connecting 3 PCs

[TotallyLost]

Hey everyone
I've three VMs, VM 1 and 2 has one network adapter and the third has 2 network adapters.
I've configered VM3 as follow
eth0
IPAdress 192.168.1.1
Subnet Mask 255.255.0.0
Defult Gateway 192.168.1.1

eth1
IPAdress 192.168.5.1
Subnet Mask 255.255.0.0
Defult Gateway 192.168.5.1

And I've enabled the forwarding in it…

For VM2, I configured its adabter as follow

IPAdress 192.168.1.10
Subnet Mask 255.255.0.0
Defult Gateway 192.168.1.1

and VM1 as follow

IPAdress 192.168.5.5
Subnet Mask 255.255.0.0
Defult Gateway 192.168.5.1

I made 2 LANs I put VM3 in the two LANs, and VM1 in LAN1 and VM2 in LAN2

Now I want to ping VM1 from VM2 or vice versa, and it simply tells me destination host unreachable, whats wrong with my setups?

[07CobaltGirl]

So you're using VM3 as a router between VM1 and VM2. Any particular reason for your subnet mask being 255.255.0.0? It makes both subnets overlap. Try changing it to 255.255.255.0 and see what happens.

[TotallyLost]

Thank you so much for your note
now I can ping both interfaces in VM3 from VM1 and VM2, but still can't ping VM1 from VM2 or vice versa, what may be wrong?

[stevea]

probably the best question to you is - what are you trying to accomplish.
There are easier ways to connect three VMs if that's the goal.


What are the route table s on VM3 ?
Use the command

ip route

Also examine the iptables icmp (ping) entries handling on Vm3. It's entirely possible that tcp and udp are working even when ping fails.

[TotallyLost]

what I really want is, to make VM1 act as a client, VM2 to act as a server and VM3 act as a transparent machine, so that if VM1 made a request to VM2, this request should pass through VM3 before going to VM2 to execute some code, so I'll put some iptable rules on VM3 to take the HTTP requests from port 80 and forward it to the port my code is listing to. so, as a beginning step, I just tried to connect the three VMs and try to ping, then I'll add the iptables rules later, that's it.
For the ip rout it gives me
192.168.5.0/24 dev eth0 proto kernal scope link src 192.168.5.1 metric 1
192.168.1.0/24 dev eth1 proto kernal scope link src 192.168.1.1 metric 1

[07CobaltGirl]

So VM1 can ping both interfaces on VM3, and VM2 can ping both interfaces on VM3, but VM1 cannot ping VM2 or vice versa? Or are you saying VM1 can ping its attached interface only on VM3 and same for VM2?

[TotallyLost]

no, the case is, VM1 can ping both interfaces on VM3, and VM2 can ping both interfaces on VM3, but VM1 cannot ping VM2...

[07CobaltGirl]

Tomorrow is my Friday, so I'll play with it tomorrow if this isn't resolved. The only thing I can think of right off the top of my head is you're VM3 interfaces don't know what they're connected to, or are misconfigured. Could be as simple as a mismatched subnet mask on one of the interfaces, or could be a firewall issue?

[TotallyLost]

Dear cobaltgirl, I can thank u enough
but its not a firewall issue i am sure...