LinuxQuestions.org
Download your favorite Linux distribution at LQ ISO.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Networking
User Name
Password
Linux - Networking This forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.

Notices

Reply
 
Search this Thread
Old 03-02-2005, 04:01 PM   #1
Jon Doe
LQ Newbie
 
Registered: Jul 2004
Posts: 16

Rep: Reputation: 0
Angry Multiple Gateways


Here is my situation:
I'm using SuSE 9.1 Pro.

I have two DSL connections both managed with Linksys routers.
Linksys #1- 192.168.1.1
Linksys #2- 192.168.1.50

I have the Linux box with two network cards setup as a gateway for the internal LAN.
eth0 - 192.168.0.1
eth1 - 192.168.1.253

The default route right now on the Linux box is 192.168.1.1 (Linksys#1)

I have successfuly setup NATing on the Linux box.
Right now my internal LAN points to 192.168.0.1 for a gateway and has internet access on Linksys #1.
I can simply switch my default gateway on the Linux box to 192.168.1.50 and then everyone has access on the second DSL connection (Linksys#2)

What I need to do is...
Get everyone accessing the net on the first DSL connection execpt for three clients.
I want three hosts on the internal LAN
192.168.1.51
192.168.1.52
192.168.1.53
to use the same gateway as everyone else (192.168.0.1) but get routed to use the second DSL connection.(192.168.1.50)

I have fooled around with NATing rules and route commands without success.
I am wondering if this "conditional routing" is possilbe with my current setup?
I have been able to setup multiple gateways depending on the traffic destination using route add -net etc... but that does not fully help me in my situation.

I hope this is clear. If I have missed sharing any needed information, please let me know and I will be happy to share more information.

Thanks so much for any light shed on my problem.
Sam

Last edited by Jon Doe; 03-02-2005 at 04:02 PM.
 
Old 03-03-2005, 06:27 PM   #2
zymurgist
Member
 
Registered: Jan 2003
Location: Long Island
Distribution: Redhat 8.0
Posts: 109

Rep: Reputation: 15
You didn't show your masks. I would really seperate the subnets if I were you. It would make routing much easier.

ken
 
Old 03-03-2005, 06:48 PM   #3
iamnotherbert
Member
 
Registered: May 2001
Posts: 74

Rep: Reputation: 15
I would think you need to use Iptables. Try using the -s command in your masquerade statement. I haven't tried this but it may work.. If you are interested in this solution I can help more.

I did the same thing for a client once but I used two linux boxes because of proximity. I set static routes with a batch file on the pc's to use one firewall for specific destinations and the other for other surfing.


m
 
Old 03-03-2005, 07:09 PM   #4
Jon Doe
LQ Newbie
 
Registered: Jul 2004
Posts: 16

Original Poster
Rep: Reputation: 0
Thanks for answering guys.
Couple of things:

If I subnet I am worried that the internal LAN wont be able to communicate with each other, including printers and NetBIOS etc...
Right now everything is on 255.255.255.0.

As far as the iptables are concerned, that is what I am using now, but I am using firewallbuilder to build my rules.
I tried NATing those three IP addresses to a specific NIC (eth2) then making the gateway for that NIC 192.168.1.50.
Is there a way with iptables, that I can forward certain hosts directly to another gateway?

Thanks again for your thoughts, I really appreciate them.
Sam

Last edited by Jon Doe; 03-03-2005 at 07:10 PM.
 
Old 03-03-2005, 07:58 PM   #5
iamnotherbert
Member
 
Registered: May 2001
Posts: 74

Rep: Reputation: 15
yeah i think you can masq to different gateways with iptables. Try to find where the firewall builder is putting the statement that says all traffic from the internal host masq out through the external interface. Manually edit that file and add the "iptables ... -s x.x.x.x ..." command. The -s specifies the source address. At least read up on the -s command for iptables and see if it can do what you want.


m
 
Old 03-04-2005, 12:36 AM   #6
Jon Doe
LQ Newbie
 
Registered: Jul 2004
Posts: 16

Original Poster
Rep: Reputation: 0
Alright, I will check to see what this -s switch is all about.
Thanks,
 
Old 03-04-2005, 10:48 AM   #7
guest
Member
 
Registered: May 2003
Distribution: CentOS 5 64 bit
Posts: 255

Rep: Reputation: 30
The tutorial of Multihomed Linux Networking is exactly what you are looking for!
 
Old 03-04-2005, 01:43 PM   #8
Jon Doe
LQ Newbie
 
Registered: Jul 2004
Posts: 16

Original Poster
Rep: Reputation: 0
This article is brilliant.
I have looked over it a couple time and I am almost getting it now...
Using this artile and learning how it works, will I be able to specify which internal clients get which gateway?
I think that I would be able to manipulate the commands from the article to do this. Do you know if I am correct in assuming that?
 
Old 03-07-2005, 01:07 PM   #9
zymurgist
Member
 
Registered: Jan 2003
Location: Long Island
Distribution: Redhat 8.0
Posts: 109

Rep: Reputation: 15
Your best bet to specify which clients get which gateway is to set up a DHCP server on your server and assign gateways to hosts. You could even group them together.
eg. (dhcpd.conf)
Code:
group {
  option routers    192.168.1.1;
  host client1 {
    hardware ethernet XX:XX:XX:XX:XX:XX;
    fixed-address 192.168.1.100;
  }
  host client2 {
    ...
  }
}
group {
  option routers    192.168.0.1;
  ...
}
ken
 
Old 03-07-2005, 03:26 PM   #10
pave
Member
 
Registered: Oct 2004
Posts: 42

Rep: Reputation: 15
I have multiple gateways done according to the tutorial that is posted in this thread. From my experience i have to say you that it doesnt work well in certain circumstances. It all depends what kind of services you use.

For example if you log into a DC++ hub (P2P) you will be kicked often. Why? Because hub will indicate that different IP is used for connection to hub and connection to other users.

Also it doesnt work well for gaming. Different gateways will give your connection diffrent latency=ping=lag what results in strage effects and disconnections.

On the other hand it works great with WWW

Go and hack it, if you manage to solve problems let me know. But for real multiple gateways i'm afraid BGP router should be used --> see "zebra"
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
multiple gateways efm Linux - Newbie 4 06-10-2005 08:50 AM
Multiple Gateways inforlinx Linux - Networking 1 02-22-2005 08:28 PM
Red Hat 7.3 and multiple gateways on multiple interfaces bluefmc Linux - Networking 2 11-19-2004 05:01 PM
multiple gateways john8675309 Linux - Software 0 05-24-2004 06:27 PM
multiple ips, multiple gateways, one interface drpixel Linux - Networking 6 12-04-2002 12:56 AM


All times are GMT -5. The time now is 06:20 AM.

Main Menu
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration