From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dhirendra Pal Singh Date: Thu, 13 Mar 2003 01:36:32 +0000 Subject: Re: [LARTC] ABout Routing..again Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org Thanks a lot once again Martin. Yes this is the correct diagra. Mean while I have agian posted my question with the diagram fixed. Please ignore it. Got your point Martin about why its not working. I will try it later again. I apologise for posting the wrong question.. and thank once again to Martin for taking the pains to correct the diagram and sending and answer. I was in a fix and didnt knew where to send the question. I paniced.. sorry.. I will take care of this in future.. Thanks Dp Martin A. Brown wrote: >Dhirendra, > > : Dsl feed goes to gateway 1. Its internal ip address is of 192.168.1.XXX. > : Now from here goes the feed to another gateway which eth0 ip address is > : 192,168.1.50. It has 2 more eth - eth1 and eth2. Their ip address are > : 192.168.2.51 and 192.168.3.XXX respectively. > : Now my problem is that all the computers connect to 192.168.2.XXX are > : unable to point to the computers of 192.168.1.XXX. Though strangely I > : can ping to 192.168.1.1 wich is the internal ip address of the gateway 1. > >Is this your network, or did I mangle it in reconstruction? > > > eth0 > 192.168.1.50 > \ > |----------| |----------| > | gateway 1|-------------------------| gateway2 | > /|__________|\ | |----------| > / \ | / \ > eth0 eth1 | / \ > 61.X.X.X 192.168.1.1 | eth1 eth2 >(public) | 192.168.2.51 192.168.3.52 > | | > ------------ | > | BOX 1 | ------------- > ------------ | Box 3 | > 192.168.1.101 ------------- > 192.168.3.101 > > >You can ping 192.168.1.1 because it is a locally hosted IP on the default >gateway of the machines in the 192.168.2.0/24 network. > > : I have the following setup on redhat linux 8.0 ... > : > : A) I am unable to ping from Box 3 (192.168.3.101) to Box 1. Any > : comments or reasons why? > >It looks like you have a common routing problem. If you examine the >routing tables on gateway 1 and box 1, they are probably missing routes >to 192.168.3.0/24 and 192.168.2.0/24 via 192.168.1.50. Host 1 probably >has a default route to 192.168.1.1 and gateway 1 certainly doesn't have a >default route pointing *into* your network. > > >This is not really a LAR (and certainly not a TC) question. This is a >basic routing question. Let's try to keep these questions off the LARTC >list....this is probably better for a forum like comp.os.linux.networking >or a LUG. > > > >You may find some of my documentation useful in conceptualizing static >routing: > > http://linux-ip.net/ > http://linux-ip.net/html/ch-routing.html > >For others who are following along with questions like this, I would >recommend using a network analyzer of some kind to look at the packets on >each of the machines involved. > > - use tcpdump or ethereal on each affected router and end-host > - generate regular traffic (ping, nc, socat, etc.) while trying to > determine where the packets are getting dropped or misrouted > > >So, Dhirendra: > >Remove the masquerading from gateway2 > >[root@box1]# ip route add 192.168.3.0/24 via 192.168.1.50 >[root@box1]# ip route add 192.168.2.0/24 via 192.168.1.50 >[user@box3]$ ping -n 192.168.1.101 > >You should get a response. > >[root@box2]# ip route add 192.168.3.0/24 via 192.168.1.50 >[root@box2]# ip route add 192.168.2.0/24 via 192.168.1.50 > > : B) I have figured out that if I enable Masquerading then problem A is > : solved. Can someone explain why? > >Because you are changing the source IP on the packets to a 192.168.1.0/24. >When you do this, the other hosts in 192.168.1.0/24 have a direct route >for reply packets. > > : C) Is it possible without Masquerading ? > >Yes. > >-Martin > >Anybody think a LARTC FAQ is a good idea? > > > _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/