cisco forums and Windows forums in hopes anyone can suggest something but no one has ...
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2answers
238 views

How does Pinging from a private IP behind NAT to a public IP work

Recently I realized that ICMP does not contain any ports, so I tried to Ping from my wireless connected laptop to public IPs(of course it worked!). In a typical configuration, a local network ...
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40 views

Couchbase XDCR through proxy or NAT

I am trying to set up two clusters of Couchbase with XDCR, one in AWS and one in our client's enterprise network. Normally, for each cluster, I would set up each node using its private IP. But, in ...
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1answer
47 views

How to mimic “DMZ Host” or “Default Host” NAT funcionality with iptables?

My previous DSL modem had a function called "DMZ Host" (which in other platforms seems to be named Default Host). When you select a computer in your network to be the DMZ Host, it forwards every non-...
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2answers
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How can I DNAT a packet coming through a bridge back to its source with iptables? [duplicate]

I have a host1 that has a WAN interface eth0 (1.2.3.4) and a LAN interface eth1 (10.41.82.1). Inside the LAN is a host2 with the IP address 10.41.82.2. Incoming connections to 1.2.3.4:22 are ...
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50 views

AWS NAT instance as OpenVPN Client can't route instances behind it

I have an Amazon AMI 2015.09 instance as a NAT server for my backend servers. I have configured the OpenVPN client on this same box, the NAT server is able to talk to everything over VPN, all ...
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23 views

Linux Iptables Nat with two gateway

I got a CentOS server in a DMZ that act as a DHCP and DNS server with the following network configuration: eth0 IP: 192.168.100.50 SN: 255.255.255.0 GW: 192.168.100.1 Now I added a seconde network ...
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1answer
87 views

When I ping local IP address I get a reply from external IP

I have SonicWall NSA 2400. Port X2 is WAN port with following settings X.X.X.250 / 255.255.255.248. I connected VPN concentrator to port X5, which is assigned to DMZ zone in Transporarent IP Mode for ...
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2answers
4k views

Adding multiple A records for same host for backup purpose

I have a webserver. I have 2 static IP's from 2 different ISP's. I want to make sure my webserver is accessible when one ISP's network(s) are down. for example my host name a.example.com my ISP1 IP ...
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1answer
27k 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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86 views

Assign WAN IP on internal NAT network

I have a static WAN IP address (in the example 77.88.99.166) that is provided by a DSL modem that also has a static IP address (77.88.99.165). The modem interfaces with a firewall/NAT router (green) ...
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25 views

Direct native traffic TCP file transfer between two NATted machines

Aim: I want to perform the fastest possible TCP based file transfer between two machines sitting behind two different NATs, in a situation where a public port cannot be redirected to any of the two ...
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17 views

One-to-One NAT with Firehol

I use firehol to manage iptables on Ubuntu 12.04. I am trying to set up one-to-one NAT so requests from the internet and my LAN to one of my public IP addresses goes to a specific server. Here is what ...
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2answers
47 views

How to route requests through router based on domain names?

Assuming a setup as seen below, is it possible to route requests for e.g. subdomain1.domain.com to Server 1, subdomain2.domain.com to Server 2, another seconddomain.com to Server 2 etc. without ...
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2answers
105 views

How to connect a client behind a NAT router to an Asterisk server behind a NAT router?

I have an asterisk setup on a server. The local IP address is 172.22.9.200 and extenal IP address is 75.45.185.100. My client device is an android phone that is connected to a router and it which ...
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3answers
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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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1answer
130 views

How to get around Double NAT from the ISP?

I have a client located in a rural area where they are using the ISP Xplornet, it's a wireless/satellite type of internet connection. After initial setup, We where able to have access to the site ...
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32 views

NAT failed when DirectAccess Enabled

I have this topology: I have 192.168.1.0/24 as private network, 20.1.1.0/24 and 100.1.1.0/24 as Public Network. WinDC is the Domain Controller and Winrtr is Router. The ISP act as outside DNS and ...
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0answers
17 views

Iptables vm no outbound connections

I'm currently running Proxmox with a couple of vms. Unfortunatly i only got 1 public ip so i tried to work with nat. Problem is, i can't get outbound connection from my vms. Inbount connections to the ...
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1answer
89 views

Setting up Amazon elastic beanstalk to be accessible through fixed ip address(not CNAME)

I want to deploy my app to multi-container elastic beanstalk to be able to point my A-record to some fixed ip connected to it(somehow). I've read related questions(like this one) and understand that ...
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113 views

TCP RST/ACK packets not being sent back to NAT client with Forefront TMG

With Forefront TMG, we have an issue where all TCP connections to allowed ports work just fine when the connection is accepted with SYN/ACK, but when they are rejected with RST/ACK, the response does ...
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12 views

iptables avoiding chain's rules on nat table

I have lots of SNAT rules on HTTP (port destination 80) traffic in my POSTROUTING chain of the nat table. I'm trying to reduce the processing cost by adding a rule that filters out the non-HTTP ...
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1answer
64 views

VoIP: No audio, local IP in SIP header

I'm trying to get SIP trunking to work on my Bintec Elmeg hybird 130j with sipgate.de as trunking Provider. So far, call signalisation works fine, so I can call outside phones and also get called ...
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1answer
114 views

Amazon Linux - iptables NAT rules not matching GRE traffic

I'm trying to prototype something in AWS VPC/EC2, but I can't get my NAT rules to work. I have the following setup (all instances running the Amazon Linux AMI): GRE Tunnel between instances 10.0.0....
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1answer
9k views

Port Forwarding on Cisco Router

I'm a Cisco newbie, have the 1841, with two ethernet interfaces: interface FastEthernet0/0: Internal Desired destination IP: 186.67.181.140 interface FastEthernet0/1: External World IP 186.67.181....
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26 views

Not getting TCP Update Window packet after TCP Zero Window begins

Once I get TCP Zero Window during data transmission, I can't send data anymore in that desktop sharing session. Even I stopped the data sending to check if it can resume but no benefit! In my test ...
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9answers
3k views

How common is NAT within companies (one public ip address)?

How common is for companies to let many users share only one public ip address? I hope the answer is "not very common" since I'm developing software that depends on the ip number being pretty much ...
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2answers
38 views

Iptables NAT (PAT) A to B to C and back

I want to access via SSH a DB server from an outside network via a linux (CentOS) gateway with two interfaces in separate networks as it follow below: Admin PC IP: 10.21.1.8 Linux GW IP eth1 ...
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1answer
46 views

Azure NAT blocking connections

When I try to connect to a port on the public IP address of a node, 50% of the time Azure doesn't respond and nmap marks it as "filtered". When I try to connect to the same port from the node using ...
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1answer
91 views

ProFTPD IP masquerade just some ways

I am trying to setup a FTP server using ProFTPD on Xubuntu 15.10. Users will connect to this server in two ways: internally (using an internal IPv4 address) externally (using domain name pointed to ...
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1answer
74 views

Cannot SSH to ec2 instance in VPC

I'm just starting with AWS, and have 2 ec2 instances running on a VPC, one with a public and private IP, one with only a private IP. I can SSH to both (using my key) if I attach an external IP to ...
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30 views

Translating DNS Server Replys because of multiple NAT Networks

I am planning and building a large infrastructure wich different natted networks. Lets say I have a datacenter network 10.0.0.0/24 and I have many different customer networks that could be anything (...
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151 views

Routing public IP addresses to customers in a WISP setup

We have a fibre leaseline with a /29 range for our pfSense WAN port 61.179.145.40/29 So the WAN of our pfSense box is 61.179.145.42 with a gateway of 61.179.145.41. Our ISP has also routed 61.179....
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697 views

set mark on iptables based on interface

I have an Ubuntu 10.04 machine with two ethernet interfaces: eth0 (WAN) eth1 (LAN) I've configured NAT using these commands: sudo iptables -A FORWARD -o eth0 -i eth1 -s 192.168.0.0/24 -m conntrack --...
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3answers
4k 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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2answers
787 views

Trying to connect to servers in a remote lan with softether vpn client and iptables nat ip_forwarding

I have implemented a softether vpn server on one aws server connected to other instances in a LAN. I can ssh into the server with ssh myname@10.0.1.10 without problem. I followed this guide My goal ...
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1answer
72 views

DHCP Server with 2 nics

I have windows 2008 r2 x64 enterprise server with a domain. That server has 2 NIC nic1 which is connected to a router nic2 - here i need 1) run dhcp for private LAN 2) forward internet connection ...
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26 views

Redirect external ip of server to external ip of virtual machine

I have a server with multiple virtual machines. Let's say this is my server ips: Internal 1.2.3.4 External 5.6.7.8 Now, if i go to 1.2.3.4:8082 it goes to my app (I redirect :8082 to de internal ip ...
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0answers
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Reverse proxy, NAT on port 80 and problems to surf web [duplicate]

We have 1 public IP adderss, and some applications that we want to be available outside. I setupped NGINX as a reverse proxy and it worked very well. It's the same IP and port, but the traffic is ...
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4answers
32k views

Forwarding ports to guests in libvirt / KVM

How can I forward ports on a server running libvirt/KVM to specified ports on VM's, when using NAT? For example, the host has a public IP of 1.2.3.4. I want to forward port 80 to 10.0.0.1 and port 22 ...
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1answer
32 views

IP NAT from router to SSL-VPN appliance

Has anyone use Cisco 891-K9 to forward 443/SSL to a SSL VPN appliance? (I've never encountered this situation before because either the public facing router terminated VPN directly or we had multiple ...
29
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8answers
23k views

Loopback to forwarded Public IP address from local network - Hairpin NAT

This is a Canonical Question about Hairpin NAT (Loopback NAT). The generic form of this question is: We have a network with clients, a server, and a NAT Router. There is port forwarding on the ...
2
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1answer
69 views

AWS Close Ports on Specific Elastic IP Addresses for EC2 Instance

I have a Windows Server in AWS EC2. I have opened ports 80 and 443 to 0.0.0.0/0, and RDP to a private IP address for VPN access. The instance has 4 total elastic IP addresses, each mapping to a ...
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1answer
984 views

Cisco 1841 - Configuration Issue with NAT

We recently dug out an old Cisco 1841 to solve a need and have been in the process of trying to configure it appropriately. Admittedly, this is my first escapade into the land of Cisco Routing. I've ...
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33 views

VPN with VMware Player [closed]

I have 2 domains, prod and dev. Dev has a 1 way trust from prod (dev trusts prod, but prod does not trust dev). My host computer (laptop, win7 sp1) is a member of the prod domain and can VPN in for ...
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1answer
38 views

nat and xen, nat only to external ip

I've setup xen that way that all my vm's have a public ip and a private ip (192.168.0.x). However, those vms which don't have a puplic ip should also get internet access so I did setup nat. iptables ...
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2answers
142 views

How can I use NAT or haproxy to reroute a certain host name?

I have an infrastructure where all requests made by internal subnets have to pass through a server in the "open to the world" subnet, where my NAT instance is (I'm using AWS). I want to create a host ...
1
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2answers
262 views

Cisco static NAT not working on LAN side

I have a web server in my private network that has the ip address 192.168.1.134. I need to allow users to access this web server from both the internet and the private network. The public ip address ...
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2answers
1k views

Windows Server 2008 dropping connections [closed]

Possible quite similar to this post but I wonder if someone can help me with this issue. Home Server specs: Windows Server 2008 Standard (Non-R2) 2 NICs, external one(Realtek) has a firewall on it. ...