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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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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SSH E-mail login alert if SSH port is as NAT

Can you help me with this problem please? How can I set e-mail alerting after SSH login when port 22 is NATed? I use Linux Debian 7. I have used these iptables rules: eth0 - external network, eth1 - ...
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56 views

Why aren't my iptables rules appearing in the relevant list after reboot?

I am trying to write two persistent NAT rules, which I save via iptables-save > /etc/iptables.ipv4.nat, and restore upon reboot via pre-up iptables-restore < /etc/iptables.ipv4.nat in my ...
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IPtables rule to double NAT [closed]

Let me rephrase it.. I just need an IPtable rule to do double NAT-ting.. Host A - Host B - Host C - Host D Host B should do both source NAT and destination NAT, so that my request from Host A ...
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110 views

iptables: redirect local request with NAT

I'd like to redirect local requests to port which is translated with NAT. I have following rules: iptables -t nat -A PREROUTING -p tcp --dport 9020 -j DNAT --to 10.0.3.11:80 however request coming ...
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Routing Application through different network interfaces [duplicate]

I have two interfaces on a server, let's call them eth0 and eth1. The underlying server is running CentOS 6.5 I would like to be able for some application to use eht0 while some others use eth1. ...
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94 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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Redirection to services in NAT or Bridged Network only with one subdomain

I have one subdomain (dyndns). xyz.dyndns.com (f.e.) Here my question begins: I have a server for virtualisation. On the server I have multiple VMs where different web-services are available ...
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Portforwarding: router nat vs iptables [closed]

I would like to host some services on my pc and make them available from internet. (I'm aware of the security implications, it's more like a test for now). I don't have experience with iptables but I ...
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53 views

SNAT / Masquerade with shorewall

I've got a little question about Masquerading and SNAT in combination with shorwall and KVM. The Operating System is Scientific Linux 6.4. Setup is like this at my root server: Virtual Machine IP ...
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49 views

How to forward one port to another (on the same machine)?

A machine (M) is behind a NAT. Port X is forwarded through, and available to the internet. My application wants to connect to port Y. How to I configure M to forward incoming data on port X to port ...
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iptables: The “script” way or the “*filter, rules, COMMIT” way?

I'm trying to figure out how NAT and iptables work. While I'm in the trial-and-error phase of learning about it, I found two somewhat conflicting howtos. One howto uses a script to call iptables ...
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1answer
169 views

How to open VPN connection inside other VPN connection under Linux/Ubuntu

Is it possible to have two VPN connections on top of each other under Ubuntu? Scenario: My organization is quite large and has its own large network. Each group inside the organization has its own ...
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31 views

pf out interface?

I'm trying to figure out how to allow all hosts in $dmz to reach any host when egressing $extif. I can't seem to find the equivalence of netfilters "-o $extif", and I'd like to avoid specifically ...
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1answer
111 views

Managing iptables for home lan routing

I have a LAN at home. One Netgear router - 192.168.0.1 connected to the internet. One Macbook - 192.168.0.10 (connected to Netgear router) One PC with Kali Linux - 192.168.0.20 (connected to ...
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574 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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85 views

FreeBSD pf firewall, new connections severly delayed when nating

I have a newly setup fbsd 9.1 with pf, which itself doesn't experience any slowness when for example downloading a debian iso from my local debian repo (ftp.se.debian.org). Any machine behind it, ...
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157 views

NetworkManager connection sharing doesn't seem to NAT packets

After setting up network sharing the easy way on the Ubuntu machine, and getting an IP address via DHCP on the Arch Linux machine downstream, the Arch machine is able to ssh to the Ubuntu machine and ...
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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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2answers
170 views

PF and types of NAT(Network Address Translation)

As you know, at least 3 types of NAT are used. Of course i need to two types of them.DNAT and SNAT. DNAT : hiding server behind NAT, SNAT : hiding your client behind NAT. Question: I read a quick ...
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795 views

iptables: how to allow traffic from redirected port

I have a web service running on debian 7 and listening on port 8080. I want to redirect 80 to 8080 for inbound connections and allow only port 80. Here is my iptables configuration: root@localhost:~# ...
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388 views

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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In Linux is there any tools or package which can do STUN TURN ICE NATs and firewalls break end-to-end connectivity

In Linux is there any way to do this NATs and firewalls break end-to-end connectivity with existing package or tools? e.g: close source cant use it for free ...
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1answer
233 views

Can iptables be used to convert a single-homed host into a NAT server?

Given: I have a machine (HostA) with only one NIC which has Internet connectivity. I have another machine (HostB) with one NIC on the same switch. HostB is not configured for Internet access yet. ...
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689 views

Sniffing VirtualBox machine behind NAT

I have a VirtualBox machine with a single interface connected to VB's NAT mode. What I would like to do is sniff all traffic coming from/to any machine behind that NAT. (I don't think I will need to ...