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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DD-WRT: Remote SSH access doesn't work when OpenVPN client is enabled

Problem description I have a DD-WRT router which I would like access remotely via SSH. The DD-WRT is behind an ADSL router which has port forwarding for port 22 enabled, DD-WRT SSH access and service ...
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1answer
63 views

Which SSL certificate would I need for external AND internal domain names?

This is a school-network. Official (outside reachable domain name) is bgschwechat.ac.at (www.bgschwechat..., mail.bgschwechat... and ftp.bgschwechat..) Internally the windows domain is named ...
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8 views

L2TP daemon server multiple IP

I have VPS with 3 public IP - Debian 7. I would like to have 3 L2TP damemons (one ip each) NATing traffic to each ip. Something like this l2tp_multiple_public_ip_diagram. I have set up l2tp daemon for ...
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2answers
32 views

NAT-ing with iptables rewrites source IP in logs

I have the following infrastructure in place: internet [outside 81.x.x.x] router [inside 192.168.1.1] | [network 192.168.1.0/24] ...
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2answers
65 views

router: ping fails at specific time for 40 seconds

my network looks like this: ISP cable --- ISP modem/router (2 in 1) \ \--- my router --- wifi connection --- computer 1 \----------- cable connection ...
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0answers
18 views

iptables, outside and inside NAT; Return traffic going out incorrect gateway

Overview (TL;DR at bottom) I have a third party firewall/proxy appliance which is running Linux (Ubuntu), and its routing and firewall engine is backed by iptables and the Linux (source)routing ...
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5 views

vagrant guest connection problems [migrated]

I have VirtualBox 4.3.22 on OSX 10 with guest additions installed In VirtualBox I have: Vagrant/CoreOS guest vm in NAT networking mode with eth1 addr 172.17.8.101 Ubuntu 14.04LTS guest vm in ...
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27 views

Windows Server as a PPTP Gateway

I have a Windows Server 2012 server at work, which is currently used as a domain controller, and an internet gateway. The current internet connection uses a USB dongle, which appears like a standard ...
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30 views

FortiGate 310B public ip pool into internal port

I have a FortiGate 310B with WAN port with /27 public IP pool from the ISP. The WAN port is configured with primary IP 1.1.1.1/27 I would like to provide servers within the Internal port a public IP. ...
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21 views

Cisco ASA firewall blocking requests to internally hosted DNS server

I have a DNS server behind a Cisco ASA firewall. The Cisco firewall is performing NAT. When inside the network, I can NSLOOKUP directly to the server. When the client is external, requests time out. ...
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2answers
30 views

Reaching Local Network which is under NAT with no public IP

I have a place called (lets say) REMOTE. REMOTE is connected to the Internet using 3G/4G Modem + Router. Unfortunately my mobile Internet provider does not give me public IP address. In REMOTE I have ...
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27 views

IPTABLES forwarding [duplicate]

I`m trying to forward all traffic to remote server to local port e.g. if i try to connect to 10.0.3.43:5901 it should forward me to localhost:10000. I created two rules in iptables ...
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18 views

NAT and S2S VPN to Azure issue

I can connect to the VNet with on-premise WS2012 R2 RRAS S2S VPN connection successfully. The on-premise WS2012 R2 has two NICs, "External" and "Internal". "External" NIC is facing to a public IP ...
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15 views

NAT and DMZ Cisco ASR 1001

OHAI got weird situation on my two Cisco ASR 1001. First one is WAN router, the other one is CORE distribution inside the office. So I've got one public IP on my WAN, and got this particular line: ...
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3 views

OpenVPN sans port forwarding on unfriendly networks [migrated]

I have a problem. I'm about to move onto campus right in the middle of the semester. For a student, I have a complicated network setup where all of my systems are reliant on NAS and all of them VPN ...
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34 views

Change source IP for packet incoming in VPN tunnel

The following configuration allows me to change the source IP from 192.168.0.0/24 to 172.16.0.100 when hosts going to 10.0.0.100 and it works. But I can't achieve this goal for the hosts incoming from ...
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1answer
35 views

Cisco IOS - Problems with NAT and port forwarding

I have a problem forwarding ports. I have configured a NAT pool of 1 address (192.168.5.2) and assigned that address to the WAN interface. I assigned networks to the access-list, and bind the two ...
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8 views

PPPoE server NAT

I configured cisco router as pppoe server and my clients are PC's, the problem is NAT working so the client cannot ping other routers i had to static route the client pool on these router, any ideas ...
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1answer
37 views

Forwarding a port on the loopback interface to a remote IP/port

I have two Docker containers that I'm trying to network together in a specific way. Container A is running a Redis server on port 6379. Container B is running an interactive shell and needs to access ...
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1answer
53 views

AWS public subnet autoscaling group with outbound NAT

I have seen this question : Static IP address for outgoing traffic from AWS autoscaling group but it doesnt seem to fit exactly what im trying to do. Here's the scenario: I have a autoscaling ...
2
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2answers
68 views

iptables drops packets after POSTROUTING

I have a malware analysis environment that will intercept traffic to arbitrary domains and Internet services using InetSim. I have a sandbox that has its DNS server set to the InetSim instance, and ...
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2answers
36 views

Trying to use source routing on two different interfaces

I have defined the following rules: -A POSTROUTING -j SNAT --to-source [publicip] -A POSTROUTING -j SNAT -d 192.168.0.0/24 --to-source 192.168.0.6 Basically, I want only the private network to go ...
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Securing remote access to local server behind NAT router [migrated]

I want to remotely access a Linux server in my private local LAN via HTTPS and SSH. The server ist connected to my DSL router (German Fritz!Box). As I can't directly access my server because of ...
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16 views

slow internet access when routing via a server (both using iptables NAT and ssh tunnelling) [migrated]

I have a spare computer powered by a dual core intel atom N550 CPU and 2GB RAM (I will refer this as "the server"). It is running lubuntu 14.10 x86 (32 bit) with lightdm service disabled (hence, no ...
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5answers
237 views

Router limits network performance but its CPU load isn't 100%

I'm using a PC Engines APU device running FreeBSD as a NAT router. The setup is very usual: one WAN connection and one LAN connection. Theoretically, WAN connection is 800/40 Mbit/s and the LAN one ...
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3answers
52 views

Cisco ASA NAT - internal host see its public ip

I have a server hosted by a provider which uses Cisco ASA to do nat. The problem I have is that the internal server that is nat-ed with a public ip will see its public ip as source ip. This basically ...
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45 views

Chaining two containers with docker

I have two containers that I have chained them together, so traffic that comes to container 2, first passes by container 1. I set container 2 --net=none. Host --- Container 1 --- Container 2 this is ...
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2answers
59 views

NAT a single IP using 2nd WAN Internet

I have a mikrotik RB750 (6.22) acting as a gateway for my LAN. Here is the basic configuration: Ether1-WAN1 (1.1.1.10/24) IPs are hidden for privacy Ether2-WAN2 (2.2.2.20/24) Ether5-LAN ...
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71 views

Why can't I SSH to this AWS NAT instance in a public subnet?

For experimentation purposes, I’m trying to setup an AWS EC2 inside a VPC that has both public and private subnets as described in this tutorial. However, when I try to SSH in step #2, it fails ...
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1answer
24 views

How to find how a port has been forwarded from main server to hypver v vm

I must appologise for being a novice in server administration but I have somehow been given the responsibility and I have spent a long time reading up on this. The issue I have is that the previous ...
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100 views

Use Openswan / IPSec on Ubuntu server to connect to existing Openswan VPN - NAT broken

I have an existing Openswan VPN, all working fairly well with Windows, Mac and Phones. [Office 192.168.0.0/24]---[VPN A.B.C.D]----[Internet]---[Home Routers (NAT), Dynamic IPs]----[Workstations] Now ...
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1answer
35 views

iptables port forwarding from public ip but not from 127.0.0.1

i have an issue with my network setting and i need a port forwarding a bit advanced. I need : - All packets that arrive on my public_ip on port 54321 to be forward on port 12345 but i don't want any ...
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1answer
57 views

Asterisk behind NAT sets wrong Contact Header

I'm using SIP with asterisk 13.1.0 behind a statically configured NAT. The servers private_ip differs from the public_ip, where I can reach it. I've already set these options in the sip.conf file. ...
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2answers
35 views

Port forward for SSH works to one system but not another

I have two systems sitting on a NATed network. When I forward port 22 to system A, I am able to connect directly. When I forward port 22 to system B, I am not able to connect. I am, however, able to ...
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1answer
31 views

IP forwading amazon ec2 another server IP

I use this command in windows azure (NAT), to redirect all requests to another server with other IP iptables -t nat -A PREROUTING -i eth0 -d 10.240.154.15 -j DNAT --to-destination 192.188.47.63 ¿ ...
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1answer
85 views

How to forward ports to DMZ using iptables and separate modem

I have a network that looks like this: ADSL VLAN 2 VLAN 3 ------[Modem]----------[firewall]----------[intranet PC] | | ...
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1answer
63 views

Linux firewall, ADSL bonding, two default routes

I am trying to set up a Linux firewall (ubuntu 14.04) to use two bonded ADSL lines for load balancing purposes. I found by searching the forum link to this: ...
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1answer
27 views

Is there any solution to change the source IP from outgoing WAN A to receiving WAN B?

I am configuring a office router for crossing the GFW in China. I want to use WAN A(actually a low bandwidth VPN tunnel) only to send package to target servers (YouTube for example). And change the ...
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1answer
57 views

How to make connections answer from the same gateway they entered in RouterOS?

I have a MikroTik RouterOS 6.23 device, and my network is as follows: Router | |-- bridge1_LAN (wlan1 + ether1) (192.168.0.210) -- LAN (192.168.0.0/24) | Here is where computers are. Those ...
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2answers
62 views

iptables: static ephemeral port maps

I have a VPN on my Linux server which does IPv4 NAT, example: iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT iptables -t nat -A ...
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1answer
206 views

NAT doesnt work on CentOS 7(Firewalld)

I have configured nat to make my CentOS 7 into a router. I have used firewalld to do this. But unfortunately it doesnt work. I have no idea which causes the issue. I tried the same configuration in ...
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1answer
78 views

Possible for Socket communication between 2 internet-connected GSM modems?

I have 2 internet-connected 4G modems connected to 2 separate computers and I'd like to send/receive data between them with sockets (UDP) using the modems' packet-switched 4G Internet connection, not ...
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1answer
108 views

NAT Rule changes from ASA software 8.0 to 8.4

I have an Access Rule and a NAT rule that works fine with on the Security Appliance Software Version 8.0 The rule is as follows: However, I am having trouble making the same rule work on an ASA ...
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112 views

Set up pfSense on AWS VPC?

I am attempting to setup pfSense as a nat box for internal servers on a VPC. I have followed the guides posted for configuring access and have followed the AWS instructions for setting up and ...
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0answers
28 views

Reverse proxy server that accepts connections from HTTP server - does it exist?

I'm the developer of an embedded hardware device which contains a lightweight HTTPS server. The problem is that I wish for the embedded device's web server to be accessed from outside when placed ...
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2answers
299 views

NAT to two different servers on the same port via hostname with Mikrotik RB2011

I have a Mikrotik RB2011 router, running RouterOS which connects to the internet via a static IP. In my lan I have two different servers, one that is on IP 192.168.89.11 and another on 192.168.89.12 ...
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0answers
45 views

Microtik router intervlan routing with NAT

I have setup as below: MTik Router RB450G(ether1) --> (fa0/1) Cisco Switch (fa0/2) --> Maipu Router, Internet Router MTik Router(ether2) --> My PC In fa0/1 , there are two VLANS trunked: ...
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39 views

Inbound redirects using ProxMox to NAT VM not working

I have configured ProxMox on a Hetzner Root Server. Its configured using their image under "Virtualisation". Once it was installed I could create a VM and its configured using NAT. This server gets an ...
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0answers
95 views

Amazon VPC NAT performance problems

I have a set of servers inside an Amazon VPC, whose job is to get image files from S3 and process them. The S3 downloads would frequently stall, sometimes for over 2 minutes, but all would eventually ...
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0answers
87 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 ...