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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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 ...
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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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10 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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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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30 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 ...
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1answer
22 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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52 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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87 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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31 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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33 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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36 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 ...
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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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1answer
79 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: ...
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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 ...
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116 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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29 views

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
48 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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1answer
150 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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29 views

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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188 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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65 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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1answer
124 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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43 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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61 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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56 views

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 ...
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57 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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27 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
521 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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973 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: ...
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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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190 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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233 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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223 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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2k views

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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1answer
189 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 ...
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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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1answer
447 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
617 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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106 views

Why is my laptop being blocked from connecting to a PPTP VPN server?

I have a fairly simple network at home Internet --> Modem --> Linux Router --> Switch --> Laptop The problem: There is a PPTP VPN server at work that I need to connect to from home. I configured my ...
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667 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 ...
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193 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 ...
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Randomize external port when doing NAT with iptables

I want to configure a NAT behavior different from the default one implemented by iptables. In this example: iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to-source 193.49.142.107:2000-400 The ...
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Send traffic to self over physical network on Ubuntu

I have a dual port ethernet NIC and let's say I have connected both ports in a loop and assigned the following IPs to the 2 ethernet interfaces: eth2 -> 192.168.2.1 eth3 -> 192.168.3.1 I want to ...
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Can not reach local DNS server for local dot domain subzones because firewall returns gateway IP

I have pfSense inline between my cable modem and my switch, on pfSense I have a NAT port forward on 53 to my local DNS server which I want to serve local subzones to the LAN with. Right now when I dig ...
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117 views

linux nat different rules

eth0 (192.168.1.0/24) --> wan eth2 (192.168.10.0/24) --> lan0 I use these rules to enable NAT on my linux gateway: iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE iptables -A FORWARD -i ...
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572 views

CentOS as home network router: IPTables Port Forwarding failure

I have currently set up a home server with a CentOS 6.6 installation on it. The server has two NIC interfaces which I'm using it as my router and DHCP server. Here's a diagram showing the network ...
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1answer
184 views

Does NAT allow accessing internal network (or router's local interface) from outisde by default?

I am using older SOHO router wl500gP (it is v1 but I think this is not important) with custom Oleg firmware. My topology looks like this: 192.168.3.3 192.168.3.2 NAT 192.168.2.1 ...
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Enable ssh host to guest & guest Internet on CentOS 7 guest with VirtualBox

I have 2 CentOS 7 guests running in VirtualBox on a Ubuntu host. I want to be able to: Connect using ssh from host to guest Download/install packages from the Internet on the guest. I currently ...