In computer networking, Network Address Translation (NAT) is the process of modifying IP address information in IPv4 headers while in transit across a traffic routing device.

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VirtualBox NAT Issue - Able to Ping and Lookup. Unable to Browse

I have been facing an unusual problem with my VirtualBox NAT settings. I have scoured the Unix SE Forums but was unable to find a similar issue reported. I did find one but it was from 2009 and ...
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267 views

Host a server with NGINX using VPN behind a NAT

so I was hosting a server using NGINX on a Raspberry Pi using a T-Mobile mobile router. All was working fine, till I noticed today that T-Mobile started to put me behind a NAT sometimes. So I heard ...
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29 views

IP NAT Routing with systemd-networkd and KVM

my setup looks like: KVM Hypervisor Ubuntu 15.10 with libvirt systemd-networkd configuration ==> 10-static.network <== [Match] Name=eth0 [Network] Bridge=br0 ==> 20-bridge.network <==...
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Redirect traffic to specific website

I am trying to setup something like a captive Portal but get stuck. I have an embedded device which starts a Wireless Access Point. Now I like to forward all traffic to a website on the device. I do ...
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240 views

Changing the port letsencrypt tries to connect on

So, one of my servers is behind NAT, and since there is already a publicly accessible apache server going on my LAN, I decided to access it from the outside with different ports, and remap them to the ...
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47 views

Connect to libreswan with ikev2 and behind nat

Server (Scientific Linux 7.2, like CentOS 7.2) with libreswan 3.15.7 in the internet cannot respond to a connection attempt if the client is behind NAT and insisting on using ikev2. It basically ...
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57 views

Applying NAT to traffic from GRE tunnel in OpenBSD PF

All I have a Cisco 877 router and a Linode VPS running OpenBSD 5.9 with a GRE tunnel running in between, which works great and I can ping from either side. I have set up a static route in the Cisco ...
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93 views

How to do iptables nat loopback?

I have a linux server behind the ISP's cablemodem-router combo. With some hacking I was able to make the port forwarding work, and the DHCP exceptions in the udhcpd. But I wasn't able to do the NAT ...
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How does iptables MASQUERADE work on the incoming side?

I'm still reading the iptables manual page and other documents and digging around questions and their answers. This is the problem which arises. When we setup the NAT we use a POSTROUTING rule such ...
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204 views

How does NAT reflection (NAT loopback) work?

I use the auto generated rules that come from OpenWRT as an example of NAT reflection (NAT loopback). So let's pretend there's a network 192.168.1.0/24 with two hosts (+ router): 192.168.1.100 and ...
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305 views

1:1 Stateless NAT kernel version 3.16 or later using TC

I am trying 1:1 stateless NAT traffic. The traffic is coming in via a GRE tunnel and exiting via a VPN. I have done enough research to understand that traffic entering a linux box off of the GRE ...
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59 views

iptables DNAT: 'No chain/target/match by that name'

I am trying to use DNAT on a new custom Linux target, but I get an error with the following basic command: #iptables -t nat -A PREROUTING -d 10.110.0.250 -p tcp --dport 9090 -j DNAT --to 10.110.0.239:...
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Networking, tl-wa5210g boadcast, dhcp. droping packets

Hi i have strange problem IPS is polish UPC and coaxial router This is technicolor with dhcp enabled Addres is 192.168.0.1 As my main gateway It is connected to the router as Ap in wpa2 wich one ...
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17 views

ALG IPSEC and RSTP

I have linux 3.18. my Linux is installet on a router. in this router I activate a NAT from the wan side. Does this Linux support ALG of IPSEC and RSTP ?
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73 views

Dose iptables NAT overwrite user agent of HTTP headers?

If i use iptables to NAT all HTTP traffic behind another network, does it overwrite user agent of HTTP headers? The rules are as follows: /usr/sbin/iptables -t nat -A POSTROUTING -o eth0 -j ...
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43 views

Answer redirect IP to specific port

I want make a system that has a few subdomains. I set each subdomain to IP address using DNS. I used random IP addresses for the question 165.93.198.34 x.mydomain.com (Which is actually 165.93.198....
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90 views

lxc container <-> external internet, what I missed?

I have Ethernet on my machine (enp0s10) that connected to real network, and I have lxcbr0 Ethernet bridge which gather lxc containers. And I want to make available one of lxc containers. So I wrote: ...
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64 views

NAT for second interface on private network

I have the following configured for my two network interfaces. eth1 10.93.90.1 (Production Network) eth0 192.160.0.1 (Private Network/Labb Network) I want to configure eth0 with NAT so I can ...
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116 views

IP forwarding through ssh tunnel

The situation involves 3 machines: A. Some laptop connected somewhere to the internet via any mean B. A server connected to the internet through a standard ISP (static IP provided by dyndns: ...
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51 views

scp to a KVM guest behind NAT

I have a KVM guest running on a server accessing it via virt-manager. I'm running the guest from my_pc. server has a public IP address and both my_pc and guest can ssh it. guest has a 168.192.x.x IP ...
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59 views

iptables Dynamic SNAT, how to force to use different src ip from pool?

Requirement: I need to translate a private-ip range to a public-ip range while going out on the internet. It should be a one-one mapping, if public-ip range exhausts it should drop to the next nat ...
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53 views

Configuring iptables for incoming static NAT

I got a router with ssh access to it, iptables are there waiting for me. I am trying to map any connection to port 1337 on both WAN/LAN to my computer's port 1337. How do I do that?
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7k views

How to redirect to my squid proxy using iptables since DNAT target: only valid in nat table

I want to redirect the traffic in my lan network through squid proxy but I am having some problems with iptables rules. When I use the following rule: # iptables -I FORWARD -s 192.168.1.0/255.255....
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Why doesn't iptables show my rule? [duplicate]

I ran the following command to configured NAT: iptables -t nat -A OUTPUT -p all -d 57.5.179.19 -j DNAT --to-destination 127.0.0.1 The rule seems to be working as when I make a request to that IP it ...
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151 views

Does “ip_forward” need to be enabled for any iptables SNAT/DNAT (postrouting/prerouting) rules?

I remember I had to enable ip_forward kernel parameter in the past in order to run SNAT/DNAT rules in iptables successfully. Today I was reading this post: http://blogs.aws.amazon.com/security/post/...
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Linux as router with multiple internet providers

Linux as router: I have 3 Internet providers, each with its own modem. Provider1, which is gateway address 192.168.1.1 Connected to linux router eth1/192.168.1.2 Provider2, gateway address 192.168.2....
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Alter DST port on bridged traffic

I need to rewrite the UDP destination port on traffic which is only bridged/L2, but I could not match this traffic via iptables. This traffic isn't going through NAT chains (it could be matched in ...
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1answer
60 views

1:1 NAT through VM VPN

I've got a few client servers that I connect to with different VPN clients (e.g. Cisco, OpenVPN, etc). I'm trying to set up an Ubuntu 14 VM (with VPN client permanently connected) for each server to ...
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340 views

Virtualbox - how to give Internet access and internal network access to two VMs?

I made two Virtualbox virtual machines, CentOS 7 latest iso. I gave them each 2 network interfaces, one NAT and one "Internal network" in order to get them to talk to each other and have Internet ...
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How do I change NAT type for UDP to be more P2P-friendly?

On gateway I do iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE, and on device I have this: $ stun stun.counterpath.net STUN client version 0.96 Primary: Indepndent Mapping, Port Dependent ...
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76 views

Linux access point (airmon-ng/airmon-ng) not working

Background: I am trying to set up an access point on Linux. The ultimate aim is to run SSLStrip (for an exercise) so I need to be able to do something like this, to redirect port 80 traffic through ...
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206 views

KVM - nat or bridge. How I do that

I have Debian Jessie server, and I have install apache server. From apache hosted several sites from different ip address. My server have resources for KVM. My question is - How I can set my free IP ...
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44 views

Access 2 VM's with one IPv4

I have two Virtual Machines. The 1st VM is running Debian 8.2 and the 2nd one is running Ubuntu Server 14.04.2 LTS Also I have one Public IPv4 The IPv4 assigns in only one server at a time. I assume ...
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83 views

iptables DNAT+SNAT: unwanted multiplication of the same udp datagram (and malfunction)

trying to figure out my mistake in the following very simple scenario: |peerA|(Aip:Aport) <--> (Bdev:Bip:Bport)|NatNode|(Cdev:Cip:Cport) <--> (Dip:Dport)| peerD (peer A emits datagrams ...
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linux to linux IP MASQUERADING failed (can't ping ip server)

I'm new in linux, i'm trying to IP MASQ. So the diagram is like linux A is connected to HUB and Internet, and linux B is connected only to HUB. In linux A i have eth1 (10.10.10.5) and eth0 (192.168.1....
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96 views

“ssh -L <port>” only working from local machine

I mean if I've got something like this: ssh -L 9000:itc.ua:80 andy@localhost It will open port 9000 on my local machine and when I hit http://localhost:9000 in Firefox it will forward to itc.ua:80 ...
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31 views

Forward public network around current network

For the purposes of this discussion, I have a very current always-on linux machine with two nics: wifi0 eth0 A very crude diagram of my desired configuration looks like this: ...
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2k views

Routing internet on NAT server thru Squid proxy

I've configured a Squid proxy and a NAT instance and both are functioning fine. Now I want to configure a proxy server on the NAT instance so that the internet on NAT is routed through the Squid ...
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2answers
667 views

FTP Troubleshooting

I have a centos 6.5 installed on Virtual Box. I'm trying to configure a basic ftp server. Below are details of it. Installed vsftpd from DVD/Yum: Status -> Successful Disabled firewall for test ...
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1answer
1k views

GlusterFS how to failover (smartly) if a mounted Server is failed?

In GlusterFS, lets say i have 2 Nodes (Servers) on a Volume. Lets say the volume info is something like this: Volume Name: volume-www Brick1: gluster-server-01:/volume-www/brick Brick2: gluster-...
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Why doesn't NAT reserve ports from the machine's TCP and UDP port pool?

I made two experiments. This is the network for both of them: [private network] [public network] A -------------------- R ----------------- B 192.168.0.5 192.168.0.1|192.0.2.1 ...
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1answer
229 views

ssh connection refused from same PC when going outside local network

I have sshd running on port 8000 running on a freshly installed plain vanilla Linux Mint 17.2 Rafaela. $ sudo netstat -tnlp | grep :8000 tcp 0 0 0.0.0.0:8000 0.0.0.0:* ...
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287 views

Rewrite source IP in TCP replies using iptables

I'd like to rewrite the source IP on TCP/514 traffic leaving a redhat machine, for connections that weren't initiated from the machine. The machine receives TCP/514 traffic on an interface, for ...
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AWS VPC NAT | ssh_exchange_identification: read: Connection reset by peer [closed]

I had a tough misleading error while connecting in AWS VPC subnets. The error did occur in B->A connection, and did not happen while A->B, so at the beginning I thought that it is library bug. It ...
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287 views

How check a port forwarded from localhost to localhost on.. localhost?

I'm learning about iptables, firewalling, routing and so on. I'm on Linux, Centos7, and I've set up a local port forwarding to localhost with: firewall-cmd --add-forward-port=port=2023:proto=tcp:...
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695 views

NAT box with multiple internal and external interfaces

Similar questions have been asked before but my setup is a little different and the solutions to those questions are not working. A have a CentOS 6 server running iptables with 5 interfaces: eth0: ...
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601 views

How to configure QoS per IP basis?

We have say 4 users in a private network connected to the Internet trough a Linux router with a public IP address that is doing network address translation (NAT). I gotta configure QoS to give access ...
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1answer
633 views

iptables Port Forwarding — no service with the port

I have setup a network as in the image below: Firewall (FW) running CentOS 6 has two physical interfaces with subinterfaces: eth0:2 — 10.100.1.78/25 eth0:3 — 10.100.1.79/25 eth3 — 192.168.0.21/24 ...
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810 views

strongSwan routing issue with roadwarrior behind NAT

Using the following ipsec.conf configuration: conn %default ikelifetime=60m keylife=20m keyingtries=3 rekeymargin=3m keyexchange=ikev2 esp=aes-aes256-...
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213 views

SSH Public key fails when using Reverse SSH Shell

I have a machine behind a NAT, which I would like to access via ssh. Lets call this machine A. I have machine B, which is publicly reachable, which I would like to route my ssh connections. I have ...