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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42 views

Why Use a NAT Instance? [closed]

Consider the following VPC: Public subnet with app servers and a separate NAT instance. Private subnet with database server. What benefits do we gain by using a stand alone NAT? EDIT: Why use ...
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1answer
124 views

Force Cisco ASA to change source port NAT

I have a 2 devices, a Cisco ASA and sitting behind it another device. Both the Cisco and the other device have IPsec tunnels but to different locations. I need to ensure that the source port of the ...
3
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3answers
21k views

Passive mode for FileZilla FTP isn't working

We have FileZilla server 0.9.37 running on Windows server 2008 R2 Active mode works OK, The Windows firewall on the server is off. Our Router is a DrayTek vigor 2820. Under NAT, Open Ports, I have ...
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0answers
34 views

Routing and RAS with multiplice public IP-Adresses

I have two public ips, e.g. (1) = 111.111.111.1111 and (2) = 222.222.222.222 on one NIC of a Windows Server 2012 R2 Server. I'm using "Routing and RAS" to forward some ports by NAT rules to Hyper-V ...
1
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1answer
242 views

Apache presents wrong certificate when accessed via load balancer [duplicate]

I've got a server that has two SSL certificates set up, one for internal access where it is accessed along the lines of host.my-local.net and other for external access where it is accessed similar to ...
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2answers
31 views

Could I have 2 nat on vpc [closed]

There is a vpc on amazon that has two subnets. The outer one has internet access and the inner one using NAT server to connect to internet. Inner subnet have plenty of servers for development and ...
3
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1answer
541 views

Internet access from private VPC subnet?

My brain is a little bit fried trying to figure this out but I can't seem to get private subnets to connect to the internet to grab updates for example. Basically all I want is web access for these ...
1
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3answers
185 views

Forward Traffic in & out, NAT iptables

I have a box setup as DHCP Server with NAT ipv4 forwarding enabled. Currently the box uses eth0 to connect to a local network and has access to the internet, it has another 3 interfaces, eth1, eth2 ...
2
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2answers
2k views

OpenWRT Barrier Breaker - Router does not route

I've upgraded my TP-Link 1043 router to OpenWrt 14.07. Everything is perfect, Wifi and LAN are bridged, LAN machines can access each other by name, I can SSH into the router, and the router can access ...
0
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1answer
82 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 ...
0
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2answers
179 views

How to redirect a packet with iptables that match a certain pattern? (eg a QUERY command with UDP)

I have a certain packet that I want at all times to be redirected to a specific ip on my virtual network interface. As for now my iptables is setup like this: (the commands, I use \ as for now to ...
0
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1answer
53 views

How to route an IP Whitelist to one VM and all other to a second VM on proxmox?

Is it possible on linux to have a whitelist of IP's that are allowed to reach a specific VM on the internal NAT? eg (public ip (proxmox) --> My VM for whitelisted IP's (192.168.0.1)), and if the ...
2
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2answers
1k views

Make CentOS 7.x a port forwarding NAT device

I would like to make CentOS a port forwarding NAT machine using iptables. This is the first time I've tried this and I think i might need a little help. This is the configuration i'm trying to ...
1
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1answer
541 views

My iptable rules do not allow VPN connections

I have installed OpenVPN on my Archlinux server and modified my iptable rules to allow incoming traffic on port 1194 and forward it to the tun0 interface. When I disable/stop the iptables, the OpenVPN ...
1
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1answer
318 views

AWS EC2 Ubuntu 14.04 Instance smtp port forwarding from 25 to 2025

I am trying to step up port forwarding from port 25 to port 2025 on the same AWS EC2 Ubuntu 14.04 instance using iptables. I am using port 2025 to receive income emails using Alfresco. The first step ...
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1answer
125 views

Are iptables prerouting (DNAT) packet changes visible to subsequent chains?

I was reading Rusty Russell's NAT Howto when I came across this section: 6.2. Destination NAT This is done in the PREROUTING chain, just as the packet comes in; this means that anything else on ...
2
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1answer
3k views

Routing between 2 different subnets on 2 different interfaces in SonicOS

I'm having a bit of a problem allowing traffic between two of my subnets. Here's the structure I've built. The X0 interface has our windows server on it and it handles DHCP/DNS, etc. X1 has the WAN ...
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3answers
4k views

Reloading NAT configuration on a running VMWare Server 2.0.2

I have a server running VMWare Server 2.0.2. The host is Debian Lenny. I have 15-20 virtual machines running, all attached to a single NAT network (named vmnet8). I have configured VMWare's NAT (the ...
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0answers
11 views

iptables NAT can't initialise on Debian openvz [duplicate]

So i want to create a nat rule for an openVPN server. After getting trouble with the TAP/TUN Devices, it's finally working i think It's working greate but not routed so useless. Now i have to make a ...
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1answer
146 views

Forward incoming packets from port 25565 to natted internal client? IPTables [closed]

I have been learning to use iptables recently and i made a small nat network in virtualbox. I have a Debian server Natting for the internal clients. One of the internal clients is hosting a minecraft ...
0
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0answers
94 views

Ubuntu as IPSec L2TP client with NAT traversal

Goog afternoon, I have a corporate local network located behind NAT. There is another NAT in this local network for the corprorate server on Ubunit 12.04. So if clients connect to that server ...
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0answers
104 views

SFTP Reverse-Proxy using iptables on custom port

I want to give SFTP access to anyone into to my Server (IP: ss.ss.ss.ss) passing through Proxy (reverse-Proxy? IP: pp.pp.pp.pp), so that IP ss.ss.ss.ss is never seen by whoever is connecting to the ...
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0answers
51 views

Access servers from both side without hairpin router

We have a router that does not support hairpin NAT so our app server is not able to be accessed from inside. When using mobile devices we have to either change the app settings or computer host file, ...
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0answers
316 views

Accessing public ip from within freebsd jail with ipf and ipnat

I'm using FreeBSD 9.3 (same issue with 9.2 and 10.0 in test VMs). I have jails running on lo1 10.0.0.x addresses. I use ipf with this config in /etc/ipf.rules: pass in quick on em0 all pass out quick ...
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1answer
445 views

Proxmox VE: Multiple shared public IPs with NAT configuration

I have a Proxmox VE (v3.3 @ Debian 7 Wheezy) and got 3 public IPs routed to that server. It is my aim to have multiple VMs sharing those IPs using a NAT configuration so that I can forward single ...
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1answer
97 views

How to start with IPv6 subnetting on linux gateway

We are currently having perfectly working IPv4 network with a typical layout - internal network with all servers splitted to VLANs in 10.0.0.0/8 (each vlan is /24) and external network with public ip ...
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1answer
58 views

Can I use an external IP to make 2 internal IP's establish a TCP/UDP connection? [closed]

As I understood, in order to make a connection to an internal IP (behind NAT), the computer behind the internal IP have to send the request first before the other side will be able to answer it, So if ...
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0answers
122 views

iptables - dropping specific established connections after X hours

Is there a way with iptables to drop specific established connections after X hours? We have an application with limited connection support, and occasionally we see some tcp sessions that shouldn't ...
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1answer
331 views

How to trace dropped TCP connections?

Trying to help someone with a situation where TCP connections get mysteriously dropped after a few minutes for no apparent reason (this happens even with non idle connections). Both client and server ...
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2answers
65 views

Is it a security improvement to use NATed network?

There is a website that blocked an ISP's subnet (because attacks came from that network). The ISP gives it's users only NAT'ed IP addresses, so the clients are geting 10.x.x.x IP addresses on their ...
2
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0answers
558 views

Connectivity issues with dual NIC machine in EC2

I'm trying to get some servers set up in EC2 in a Virtual Private Cloud. To do this, I have two subnets: 10.0.42.0/24 - Public subnet 10.0.83.0/24 - Private subnet To bridge these two, I have a ...
0
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2answers
121 views

Forwarding HTTPs requests to another webserver

I have an Ubuntu 12.04 Server connected to two subnets. Eth0 is 20.20.20.1, it hosts an Apache Web Server on port 80. Eth1 is dynamic IP address in 10.10.10.0 subnet. This server is not a gateway ...
0
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1answer
697 views

Cisco 887VA Port Forwarding Not Working

I have a Cisco 887VA connected to our BT Business Broadband line. We also have another modem on a seperate connection which also handles our DHCP. The Cisco is plugged into our network switch, as is ...
2
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1answer
171 views

website not accessible with IIS6 while NAT is configured in Windows 2003

I have Windows2003 server configured with IIS 6. Until now it was working fine, but since I enabled NAT for my users to access the internet via this server, the website becomes unavailable. Note that ...
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1answer
458 views

Can't set up the default route from a sublan to the WAN [closed]

I am trying to connect one of my PCs to the Internet via a WiFi network using a notebook. Here is my network : (Wifi) <=============> (Notebook) <===============> (Desktop) ...
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1answer
93 views

iptables with sticky forwarding/routing

My iptables is sticking. I have a DNS server behind IPTables and down a NAT'ed OpenVPN pipe. Using tcpdump I see DNS packets hit the outside router but it takes 4 or 5 DNS query attempts before the ...
0
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3answers
1k views

Using a nat rule to translate 80/443 traffic to web server, but internal users cannot access it using external ip/domain name

I am using Cisco ASDM for ASA I have my internal network called soa. My outside interface is called outside. Let's say my outside IP given to me by my ISP isp is y.y.y.y I have a web server inside ...
0
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1answer
52 views

Keep source port for outgoing packets

I have 2 interfaces eth0(192.168.0.1) and eth1(10.1.1.15). And I do nat for all packets in this way. iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -j MASQUERADE Now I want to keep source port ...
0
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1answer
122 views

Proxmox with iptables nat is not available

I got an issue with iptables on my virtual machines. I installed proxmox 3.1-21 on my rootserver. I have around 6 IPs linked to my rootserver so i created new 'CT's. The problem is i need to ...
2
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0answers
147 views

Apache Instance in Private Subnet not returning packets

How can we get the Apache instance in a private subnet to work? Configuration Public subnet with 1 NAT instance Private subnet with 1 App instance Details 1. Masquerading is turned on NAT on via ...
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0answers
156 views

Debian forward through NAT EOIP GRE

eth0 = WAN eth1 = LAN to forward any port through nat I use e.g: iptables -t nat -A PREROUTING -p tcp -d 79.188.31.34 --dport 8291 -j DNAT --to-destination 192.168.0.36:8291 and it works, but ...
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0answers
200 views

Linux router with multiple gateways and port forwarding

I want to use a Linux VM to act as several routers at once. I have multiple servers hosting different services and dedicated public IP for each of them. Super simplified setup example: Ubuntu ...
5
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1answer
787 views

Windows Server 2003 IPSec Tunnel Connected, But Not Working (Possibly NAT/RRAS Related)

Configuration I have setup a "raw" IPSec tunnel between a Windows Server 2003 (SBS) machine and a Netgear FVG318 according to the instructions in Microsoft KB816514. The configuration is as follows ...
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69 views

Should a NAT host be separate from a Bastion host

Have a private network with servers that required SSH access. Since the instances are in a private subnet, they cannot be accessed directly via SSH and require a public Bastion host to access. ...
2
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1answer
4k views

How to Configure Source NAT (Private IP => Public IP Outbound)

I'm running VMWare ESXi Free and have Zentyal SBS 3.2 running as a Gateway. I have 5 Public IPS (CIDR/29, let's call them 69.1.1.1 - 69.1.1.5) and currently Zentyal is bound to 69.1.1.1 as the ...
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2answers
698 views

Using Router with DHCP and NAT and Windows Server 2012 as DNS

I have a network currently set up as per the image below. We use Regus's shared Internet and I've create a sub network for our office by using DHCP and NAT on the airport extreme router. Now the ...
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1answer
1k views

openwrt dmz nat loopback not working

I would like to have my "dmz"-connected visitors to be able to access services by their global DNS IP (wan) that are redirected to another zone, let's say "lan". openwrt wan - 12.23.34.45 client is ...
0
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1answer
705 views

Port forwarding with iptables -> connection refused

I am trying to redirect requests to my local IP (10.42.42.152) on port 80 to a remote server, e.g. google.com (173.194.113.104:80). The remote server is up, ip_forward is enabled but I only get ...
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0answers
68 views

tun0 not listening traffic on a simple vpn example

I tried to setup a simple vpn test server on Ubuntu 12.04, called ToyVPNServer. The guide is simple and I take test for days but still cannot get connected. The inspection result is showing the issue ...
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56 views

SRP521W Intervlan routing and NAT

I've a Cisco SRP521W router which I've set up with two VLANs called normal_Lan and SWSVLAN. I don't want devices on each VLAN to communicate with each other so I've turned INTERVLAN Routing OFF. ...