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 difficulties opening a single specific port on my linux machine for my BitTorrent client. When probing this or any other port using grc.com I only get status 'stealth' (the infamous NAT-problem), although I adjusted iptables configuration and set port forwarding on both my modem and router. I am obviously overlooking something elementary here, but that's what being newbie is all about, isn't it? I've been searching the net and any forum possible, but nothing works well. So now I turn to you in utter despair...
My configuration looks like this:
ADSL modem --->--- Broadband Router --->--- 2 Linux machines and a Windows box
- My ADSL modem receives a dynamic IP from my ISP. I set port forwarding from 0.0.0.0:myport to privateIP:myport for both tcp and udp.
- My Broadband router with static IP is also forwarding the same port to the same address.
- I configured iptables on my Linux machine (RH9, fixed IP) according to the Azureus Wiki.
When running Azureus, netstat -pantu returns
tcp 0 0 privateIP:myport 0.0.0.0:* LISTEN 1581/java
so that's working fine.
Shutting down iptables didn't work, port probing keeps returning 'stealth'. Probing for port 80 too. Very confusing. I think it has something to do with my network setup, but I don't know what. Searching the internet only gives me headaches.
netstat -r returns the following:
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
x.x.0.0 * 255.255.255.0 U 0 0 0 eth0
169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default routerIP 0.0.0.0 UG 0 0 0 eth0
Everything is working perfectly fine, also Azureus (but only with the NAT-error). Can anyone help me? I know this problem has come up numerous times in numerous forums, but no description fits my problem.
Thanks in advance,
I tried nmap -sT and nmap -p 1-myport on both my router and on my ADSL modem, but myport doesn't show up.
Are you trying this against the router's internal interface? If so, that will not tell you what you want. You need to test against the external interface - as I said from somewhere out on the web.
If this is My Problem, then how can I open my router to the world?
Check the router manual. You need to explicitly tell it to open a port and forward requests to it to the correct machine on your private network. If you have done this correctly, a port scan from the outside world will show the port as open. That's step 1 anyway..
Yes! I did it! Port probing using grc.com gave 'open'. I had to change port forwarding in my ADSL modem from my machine's private IP to my router's WAN IP. Port forwarding in my router to my private IP was correct.
And tell you what, I actually got those green smileys in Azureus, indicating that it's working fine now!
Thank you so much for your help putting me on the right track.