Linux - NetworkingThis forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Introduction to Linux - A Hands on Guide
This guide was created as an overview of the Linux Operating System, geared toward new users as an exploration tour and getting started guide, with exercises at the end of each chapter.
For more advanced trainees it can be a desktop reference, and a collection of the base knowledge needed to proceed with system and network administration. This book contains many real life examples derived from the author's experience as a Linux system and network administrator, trainer and consultant. They hope these examples will help you to get a better understanding of the Linux system and that you feel encouraged to try out things on your own.
Click Here to receive this Complete Guide absolutely free.
I have a strange nat problem
I became the administrator of a linux gateway using firehol.
This machine is a gateway for a small subnet /28. I have some DNAT enabled for some users to connect from home to their PC-s at work. Theese users connect to one of the IP's from my subnet. If I issue an iptables -t nat -L -n I can see the rules witch DNAT the traffic from theese users with destination to the local ip-s, but at the SNAT part I see the traffic going outside only SNAT-ed to my gateways IP.
So for example: Let's say I have 22.214.171.124 for my gateway, and 126.96.36.199 a pc behind that gateway. Users from home connect to 188.8.131.52 but theese are beeing DNAT-ed at the gateway to 192.168.X.X (a pc on the network). The problem is that according to iptables everything is SNAT-ed to 184.108.40.206 (the gateways ip).
But this is not true. If I start capturing packets with tcpdump I see that traffic sourced from 220.127.116.11. And the users can connect to their pc's (they connect to 18.104.22.168 and they get replies also from 22.214.171.124).
On the inside interface of the gateway I capture packets sourced from 192.168.x.x and on the outside interface they are sourced from 126.96.36.199. So the nat is done by the gateway.
I checked iptables -t nat and iptables -t mangle but this address 188.8.131.52 doesn't appear there.
Any help would be appreciated. Where else should I check? Firehol is doing something without iptables?