iptables NAT configuration

Posted by Sarp Kaya on Server Fault See other posts from Server Fault or by Sarp Kaya
Published on 2012-10-06T11:11:47Z Indexed on 2012/10/06 15:39 UTC
Read the original article Hit count: 300

Filed under:

iptables

|

nat

Hello I am experiencing some issues with my iptables. Here's what I want to do:

A(eth0)--------(eth0)B(eth2)---------------(eth2)C

Brackets are interface names A,B and C are hosts. Now I would like to forward port number 80 of host C so that It would be accessed via host A. host A is 192.168.1.254 host C is 192.168.3.2

I intentionally ACCEPTed all FILTER chain options as the default policy because I wanted to make sure that NAT is working properly first. I enabled ip_forward.

So here's what I have done:

sudo iptables -A PREROUTING -t nat -p tcp - d 192.168.1.254 -j DNAT --to 192.168.3.2

However it is not working. What am I missing here?

© Server Fault or respective owner

Related posts about iptables

Sometimes this script fails to update the iptables

as seen on Server Fault - Search for 'Server Fault'
It does not happen often, but sometimes after running the below script, checking the iptables with service iptables status shows that they weren't updated and the script doesn't output any error. The iptables is structured as look-up tree (long repeated sections snipped): #!/bin/sh iptables -t… >>> More
My current iptable configuration doesn't work [on hold]

as seen on Server Fault - Search for 'Server Fault'
sudo chkconfig iptables off /etc/init.d/iptables on ### Clear/flush iptables sudo iptables -F sudo iptables -P INPUT ACCEPT sudo iptables -P OUTPUT ACCEPT sudo iptables -P FORWARD ACCEPT ### Allow SSH iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT iptables… >>> More
L2TP iptables port forward

as seen on Server Fault - Search for 'Server Fault'
Hi all, I'm setting up port forwarding for an L2TP VPN connection to the local Windows 2003 VPN server. The router is a simpel Debian machine with iptables. The VPN server works perfect. But I cannot log in from the WAN. I'm missing something. The VPN server is using a pre-shared key (L2TP) and… >>> More
iptables -P FORWARD DROP makes port forwarding slow

as seen on Server Fault - Search for 'Server Fault'
I have three computers, linked like this: box1 (ubuntu) box2 router & gateway (debian) box3 (opensuse) [10.0.1.1] ---- [10.0.1.18,10.0.2.18,10.0.3.18] ---- [10.0.3.15] | box4, www [10.0.2.1] Among other… >>> More
IPtables AWS EC2 NAT/Reverse NAT - For Reverse Proxy style setup but with IPtables

as seen on Server Fault - Search for 'Server Fault'
I was thinking initially needing to do a reverse proxy or something so I could get some SSL/TLS traffic look like it is being terminated at a server and IP address in the AWS cloud, and then that traffic is forwarded onto our actual web servers that aren't in the cloud... I've not done much iptables… >>> More

Related posts about nat

Cisco 881 losing NAT NVI translation config after reload

as seen on Server Fault - Search for 'Server Fault'
This is a weird one, so I'll try to explain in as much detail as I can so I'm giving the whole picture. As I've mentioned in my other questions, I'm in the process of setting up a new Cisco 881 as my WAN router and NAT firewall. I'm facing an issue where NAT NVI rules that I have configured are not… >>> More
IPtables AWS EC2 NAT/Reverse NAT - For Reverse Proxy style setup but with IPtables

as seen on Server Fault - Search for 'Server Fault'
I was thinking initially needing to do a reverse proxy or something so I could get some SSL/TLS traffic look like it is being terminated at a server and IP address in the AWS cloud, and then that traffic is forwarded onto our actual web servers that aren't in the cloud... I've not done much iptables… >>> More
asterisk/freeswitch in nat/no-nat setup

as seen on Server Fault - Search for 'Server Fault'
hi, my current setup - i use bunch of sip hard-phones around few offices. all devices have two sip accounts configured - one on internal sip proxy [for calls between the branches], another - at 3rd party voip providers [ since it's in different countries - those are different providers, but that's… >>> More
Problem with setup VPN in Ubuntu Server 12.04

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I have a problem with setup VPN server on my Ubuntu VPS, here is my server environments: Ubuntu Server 12.04 x86_64 xl2tpd 1.3.1+dfsg-1 pppd 2.4.5-5ubuntu1 openswan 1:2.6.38-1~precise1 After install software and configuration: ipsec verify Checking your system to see if IPsec got installed and… >>> More
Problem with setup VPN on Ubuntu Server 12.04

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I have a problem with setup VPN server on my Ubuntu VPS, here is my server environments: Ubuntu Server 12.04 x86_64 xl2tpd 1.3.1+dfsg-1 pppd 2.4.5-5ubuntu1 openswan 1:2.6.38-1~precise1 After install software and configuration: ipsec verify Checking your system to see if IPsec got installed and… >>> More