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

OpenVPN server cannot ping client (routing/iptables issue?)

I am not sure exactly where the issue is here. I'm fairly sure that this is some NAT or iptables issue on the OpenVPN server but am lacking the networking know-how to fix the issue. The crux of the ...
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1answer
62 views

Expose a machine on the far side of a VPN

We're using a VPN to connect a remote office to our main office, and a machine in the remote office needs to expose port 22 to the outside internet. Complications: The main office has a fixed IP ...
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29 views

Blindly bridging wireless client with MAC NAT

This is the usual "I want to bridge wifi with ethernet" question, but I need something specific here. My Linux box has a wlan0 interface which is in station mode, with MAC aa:aa:aa:aa:aa:aa, and a ...
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1answer
25 views

getting to server on internal network with the external address

I have a network behind a nat with exchange server. Mobile device are configured to access exchange using its real address (the single ip that the entire office hides behind) When the mobile device ...
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0answers
54 views

ASA 5515-X: Policy based NAT for dedicated uplink

We have bought a Cisco ASA 5515-X and we have the following scenario. Current situation: GigabitInterface 0/0, IP via DHCP, ISP1, Coax, 100M up / 12M down, medium latency GigabitInterface 0/1, ...
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1answer
32 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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29 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 ...
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1answer
52 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
29 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 ...
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1answer
195 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 ...
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3answers
128 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 ...
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1answer
62 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
872 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 ...
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1answer
83 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 ...
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2answers
608 views

Amazon EC2 VPC: NAT instance download speed performance drop

I have a set of servers inside Amazon EC2 in VPC. Inside this VPC I have a private subnet and a public subnet. In the public subnet I have set up a NAT machine on a t2.micro instance that basically ...
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2answers
99 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 ...
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1answer
40 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 ...
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2answers
503 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 ...
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1answer
89 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 ...
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1answer
255 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 ...
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1answer
228 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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2answers
216 views

Static public IP issue on Cisco ASA 5512x

This is our scenario: We have an Cisco ASA 5512x and we have 2 different Internet connections from different ISPs connected with it. ISP A is being used for the users browsing traffic(normal ...
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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
90 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 ...
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82 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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85 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
40 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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1answer
49 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
98 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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2answers
64 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 ...
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1answer
80 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
215 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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1answer
251 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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2answers
109 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 ...
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1answer
164 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
70 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 ...
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1answer
46 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 ...
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1answer
64 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 ...
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253 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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0answers
99 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
181 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 ...
2
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0answers
124 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
47 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. ...
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2answers
369 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
403 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 ...
2
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1answer
100 views

Stateless NAT with CentOS 6

I'm looking to set up the following: ---[IVR 1] | (internet)----[CentOS box]---+---[IVR 2] | ...
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0answers
51 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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44 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. ...
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0answers
144 views

Cisco 2901 Inbound NAT with local IP overload

Overview We are replacing a Juniper SSG on one of our networks with a Cisco 2901. Everything has so far been quite smooth except some issues have come up with external ports needing to be opened. ...
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156 views

Remote client (android) can't connect to OpenVPN sever behind LAN

My plan is to connect over tunnel (via Internet) android phone with my LAN at home. I set up OpenVPN server behind (router) lan (ip adress is 192.168.1.3). There is also my laptop. Port 1194 UDP on my ...